Ошибка при подтверждении новой строки foreign key mismatch referencing

Why am I getting a SQLite «foreign key mismatch» error when executing script below?

DELETE 
FROM rlsconfig 
WHERE importer_config_id=2 and 
program_mode_config_id=1

Here is main table definition:

 CREATE TABLE [RLSConfig] (
        "rlsconfig_id"      integer PRIMARY KEY AUTOINCREMENT NOT NULL,
        "importer_config_id"        integer NOT NULL,
        "program_mode_config_id"        integer NOT NULL,
        "l2_channel_config_id"      integer NOT NULL,
        "rls_fixed_width"       integer NOT NULL
    ,
        FOREIGN KEY ([importer_config_id])
            REFERENCES [ImporterConfig]([importer_config_id]),
        FOREIGN KEY ([program_mode_config_id])
            REFERENCES [ImporterConfig]([importer_config_id]),
        FOREIGN KEY ([importer_config_id])
            REFERENCES [ImporterConfig]([program_mode_config_id]),
        FOREIGN KEY ([program_mode_config_id])
            REFERENCES [ImporterConfig]([program_mode_config_id])
    )

and referenced table:

    CREATE TABLE [ImporterConfig] (
        "importer_config_id"        integer NOT NULL,
        "program_mode_config_id"        integer NOT NULL,
        "selected"      integer NOT NULL DEFAULT 0,
        "combined_config_id"        integer NOT NULL,
        "description"       varchar(50) NOT NULL COLLATE NOCASE,
        "date_created"      datetime NOT NULL DEFAULT (CURRENT_TIMESTAMP),
        PRIMARY KEY ([program_mode_config_id], [importer_config_id])
    ,
        FOREIGN KEY ([program_mode_config_id])
            REFERENCES [ProgramModeConfig]([program_mode_config_id])
    )

I’m trying to create an Associative Entity (N:N) in SQLite like this:

[ Pet —< VaccinePet >— Vaccine ]

And, I have the follow code of my associative entity:

CREATE TABLE  VACINAPET (
        vp_date TEXT NOT NULL,
        vp_is_applied INTEGER DEFAULT 0,
        fk_pet INTEGER,
        fk_vaccine INTEGER,
        FOREIGN KEY (fk_pet) REFERENCES pet (pet_id),
        FOREIGN KEY (fk_vaccine) REFERENCES vaccine (vaccine_id),
        PRIMARY KEY (fk_pet, fk_vaccine) 
);

BUT, I’m getting an error:

foreign key mismatch — «VACCINEPET» referencing «vaccine»: INSERT INTO
VACCINEPET (vp_date, vp_is_applied, fk_pet, fk_vaccine) VALUES
(’23/05/2018′, 0, 1, 1);

When I try to use the INSERT command:

INSERT INTO VACINAPET (vp_data, vp_is_aplicada, fk_pet, fk_vacina)
VALUES (’23/05/2018′, 0, 1, 1);

What could be wrong? I’m not so good in database…

MASTER DETAIL: I have data in Pet table and Vaccine table, they are not empty

Having worked with databases for over 30 years, and after looking over your database definitions, I see several issues with your database that should be corrected, restructured, or optimized.  I am not going to go into all of those issues since this is primarily an AutoIt forum not a SQL and/or database forum.  However, I will try to answer your specific question as to why you are getting this particular foreign key error, how you can begin to trouble shoot such issues in SQLite in the future, and one way that you can resolve this particular error.

First, to identify glaring foreign key issues, you can execute the following SQLite pragma command on the database.  When you execute the command on the DB that you attached, you will see the following error.  The pragma command will not find all foreign key errors, just the ones that the processor can detect at the time.

pragma foreign_key_check;

Result: foreign key mismatch - "postinstall_user" referencing "postinstall"

Why are you getting that error?  The following excerpt from the SQLite documentation will shed some light on the issue:

Usually, the parent key of a foreign key constraint is the primary key of the parent table. If they are not the primary key, then the parent key columns must be collectively subject to a UNIQUE constraint or have a UNIQUE index. If the parent key columns have a UNIQUE index, then that index must use the collation sequences that are specified in the CREATE TABLE statement for the parent table.
.
.
.
 If the database schema contains foreign key errors that require looking at more than one table definition to identify, then those errors are not detected when the tables are created. Instead, such errors prevent the application from preparing SQL statements that modify the content of the child or parent tables in ways that use the foreign keys. Errors reported when content is changed are "DML errors" and errors reported when the schema is changed are "DDL errors". So, in other words, misconfigured foreign key constraints that require looking at both the child and parent are DML errors. The English language error message for foreign key DML errors is usually "foreign key mismatch" but can also be "no such table" if the parent table does not exist. Foreign key DML errors are reported if:

   * The parent table does not exist, or
   * The parent key columns named in the foreign key constraint do not exist, or
   
   * The parent key columns named in the foreign key constraint are not the primary 
     key of the parent table and are not subject to a unique constraint using collating 
     sequence specified in the CREATE TABLE, or
     
   * The child table references the primary key of the parent without specifying the 
     primary key columns and the number of primary key columns in the parent do not 
     match the number of child key columns.

