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). 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).
The following command-line session demonstrates this: sqlite> PRAGMA foreign_keys Since SQLite uses local files, it does not require a database server. This package implements a contact form manager that stores messages in an SQLite database. A foreign key with a cascade delete can only be defined in a CREATE TABLE statement. 2 hours ago &0183 &32 Contact forms are prevalent features many sites have to let users contact the site managers to send important messages. This is called a cascade delete in SQLite. 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 can also use a PRAGMA foreign_keys statement to determine if foreign keys are currently enabled. What is a Foreign Dey with Cascade Delete in SQLite A foreign key with cascade delete means that if a record in the parent table is deleted, then the corresponding records in the child table will automatically be deleted. (Note, however, that future releases of SQLite might change so that foreign key constraints enabled by default. For example: sqlite> PRAGMA foreign_keys = ON įoreign key constraints are disabled by default (for backwards compatibility), so must be enabled separately for each database connection separately.
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.
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