查询格式：

SELECT
c.relname 表名称,
A.attname AS 字段名称,
col_description(A.attrelid,A.attnum) AS 注释,
format_type ( A.atttypid, A.atttypmod ) AS 类型,
CASE WHEN A.attnotnull=’f’ THEN ‘否’ ELSE ‘是’ END AS 是否必填,
a.attnum 序号
FROM
pg_class AS c,
pg_attribute AS a
WHERE
A.attrelid = C.oid
AND A.attnum > 0
ORDER BY c.relname,a.attnum;