Tag: FOREIGN KEY
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Post Views: 22 1. When deleting the table in MySQL, an error is reported: 1217 – Cannot delete or update a parent row: a foreign key constraaint fail. as shown in Figure 1 2. Reference:You can get information about foreign keys from information_schema.key_column_usagetable. The query example for that table is shown here . as shown in Figure 2 3. The…
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Post Views: 16 1. Error when adding foreign key constraints: sqlstate[23000]: Integrity Constraint Violation: 1452 cannot add or update a child row: a foreign key constraint fails . as shown in Figure 1 2. Analyze the reason, the record of the user ID equal to 9 exists in the topics, but it no longer exists in users. as shown in…