In this particular case, the third bullet, above, is the reason why you are having an issue.  If you refer back to the result of the pragma command, it say that there is a foreign key defined in the postinstall_user table that references the postinstall table, that has a problem.  Your postinstall_user table is defined as:

CREATE TABLE [postinstall_user] (
    [installer_id] INTEGER NOT NULL REFERENCES [installer]([id]) ON DELETE CASCADE ON UPDATE CASCADE DEFERRABLE INITIALLY DEFERRED,
    [sequence_id] INTEGER NOT NULL REFERENCES [postinstall]([sequence_id]) ON DELETE CASCADE ON UPDATE CASCADE DEFERRABLE INITIALLY DEFERRED,
    [user_id] INTEGER NOT NULL REFERENCES [user]([id]) ON DELETE CASCADE ON UPDATE CASCADE DEFERRABLE INITIALLY DEFERRED,
    PRIMARY KEY (
        [installer_id],
        [sequence_id],
        [user_id]
        )
    )

As you can see, there is one foreign key in that table that references the postinstall table.  sequence_id is not the complete primary key in the postinstall table.  The primary key in that table is defined as «PRIMARY KEY([installer_id], [sequence_id]))».  Therefore to satisfy the third bullet of the documentation, if you change the definition of that foreign key to match the primary key in the postinstall table, it should fix your issue.  So the definition of that postinstall_user table should look something like:

CREATE TABLE postinstall_user (
    installer_id INTEGER NOT NULL,
    sequence_id  INTEGER NOT NULL,
    user_id      INTEGER NOT NULL,
    PRIMARY KEY (installer_id, sequence_id, user_id),
    FOREIGN KEY (installer_id, sequence_id) REFERENCES postinstall (installer_id, sequence_id) 
        ON DELETE CASCADE ON UPDATE CASCADE DEFERRABLE INITIALLY DEFERRED,
    FOREIGN KEY (user_id) REFERENCES user (id) 
        ON DELETE CASCADE ON UPDATE CASCADE DEFERRABLE INITIALLY DEFERRED
);

After making that change, when I delete the installer record or a user record, the related records, as you defined them, are successfully deleted.

I hope that helps.

Installer — New.db

Edited December 30, 2020 by TheXman

Attached modified DB

SQLite Foreign Key Support

Overview

This document describes the support for SQL foreign key constraints
introduced in SQLite version 3.6.19 (2009-10-14).

The first section introduces the
concept of an SQL foreign key by example and defines the terminology
used for the remainder of the document. Section 2 describes the steps
an application must take in order to enable foreign key constraints in
SQLite (it is disabled by default). The next section, section 3,
describes the indexes that the user must create in order to use
foreign key constraints, and those that should be created in order for
foreign key constraints to function efficiently. Section 4 describes
the advanced foreign key related features supported by SQLite and
section 5 describes the way the ALTER and DROP TABLE commands are
enhanced to support foreign key constraints. Finally, section 6
enumerates the missing features and limits of the current implementation.

This document does not contain a full description of the syntax used
to create foreign key constraints in SQLite. This may be found as
part of the documentation for the CREATE TABLE statement.

1. Introduction to Foreign Key Constraints

SQL foreign key constraints are used to enforce «exists» relationships
between tables. For example, consider a database schema created using
the following SQL commands:

CREATE TABLE artist(
  artistid    INTEGER PRIMARY KEY, 
  artistname  TEXT
);
CREATE TABLE track(
  trackid     INTEGER,
  trackname   TEXT, 
  trackartist INTEGER     -- Must map to an artist.artistid!
);

The applications using this database are entitled to assume that for
each row in the track table there exists a corresponding row in the
artist table. After all, the comment in the declaration says so.
Unfortunately, if a user edits the database using an external tool or
if there is a bug in an application, rows might be inserted into the
track table that do not correspond to any row in the artist
table. Or rows might be deleted from the artist table, leaving
orphaned rows in the track table that do not correspond to any of
the remaining rows in artist. This might cause the application
or applications to malfunction later on, or at least make coding the
application more difficult.

One solution is to add an SQL foreign key constraint to the database
schema to enforce the relationship between the artist and
track table. To do so, a foreign key definition may be added
by modifying the declaration of the track table to the following:

CREATE TABLE track(
  trackid     INTEGER, 
  trackname   TEXT, 
  trackartist INTEGER,
  FOREIGN KEY(trackartist) REFERENCES artist(artistid)
);

This way, the constraint is enforced by SQLite. Attempting to insert
a row into the track table that does not correspond to any
row in the artist table will fail, as will attempting to
delete a row from the artist table when there exist dependent
rows in the track table There is one exception: if the foreign
key column in the track table is NULL, then no corresponding
entry in the artist table is required. Expressed in SQL, this
means that for every row in the track table, the following
expression evaluates to true:

trackartist IS NULL OR EXISTS(SELECT 1 FROM artist WHERE artistid=trackartist)

Tip: If the application requires a stricter relationship between
artist and track, where NULL values are not permitted
in the trackartist column, simply add the appropriate
«NOT NULL» constraint to the schema.

