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MySQL 5.5 Reference Manual :: 19 INFORMATION_SCHEMA Tables :: 19.12 The INFORMATION_SCHEMA TABLE_CONSTRAINTS Table
19.13 The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table »
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19.12. The INFORMATION_SCHEMA TABLE_CONSTRAINTS Table

The TABLE_CONSTRAINTS table describes which tables have constraints.

INFORMATION_SCHEMA Name SHOW Name Remarks
CONSTRAINT_CATALOG   def
CONSTRAINT_SCHEMA    
CONSTRAINT_NAME    
TABLE_SCHEMA    
TABLE_NAME    
CONSTRAINT_TYPE    

Notes:

  • The CONSTRAINT_TYPE value can be UNIQUE, PRIMARY KEY, or FOREIGN KEY.

  • The UNIQUE and PRIMARY KEY information is about the same as what you get from the Key_name field in the output from SHOW INDEX when the Non_unique field is 0.

  • The CONSTRAINT_TYPE column can contain one of these values: UNIQUE, PRIMARY KEY, FOREIGN KEY, CHECK. This is a CHAR (not ENUM) column. The CHECK value is not available until we support CHECK.