how to check whether the column is set to primary key ?

[Alvin chew]

hi, how do we use coding to check whether the column have set to primary key ? thank you !

[Paul Sturrock]

A PK is a database constraint. You cannot insert null into it. So the check is implicit to its purpose, and performed by teh DB. If you are worried about trying to run JDBC code which might be inserting nulls into PK fields, just check for nulls as you would normally before trying to run the code.

[Alvin chew]

thank you, paul for reply ..

can we unset the primary key in column which already set as primary key ?

thank you !

[Paul Sturrock]

Just remove the constraint in the DDL.

[Stefan Wagner]

A not-null column needn't be a primary key, while a primary key might not be null.
start:

DatabaseMetaData dbmd = connection.getMetaData();
ResultSet rs = dbmd.getPrimaryKeys (catalog, schema, table);

(catalog, schema, table as String), catalog and schema may be null.
See the javadocs for DatabaseMetaData for more detailed information.