There are several other ways to add an equivalent foreign key declaration
to a CREATE TABLE statement. Refer to the
CREATE TABLE documentation for details.

The following SQLite command-line session illustrates the effect of the
foreign key constraint added to the track table:

sqlite> SELECT * FROM artist;
artistid  artistname       
--------  -----------------
1         Dean Martin      
2         Frank Sinatra    

sqlite> SELECT * FROM track;
trackid  trackname          trackartist
-------  -----------------  -----------
11       That's Amore       1  
12       Christmas Blues    1  
13       My Way             2  

sqlite> -- This fails because the value inserted into the trackartist column (3)
sqlite> -- does not correspond to row in the artist table.
sqlite> INSERT INTO track VALUES(14, 'Mr. Bojangles', 3);
SQL error: foreign key constraint failed

sqlite> -- This succeeds because a NULL is inserted into trackartist. A
sqlite> -- corresponding row in the artist table is not required in this case.
sqlite> INSERT INTO track VALUES(14, 'Mr. Bojangles', NULL);

sqlite> -- Trying to modify the trackartist field of the record after it has 
sqlite> -- been inserted does not work either, since the new value of trackartist (3)
sqlite> -- Still does not correspond to any row in the artist table.
sqlite> UPDATE track SET trackartist = 3 WHERE trackname = 'Mr. Bojangles';
SQL error: foreign key constraint failed

sqlite> -- Insert the required row into the artist table. It is then possible to
sqlite> -- update the inserted row to set trackartist to 3 (since a corresponding
sqlite> -- row in the artist table now exists).
sqlite> INSERT INTO artist VALUES(3, 'Sammy Davis Jr.');
sqlite> UPDATE track SET trackartist = 3 WHERE trackname = 'Mr. Bojangles';

sqlite> -- Now that "Sammy Davis Jr." (artistid = 3) has been added to the database,
sqlite> -- it is possible to INSERT new tracks using this artist without violating
sqlite> -- the foreign key constraint:
sqlite> INSERT INTO track VALUES(15, 'Boogie Woogie', 3);

As you would expect, it is not possible to manipulate the database to a state
that violates the foreign key constraint by deleting or updating rows in the
artist table either:

sqlite> -- Attempting to delete the artist record for "Frank Sinatra" fails, since
sqlite> -- the track table contains a row that refer to it.
sqlite> DELETE FROM artist WHERE artistname = 'Frank Sinatra';
SQL error: foreign key constraint failed

sqlite> -- Delete all the records from the track table that refer to the artist
sqlite> -- "Frank Sinatra". Only then is it possible to delete the artist.
sqlite> DELETE FROM track WHERE trackname = 'My Way';
sqlite> DELETE FROM artist WHERE artistname = 'Frank Sinatra';

sqlite> -- Try to update the artistid of a row in the artist table while there
sqlite> -- exists records in the track table that refer to it. 
sqlite> UPDATE artist SET artistid=4 WHERE artistname = 'Dean Martin';
SQL error: foreign key constraint failed

sqlite> -- Once all the records that refer to a row in the artist table have
sqlite> -- been deleted, it is possible to modify the artistid of the row.
sqlite> DELETE FROM track WHERE trackname IN('That''s Amore', 'Christmas Blues');
sqlite> UPDATE artist SET artistid=4 WHERE artistname = 'Dean Martin';

SQLite uses the following terminology:

• The parent table is the table that a foreign key constraint
  refers to. The parent table in the example in this section is the
  artist table. Some books and articles refer to this as the
  referenced table, which is arguably more correct, but tends
  to lead to confusion.

• The child table is the table that a foreign key constraint
  is applied to and the table that contains the REFERENCES clause.
  The example in this section uses the track table
  as the child table. Other books and articles refer to this as the
  referencing table.

• The parent key is the column or set of columns in the parent
  table that the foreign key constraint refers to. This is normally, but
  not always, the primary key of the parent table. The parent key must
  be a named column or columns in the parent table, not the rowid.

• The child key is the column or set of columns in the child
  table that are constrained by the foreign key constraint and which
  hold the REFERENCES clause.

The foreign key constraint is satisfied if for each row in the child table
either one or more of the child key columns are NULL, or there exists a
row in the parent table for which each parent key column contains a value
equal to the value in its associated child key column.

In the above paragraph, the term «equal» means equal when values are
compared using the rules specified
here. The following clarifications apply:

• When comparing text values, the collating sequence
  associated with the parent key column is always used.

• When comparing values, if the parent key column has an affinity,
  then that affinity is applied to the child key value before the
  comparison is performed.

2.
Enabling Foreign Key Support

In order to use foreign key constraints in SQLite, the library must
be compiled with neither SQLITE_OMIT_FOREIGN_KEY nor
SQLITE_OMIT_TRIGGER defined. If SQLITE_OMIT_TRIGGER is defined
but SQLITE_OMIT_FOREIGN_KEY is not, then SQLite behaves as it did prior
to version 3.6.19 (2009-10-14)
— foreign key definitions are parsed and may be
queried using PRAGMA foreign_key_list, but foreign key constraints
are not enforced. The PRAGMA foreign_keys command is a no-op in this
configuration. If OMIT_FOREIGN_KEY is defined, then foreign key
definitions cannot even be parsed (attempting to specify a foreign
key definition is a syntax error).

