PDF (US Ltr)
- 35.1Mb
PDF (A4)
- 35.2Mb
Man Pages (TGZ)
- 256.4Kb
Man Pages (Zip)
- 361.2Kb
Info (Gzip)
- 3.4Mb
Info (Zip)
- 3.4Mb
Search Results
https://dev.mysql.com/doc/refman/5.7/en/create-table-foreign-keys.html
MySQL supports foreign keys, which permit cross-referencing related data across tables, and foreign key constraints, which help keep the related data consistent. If the CONSTRAINT symbol clause is not defined, or a symbol is not included following ...A foreign key relationship involves a parent table that holds the initial column values, and a child table with column values that reference the parent column ...
https://dev.mysql.com/doc/refman/5.7/en/constraint-foreign-key.html
Foreign keys let you cross-reference related data across tables, and foreign key constraints help keep this spread-out data consistent. Since MySQL does not support deferred constraint checking, NO ACTION is treated as RESTRICT. For the exact ...
https://dev.mysql.com/doc/refman/5.7/en/constraint-primary-key.html
Normally, errors occur for data-change statements (such as INSERT or UPDATE) that would violate primary-key, unique-key, or foreign-key constraints. If you are using a transactional storage engine such as InnoDB, MySQL automatically rolls back the ...
https://dev.mysql.com/doc/refman/5.7/en/constraints.html
Because of this, constraint handling is a bit different in MySQL than in other DBMSs. The following sections describe how MySQL Server handles different types of constraints. MySQL enables you to work both with transactional tables that permit ...
https://dev.mysql.com/doc/refman/5.7/en/constraint-enum.html
Unless strict mode is disabled (not recommended, but see Section 5.1.10, “Server SQL Modes”), the definition of a ENUM or SET column acts as a constraint on values entered into the column. ENUM and SET columns provide an efficient way to define ...
https://dev.mysql.com/doc/refman/5.7/en/constraint-invalid-data.html
Invalid values for ENUM and SET columns are handled as described in Section 1.6.3.4, “ENUM and SET Constraints”. MySQL 5.7.5 and later uses strict SQL mode by default, which treats invalid values such that the server rejects them and aborts the ...
https://dev.mysql.com/doc/refman/5.7/en/information-schema-referential-constraints-table.html
The REFERENTIAL_CONSTRAINTS table has these columns: CONSTRAINT_CATALOG The name of the catalog to which the constraint belongs. CONSTRAINT_SCHEMA The name of the schema (database) to which the constraint belongs. UNIQUE_CONSTRAINT_CATALOG The name ...The possible values are CASCADE, SET NULL, SET DEFAULT, RESTRICT, NO ...
https://dev.mysql.com/doc/refman/5.7/en/glossary.html
For example, for a column with a unique constraint, the number of different values is equal to the number of rows in the table. See Also column, composite index, index, index hint, persistent statistics, random dive, selectivity, unique constraint.
https://dev.mysql.com/doc/refman/5.7/en/ansi-diff-foreign-keys.html
For example, if you define a RESTRICT type constraint, and there is a child row with several parent rows, InnoDB does not permit the deletion of any of the parent rows. In an SQL statement that inserts, deletes, or updates many rows, foreign key ...
https://dev.mysql.com/doc/refman/5.7/en/information-schema-table-constraints-table.html
The TABLE_CONSTRAINTS table has these columns: CONSTRAINT_CATALOG The name of the catalog to which the constraint belongs. CONSTRAINT_SCHEMA The name of the schema (database) to which the constraint belongs. TABLE_SCHEMA The name of the schema ...