postgresql 获取主键字段

select pg_constraint.conname as pk_name,pg_attribute.attname as colname,pg_type.typname as typename from
pg_constraint  inner join pg_class
on pg_constraint.conrelid = pg_class.oid
inner join pg_attribute on pg_attribute.attrelid = pg_class.oid
and  pg_attribute.attnum = pg_constraint.conkey[1]
inner join pg_type on pg_type.oid = pg_attribute.atttypid
where pg_class.relname = 'yourtablename'
and pg_constraint.contype='p'