Assuming the library is compiled with foreign key constraints enabled,
it must still be enabled by the application at runtime, using the
PRAGMA foreign_keys command. For example:

sqlite> PRAGMA foreign_keys = ON;

Foreign key constraints are disabled by default
(for backwards compatibility),
so must be enabled separately for each database connection.
(Note, however, that future releases of SQLite might change
so that foreign key constraints enabled by default. Careful
developers will not
make any assumptions about whether or not foreign keys are enabled by
default but will instead enable or disable them as necessary.)
The application can also use a PRAGMA foreign_keys statement to
determine if foreign keys are currently enabled. The following
command-line session demonstrates this:

sqlite> PRAGMA foreign_keys;
0
sqlite> PRAGMA foreign_keys = ON;
sqlite> PRAGMA foreign_keys;
1
sqlite> PRAGMA foreign_keys = OFF;
sqlite> PRAGMA foreign_keys;
0

Tip: If the command «PRAGMA foreign_keys» returns no data instead of a
single row containing «0» or «1», then the version of SQLite you are
using does not support foreign keys (either because it is older than
3.6.19 or because it was compiled with SQLITE_OMIT_FOREIGN_KEY or
SQLITE_OMIT_TRIGGER defined).

It is not possible to enable or disable foreign key constraints
in the middle of a multi-statement transaction (when SQLite
is not in autocommit mode). Attempting to do so does not return
an error; it simply has no effect.

3. Required and Suggested Database Indexes

Usually, the parent key of a foreign key constraint is the primary key of
the parent table. If they are not the primary key, then the parent key
columns must be collectively subject to a UNIQUE constraint or have
a UNIQUE index.
If the parent key columns have a UNIQUE index,
then that index must use the collation sequences that are specified
in the CREATE TABLE statement for the parent table.
For example,

CREATE TABLE parent(a PRIMARY KEY, b UNIQUE, c, d, e, f);
CREATE UNIQUE INDEX i1 ON parent(c, d);
CREATE INDEX i2 ON parent(e);
CREATE UNIQUE INDEX i3 ON parent(f COLLATE nocase);

CREATE TABLE child1(f, g REFERENCES parent(a));                        -- Ok
CREATE TABLE child2(h, i REFERENCES parent(b));                        -- Ok
CREATE TABLE child3(j, k, FOREIGN KEY(j, k) REFERENCES parent(c, d));  -- Ok
CREATE TABLE child4(l, m REFERENCES parent(e));                        -- Error!
CREATE TABLE child5(n, o REFERENCES parent(f));                        -- Error!
CREATE TABLE child6(p, q, FOREIGN KEY(p, q) REFERENCES parent(b, c));  -- Error!
CREATE TABLE child7(r REFERENCES parent(c));                           -- Error!

The foreign key constraints created as part of tables child1,
child2 and child3 are all fine. The foreign key
declared as part of table child4 is an error because even though
the parent key column is indexed, the index is not UNIQUE.
The foreign key for table child5
is an error because even though the parent key column has a unique
index, the index uses a different collating sequence.
Tables child6 and child7 are incorrect because while
both have UNIQUE indices on their parent keys, the keys are not an
exact match to the columns of a single UNIQUE index.

If the database schema contains foreign key errors that require looking
at more than one table definition to identify, then those errors are not
detected when the tables are created. Instead, such errors prevent
the application from preparing SQL statements that modify the content
of the child or parent tables in ways that use the foreign keys.
Errors reported when content is changed are «DML errors» and errors
reported when the schema is changed are «DDL errors».
So, in other words, misconfigured foreign key constraints that require
looking at both the child and parent are DML errors.
The English language error message for foreign key DML errors is usually
«foreign key mismatch» but can also be «no such table» if the parent
table does not exist.
Foreign key DML errors are reported if:

• The parent table does not exist, or
• The parent key columns named in the foreign key constraint do
  not exist, or
• The parent key columns named in the foreign key constraint are not
  the primary key of the parent table and are not subject to a unique
  constraint using collating sequence specified in the CREATE TABLE, or
• The child table references the primary key of the parent without
  specifying the primary key columns and the number of primary key
  columns in the parent do not match the number of child key columns.

The last bullet above is illustrated by the following:

CREATE TABLE parent2(a, b, PRIMARY KEY(a,b));

CREATE TABLE child8(x, y, FOREIGN KEY(x,y) REFERENCES parent2);        -- Ok
CREATE TABLE child9(x REFERENCES parent2);                             -- Error!
CREATE TABLE child10(x,y,z, FOREIGN KEY(x,y,z) REFERENCES parent2);    -- Error!

By contrast, if foreign key errors can be recognized simply by looking
at the definition of the child table and without having to consult the
parent table definition, then the
CREATE TABLE statement for the child table fails. Because the error
occurs during a schema change, this is a DDL error.
Foreign key DDL errors are reported regardless of
whether or not foreign key constraints are enabled when the
table is created.

