The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table The name of the catalog to which the constraint belongs. This value is always  def . The name of the schema (database) to which the constraint belongs. The name of the constraint. The name of the catalog to which the table belongs. This value is always  def . The name of the schema (database) to which the table belongs. The name of the table that has the constraint. The name of the column that has the constraint. If the constraint is a foreign key, then this is the column of the foreign key, not the column that the foreign key references. The column’s position within the constraint, not the column’s position within the table. Column positions are numbered beginning with 1. NULL  for unique and primary-key constraints. For foreign-key constraints, this column is the ordinal position in key of the table that is being referenced. The name of the column referenced by the constraint. The name of the table referenced by the constraint. The name of the schema referenced by the constraint. Suppose that there are two tables name  t1  and  t3  that have the following definitions: 4800 CREATE TABLE t1 ( s1 INT, s2 INT, s3 INT, PRIMARY KEY(s3) ) ENGINE=InnoDB; • REFERENCED_COLUMN_NAME • REFERENCED_TABLE_NAME • REFERENCED_TABLE_SCHEMA • POSITION_IN_UNIQUE_CONSTRAINT • ORDINAL_POSITION • COLUMN_NAME • TABLE_NAME • TABLE_SCHEMA • TABLE_CATALOG • CONSTRAINT_NAME • CONSTRAINT_SCHEMA