SQL query to find Primary Key of a table?

Question

How can I find which column is the primary key of a table by using a query?

Answer 1

For MySQL:

SELECT GROUP_CONCAT(COLUMN_NAME), TABLE_NAME
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE
  TABLE_SCHEMA = '**database name**'
  AND CONSTRAINT_NAME='PRIMARY'
GROUP BY TABLE_NAME;

Warning a primary key with two columns will have them separated by a coma (,)