Indices are not required for child key columns but they are almost
always beneficial. Returning to
the example in section 1, each time an application
deletes a row from the artist table (the parent table), it
performs the equivalent of the following SELECT statement to search
for referencing rows in the track table (the child table).

SELECT rowid FROM track WHERE trackartist = ?

where ? in the above is replaced with the value of the artistid
column of the record being deleted from the artist table (recall
that the trackartist column is the child key and the artistid
column is the parent key). Or, more generally:

SELECT rowid FROM <child-table> WHERE <child-key> = :parent_key_value

If this SELECT returns any rows at all, then SQLite concludes that
deleting the row from the parent table would violate the foreign key
constraint and returns an error.
Similar queries may be run if the content of the parent key
is modified or a new row is inserted into the parent table.
If these queries cannot use an index, they are forced to do a
linear scan of the entire child table. In a non-trivial database, this may
be prohibitively expensive.

So, in most real systems, an index should be created on the child key columns
of each foreign key constraint. The child key index does not have
to be (and usually will not be) a UNIQUE index.
Returning again to the example in section 1, the
complete database schema for efficient implementation of the foreign key
constraint might be:

CREATE TABLE artist(
  artistid    INTEGER PRIMARY KEY, 
  artistname  TEXT
);
CREATE TABLE track(
  trackid     INTEGER,
  trackname   TEXT, 
  trackartist INTEGER REFERENCES artist
);
CREATE INDEX trackindex ON track(trackartist);

The block above uses a shorthand form to create the foreign key constraint.
Attaching a «REFERENCES <parent-table>» clause to a column
definition creates a foreign key constraint that maps the column to the
primary key of <parent-table>. Refer to the CREATE TABLE
documentation for further details.

4. Advanced Foreign Key Constraint Features

4.1. Composite Foreign Key Constraints

A composite foreign key constraint is one where the child and parent keys
are both composite keys. For example, consider
the following database schema:

CREATE TABLE album(
  albumartist TEXT,
  albumname TEXT,
  albumcover BINARY,
  PRIMARY KEY(albumartist, albumname)
);

CREATE TABLE song(
  songid     INTEGER,
  songartist TEXT,
  songalbum TEXT,
  songname   TEXT,
  FOREIGN KEY(songartist, songalbum) REFERENCES album(albumartist, albumname)
);

In this system, each entry in the song table is required to map to an entry
in the album table with the same combination of artist and album.

Parent and child keys must have the same cardinality.
In SQLite, if any of the child key columns (in this case songartist
and songalbum) are NULL, then there is no requirement for a corresponding
row in the parent table.

4.2. Deferred Foreign Key Constraints

Each foreign key constraint in SQLite is classified as either immediate
or deferred. Foreign key constraints are immediate by default.
All the foreign key examples presented
so far have been of immediate foreign key constraints.

If a statement modifies the contents of the database so that an immediate
foreign key constraint is in violation at the conclusion the statement,
an exception is thrown and
the effects of the statement are reverted. By contrast, if
a statement modifies the contents of the database such that a deferred
foreign key constraint is violated, the violation is not reported
immediately. Deferred foreign key constraints are not checked
until the transaction tries to COMMIT.
For as long as the user has
an open transaction, the database is allowed to exist in a state that
violates any number of deferred foreign key constraints. However,
COMMIT will fail as long as foreign key constraints remain in
violation.

If the current statement is not inside an explicit transaction (a
BEGIN/COMMIT/ROLLBACK block), then an implicit
transaction is committed
as soon as the statement has finished executing. In this case deferred
constraints behave the same as immediate constraints.

To mark a foreign key constraint as deferred, its declaration must
include the following clause:

DEFERRABLE INITIALLY DEFERRED                -- A deferred foreign key constraint

The full syntax for specifying foreign key constraints is available as part
of the CREATE TABLE documentation. Replacing the phrase above
with any of the following
creates an immediate foreign key constraint.

NOT DEFERRABLE INITIALLY DEFERRED            -- An immediate foreign key constraint
NOT DEFERRABLE INITIALLY IMMEDIATE           -- An immediate foreign key constraint
NOT DEFERRABLE                               -- An immediate foreign key constraint
DEFERRABLE INITIALLY IMMEDIATE               -- An immediate foreign key constraint
DEFERRABLE                                   -- An immediate foreign key constraint

The defer_foreign_keys pragma can be used to temporarily change all foreign
key constraints to deferred regardless of how they are declared.

The following example illustrates the effect of using a deferred foreign
key constraint.

