SELECT 
 c.is_nullable,
 c.data_type,
 c.column_name,
 tc.constraint_type 
FROM 
 information_schema.columns c
LEFT OUTER JOIN 
 information_schema.table_constraints tc
ON
 tc.table_name=c.table_name and
 tc.constraint_type='PRIMARY KEY'
LEFT OUTER JOIN
 information_schema.key_column_usage kcu
ON
 c.column_name=kcu.column_name
WHERE
 c.table_name='test_table'