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| Тема |
 RTFM [re: SQL user] |
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| Автор |
Topбaлaн (любопитко) |
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| Публикувано | 03.11.02 17:19 |
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ko pishe ?
7.5.4.2 Foreign Key Constraints
Starting from version 3.23.43b InnoDB features foreign key constraints. InnoDB is the first MySQL table type which allows you to define foreign key constraints to guard the integrity of your data.
The syntax of a foreign key constraint definition in InnoDB:
[CONSTRAINT symbol] FOREIGN KEY (index_col_name, ...)
REFERENCES table_name (index_col_name, ...)
[ON DELETE CASCADE | ON DELETE SET NULL]
Both tables have to be InnoDB type and there must be an index where the foreign key and the referenced key are listed as the first columns. InnoDB does not auto-create indexes on foreign keys or referenced keys: you have to create them explicitly.
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