-- Database schema. Both tables are initially empty. 
CREATE TABLE artist(
  artistid    INTEGER PRIMARY KEY, 
  artistname  TEXT
);
CREATE TABLE track(
  trackid     INTEGER,
  trackname   TEXT, 
  trackartist INTEGER REFERENCES artist(artistid) DEFERRABLE INITIALLY DEFERRED
);

sqlite3> -- If the foreign key constraint were immediate, this INSERT would
sqlite3> -- cause an error (since as there is no row in table artist with
sqlite3> -- artistid=5). But as the constraint is deferred and there is an
sqlite3> -- open transaction, no error occurs.
sqlite3> BEGIN;
sqlite3>   INSERT INTO track VALUES(1, 'White Christmas', 5);

sqlite3> -- The following COMMIT fails, as the database is in a state that
sqlite3> -- does not satisfy the deferred foreign key constraint. The
sqlite3> -- transaction remains open.
sqlite3> COMMIT;
SQL error: foreign key constraint failed

sqlite3> -- After inserting a row into the artist table with artistid=5, the
sqlite3> -- deferred foreign key constraint is satisfied. It is then possible
sqlite3> -- to commit the transaction without error.
sqlite3>   INSERT INTO artist VALUES(5, 'Bing Crosby');
sqlite3> COMMIT;

A nested savepoint transaction may be RELEASEd while the
database is in a state that does not satisfy a deferred foreign key
constraint. A transaction savepoint (a non-nested savepoint that was
opened while there was not currently an open transaction), on the
other hand, is subject to the same restrictions as a COMMIT — attempting
to RELEASE it while the database is in such a state will fail.

If a COMMIT statement (or the RELEASE of a transaction SAVEPOINT) fails
because the database is currently in a state that violates a deferred
foreign key constraint and there are currently
nested savepoints, the nested savepoints remain open.

4.3.
ON DELETE and ON UPDATE Actions

Foreign key ON DELETE and ON UPDATE clauses are used to configure actions
that take place when deleting rows from the parent table (ON DELETE), or
modifying the parent key values of existing rows (ON UPDATE). A single
foreign key constraint may have different actions configured for ON DELETE
and ON UPDATE. Foreign key actions are similar to triggers in many ways.

The ON DELETE and ON UPDATE action associated with each foreign key in an
SQLite database is one of «NO ACTION», «RESTRICT», «SET NULL»,
«SET DEFAULT» or «CASCADE». If an action is not explicitly specified, it
defaults to «NO ACTION».

• NO ACTION: Configuring «NO ACTION» means just that: when a
  parent key is modified or deleted from the database, no special action is
  taken.

• RESTRICT: The «RESTRICT» action means that the application
  is prohibited from deleting (for ON DELETE RESTRICT) or modifying
  (for ON UPDATE RESTRICT) a parent key when there exists one or more child
  keys mapped to it. The difference between the effect of a RESTRICT
  action and normal foreign key constraint enforcement is that the
  RESTRICT action processing happens as soon as the field is updated —
  not at the end of the current statement as it would with an immediate
  constraint, or at the end of the current transaction as it would with
  a deferred constraint.
  Even if the foreign key constraint it is
  attached to is deferred, configuring a RESTRICT action causes SQLite to
  return an error immediately if a parent key with dependent child keys is
  deleted or modified.

• SET NULL: If the configured action is «SET NULL», then when
  a parent key is deleted (for ON DELETE SET NULL) or modified (for ON
  UPDATE SET NULL), the child key columns of all rows in the child table
  that mapped to the parent key are set to contain SQL NULL values.

• SET DEFAULT: The «SET DEFAULT» actions are similar to
  «SET NULL»,
  except that each of the child key columns is set to contain the column’s
  default value instead of NULL. Refer to the CREATE TABLE
  documentation for details on how default values are assigned to table
  columns.

• CASCADE: A «CASCADE» action propagates the delete or update
  operation on the parent key to each dependent child key. For an «ON
  DELETE CASCADE» action, this means that each row in the child table that
  was associated with the deleted parent row is also deleted. For an «ON
  UPDATE CASCADE» action, it means that the values stored in each dependent
  child key are modified to match the new parent key values.

For example, adding an «ON UPDATE CASCADE» clause to the foreign key as
shown below enhances the example schema from section 1 to allow the user
to update the artistid (the parent key of the foreign key constraint)
column without breaking referential integrity:

-- Database schema
CREATE TABLE artist(
  artistid    INTEGER PRIMARY KEY, 
  artistname  TEXT
);
CREATE TABLE track(
  trackid     INTEGER,
  trackname   TEXT, 
  trackartist INTEGER REFERENCES artist(artistid) ON UPDATE CASCADE
);

sqlite> SELECT * FROM artist;
artistid  artistname       
--------  -----------------
1         Dean Martin      
2         Frank Sinatra    

sqlite> SELECT * FROM track;
trackid  trackname          trackartist
-------  -----------------  -----------
11       That's Amore       1
12       Christmas Blues    1
13       My Way             2  

sqlite> -- Update the artistid column of the artist record for "Dean Martin".
sqlite> -- Normally, this would raise a constraint, as it would orphan the two
sqlite> -- dependent records in the track table. However, the ON UPDATE CASCADE clause
sqlite> -- attached to the foreign key definition causes the update to "cascade"
sqlite> -- to the child table, preventing the foreign key constraint violation.
sqlite> UPDATE artist SET artistid = 100 WHERE artistname = 'Dean Martin';

sqlite> SELECT * FROM artist;
artistid  artistname       
--------  -----------------
2         Frank Sinatra    
100       Dean Martin      

sqlite> SELECT * FROM track;
trackid  trackname          trackartist
-------  -----------------  -----------
11       That's Amore       100
12       Christmas Blues    100  
13       My Way             2  

