postgresql用sql查询表结构

查询sql如下：

SELECT 
a.attname AS field,
t.typname AS type,
CASE WHEN t.typlen = -1 THEN a.atttypmod - 4 ELSE t.typlen::integer END AS lengthvar,
case a.attnotnull when 't' then 'NO' else 'YES' end AS notnull,
b.description AS comment
FROM pg_class c,
pg_attribute a
LEFT OUTER JOIN pg_description b ON a.attrelid=b.objoid AND a.attnum = b.objsubid,
pg_type t
WHERE c.relname = 'data_air_site_day'
and a.attnum > 0
and a.attrelid = c.oid
and a.atttypid = t.oid
ORDER BY a.attnum;