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The basic algorithm for this task would be as follows: for each table in the schema. for each column in the table. look for another table whose name and primary key name match the current column name. if such a table is found, add a foreign key referencing it.
1.7.2.3 FOREIGN KEY Constraint Differences. The MySQL implementation of foreign key constraints differs from the SQL standard in the following key respects: If there are several rows in the parent table with the same referenced key value, InnoDB performs a foreign key check as if the other parent rows with the same key value do not exist.
14 paź 2008 · If you can't seem to get any foreign keys to show up after adding them it's probably because your tables are using MyISAM. To check: SELECT * TABLE_NAME, ENGINE FROM information_schema.TABLES WHERE TABLE_SCHEMA = '<yourschema>';
You are advised to use foreign keys that reference only UNIQUE (including PRIMARY) and NOT NULL keys. For storage engines that do not support foreign keys (such as MyISAM), MySQL Server parses and ignores foreign key specifications.
3.6.6 Using Foreign Keys. In MySQL, InnoDB tables support checking of foreign key constraints. See Chapter 15, The InnoDB Storage Engine, and Section 1.7.2.3, “FOREIGN KEY Constraint Differences”. A foreign key constraint is not required merely to join two tables.
A solution to fix this problem is to use the Oracle foreign key constraint to enforce the relationship between rows from the supplier_groups and suppliers tables. First, drop the suppliers table: DROP TABLE suppliers; Code language: SQL (Structured Query Language) (sql) Second, recreate the suppliers table with a foreign key constraint:
7 mar 2023 · If you are still using MyISAM as the storage engine for your tables, it might be time to consider migrating to InnoDB. InnoDB offers several advantages over MyISAM: MVCC, support for ACID transactions, row-level locking, crash recovery capabilities, foreign keys, hot backups, clone.