Configuring an ON UPDATE or ON DELETE action does not mean that the foreign
key constraint does not need to be satisfied. For example, if an
«ON DELETE SET DEFAULT» action is configured,
but there is no row in the parent table
that corresponds to the default values of the child key columns, deleting
a parent key while dependent child keys exist still causes a foreign key
violation. For example:

-- Database schema
CREATE TABLE artist(
  artistid    INTEGER PRIMARY KEY, 
  artistname  TEXT
);
CREATE TABLE track(
  trackid     INTEGER,
  trackname   TEXT, 
  trackartist INTEGER DEFAULT 0 REFERENCES artist(artistid) ON DELETE SET DEFAULT
);

sqlite> SELECT * FROM artist;
artistid  artistname       
--------  -----------------
3         Sammy Davis Jr.

sqlite> SELECT * FROM track;
trackid  trackname          trackartist
-------  -----------------  -----------
14       Mr. Bojangles      3

sqlite> -- Deleting the row from the parent table causes the child key
sqlite> -- value of the dependent row to be set to integer value 0. However, this
sqlite> -- value does not correspond to any row in the parent table. Therefore
sqlite> -- the foreign key constraint is violated and an is exception thrown.
sqlite> DELETE FROM artist WHERE artistname = 'Sammy Davis Jr.';
SQL error: foreign key constraint failed

sqlite> -- This time, the value 0 does correspond to a parent table row. And
sqlite> -- so the DELETE statement does not violate the foreign key constraint
sqlite> -- and no exception is thrown.
sqlite> INSERT INTO artist VALUES(0, 'Unknown Artist');
sqlite> DELETE FROM artist WHERE artistname = 'Sammy Davis Jr.';

sqlite> SELECT * FROM artist;
artistid  artistname       
--------  -----------------
0         Unknown Artist

sqlite> SELECT * FROM track;
trackid  trackname          trackartist
-------  -----------------  -----------
14       Mr. Bojangles      0

Those familiar with SQLite triggers
will have noticed that the
«ON DELETE SET DEFAULT» action demonstrated in the example above is
similar in effect to the following AFTER DELETE trigger:

CREATE TRIGGER on_delete_set_default AFTER DELETE ON artist BEGIN
  UPDATE child SET trackartist = 0 WHERE trackartist = old.artistid;
END;

Whenever a row in the parent table of a foreign key constraint is deleted,
or when the values stored in the parent key column or columns are modified,
the logical sequence of events is:

1. Execute applicable BEFORE trigger programs,
2. Check local (non foreign key) constraints,
3. Update or delete the row in the parent table,
4. Perform any required foreign key actions,
5. Execute applicable AFTER trigger programs.

There is one important difference between ON UPDATE foreign key actions and
SQL triggers. An ON UPDATE action is only taken if the values of the
parent key are modified so that the new parent key values are
not equal to the old. For example:

-- Database schema
CREATE TABLE parent(x PRIMARY KEY);
CREATE TABLE child(y REFERENCES parent ON UPDATE SET NULL);

sqlite> SELECT * FROM parent;
x
----
key

sqlite> SELECT * FROM child;
y
----
key

sqlite> -- Since the following UPDATE statement does not actually modify
sqlite> -- the parent key value, the ON UPDATE action is not performed and
sqlite> -- the child key value is not set to NULL.
sqlite> UPDATE parent SET x = 'key';
sqlite> SELECT IFNULL(y, 'null') FROM child;
y
----
key

sqlite> -- This time, since the UPDATE statement does modify the parent key
sqlite> -- value, the ON UPDATE action is performed and the child key is set
sqlite> -- to NULL.
sqlite> UPDATE parent SET x = 'key2';
sqlite> SELECT IFNULL(y, 'null') FROM child;
y
----
null

5. CREATE, ALTER and DROP TABLE commands

This section describes the way the CREATE TABLE, ALTER TABLE,
and DROP TABLE commands
interact with SQLite’s foreign keys.

A CREATE TABLE command operates the same whether or not
foreign key constraints are enabled. The parent key definitions of
foreign key constraints are not checked when a table is created. There is
nothing stopping the user from creating a foreign key definition that
refers to a parent table that does not exist, or to parent key columns that
do not exist or are not collectively bound by a PRIMARY KEY or UNIQUE
constraint.

The ALTER TABLE command works differently in two respects when foreign
key constraints are enabled:

• It is not possible to use the «ALTER TABLE … ADD COLUMN» syntax
  to add a column that includes a REFERENCES clause, unless the default
  value of the new column is NULL. Attempting to do so returns an
  error.

• If an «ALTER TABLE … RENAME TO» command is used to rename a table
  that is the parent table of one or more foreign key constraints, the
  definitions of the foreign key constraints are modified to refer to
  the parent table by its new name. The text of the child CREATE
  TABLE statement or statements stored in the sqlite_schema table are
  modified to reflect the new parent table name.

