odbc_foreignkeys() retrieves information about
foreign keys. Returns an ODBC result identifier or
FALSE on failure.
The result set has the following columns:
If pk_table contains a table name, odbc_foreignkeys() returns a result set containing the primary key of the specified table and all of the foreign keys that refer to it.
If fk_table contains a table name, odbc_foreignkeys() returns a result set containing all of the foreign keys in the specified table and the primary keys (in other tables) to which they refer.
If both pk_table and fk_table contain table names, odbc_foreignkeys() returns the foreign keys in the table specified in fk_table that refer to the primary key of the table specified in pk_table. This should be one key at most.