If foreign key constraints are enabled when it is prepared, the
DROP TABLE command performs an implicit DELETE to remove all
rows from the table before dropping it. The implicit DELETE does not cause
any SQL triggers to fire, but may invoke foreign key actions or constraint
violations. If an immediate foreign key constraint is violated, the DROP
TABLE statement fails and the table is not dropped. If a deferred foreign
key constraint is violated, then an error is reported when the user attempts
to commit the transaction if the foreign key constraint violations still
exist at that point. Any «foreign key mismatch» errors encountered as part
of an implicit DELETE are ignored.

The intent of these enhancements to the ALTER TABLE and DROP TABLE
commands is to ensure that they cannot be used to create a database that
contains foreign key violations, at least while foreign key constraints are
enabled. There is one exception to this rule though. If a parent key is
not subject to a PRIMARY KEY or UNIQUE constraint created as part of the
parent table definition, but is subject to a UNIQUE constraint by virtue
of an index created using the CREATE INDEX command, then the child
table may be populated without causing a «foreign key mismatch» error. If
the UNIQUE index is dropped from the database schema, then the parent table
itself is dropped, no error will be reported. However the database may be
left in a state where the child table of the foreign key constraint contains
rows that do not refer to any parent table row. This case can be avoided
if all parent keys in the database schema are constrained by PRIMARY KEY
or UNIQUE constraints added as part of the parent table definition, not
by external UNIQUE indexes.

The properties of the DROP TABLE and ALTER TABLE commands described
above only apply if foreign keys are enabled. If the user considers them
undesirable, then the workaround is to use PRAGMA foreign_keys to
disable foreign key constraints before executing the DROP or ALTER TABLE
command. Of course, while foreign key constraints are disabled, there is nothing
to stop the user from violating foreign key constraints and thus creating
an internally inconsistent database.

6. Limits and Unsupported Features

This section lists a few limitations and omitted features that are not
mentioned elsewhere.

1. No support for the MATCH clause. According to SQL92, a MATCH clause
   may be attached to a composite foreign key definition to modify the way
   NULL values that occur in child keys are handled. If «MATCH SIMPLE» is
   specified, then a child key is not required to correspond to any row
   of the parent table if one or more of the child key values are NULL.
   If «MATCH FULL» is specified, then if any of the child key values is
   NULL, no corresponding row in the parent table is required, but all
   child key values must be NULL. Finally, if the foreign key constraint
   is declared as «MATCH PARTIAL» and one of the child key values is NULL,
   there must exist at least one row in the parent table for which the
   non-NULL child key values match the parent key values.

   SQLite parses MATCH clauses (i.e. does not report a syntax error
   if you specify one), but does not enforce them. All foreign key
   constraints in SQLite are handled as if MATCH SIMPLE were specified.

2. No support for switching constraints between deferred and immediate
   mode. Many systems allow the user to toggle individual foreign key
   constraints between deferred and immediate
   mode at runtime (for example using the Oracle «SET CONSTRAINT» command).
   SQLite does not support this. In SQLite, a foreign key constraint is
   permanently marked as deferred or immediate when it is created.

3. Recursion limit on foreign key actions. The
   SQLITE_MAX_TRIGGER_DEPTH and SQLITE_LIMIT_TRIGGER_DEPTH
   settings determine the maximum allowable depth of trigger
   program recursion. For the purposes of these limits,
   foreign key actions are considered trigger programs. The
   PRAGMA recursive_triggers setting does not affect the operation
   of foreign key actions. It is not possible to disable recursive foreign
   key actions.

CREATE TABLE "student_table" (
    "student_id"    INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
    "name"  TEXT NOT NULL,
    "gender"    TEXT NOT NULL,
    "year_admited"  INTEGER
);

CREATE TABLE "year_table" (
    "year"  INTEGER NOT NULL,
    "student_id"    INTEGER NOT NULL,
    "class" INTEGER NOT NULL,
    PRIMARY KEY("year"),
    FOREIGN KEY("student_id") REFERENCES "student_table"("student_id")
);

CREATE TABLE "terms_table" (
    "year"  INTEGER NOT NULL,
    "student_id"    INTEGER NOT NULL,
    "term"  INTEGER NOT NULL,
    "fees"  INTEGER,
    PRIMARY KEY("term","year"),
    FOREIGN KEY("year") REFERENCES "year_table"("year"),
    FOREIGN KEY("student_id") REFERENCES "year_table"("student_id")
);

INSERT INTO "main"."terms_table"
("year", "student_id", "term", "fees")
VALUES (2020, 1, 1, 900000);

Error adding record. Message from database engine:

foreign key mismatch - "terms_table" referencing "year_table" (INSERT INTO 
"main"."terms_table"
("year", "student_id", "term", "fees")
VALUES (2020, 1, 1, 900000);)

1 ответ

Лучший ответ

FOREIGN KEY("student_id") REFERENCES "year_table"("student_id")

FOREIGN KEY("student_id") REFERENCES "student_table"("student_id")