select 
(select relname from  pg_class where oid=a.attrelid) relname ,
(select relname||‘--‘||(select description  from pg_description where objoid=oid and objsubid=0) as comment from pg_class where oid=a.attrelid) as table_name,

a.attname as column_name,

format_type(a.atttypid,a.atttypmod) as data_type,

(
 
case when atttypmod-4>0 then atttypmod-4 else 0 end)data_length,

(case when (select count(*) from pg_constraint where conrelid = a.attrelid and conkey[1]=attnum and contype=‘p‘)>0 then ‘Y‘ else ‘N‘ end) as 主鍵約束,

(case when (select count(*) from pg_constraint where conrelid = a.attrelid and conkey[
 
1]=attnum and contype=‘u‘)>0 then ‘Y‘ else ‘N‘ end) as 唯一約束,

(case when (select count(*) from pg_constraint where conrelid = a.attrelid and conkey[1]=attnum and contype=‘f‘)>0 then ‘Y‘ else ‘N‘ end) as 外鍵約束,

(case when a.attnotnull=true then ‘Y‘ else ‘N‘ end) as nullable,

col_description(a.attrelid,a.attnum) 
 
as comment

from pg_attribute a

where attstattarget=-1 and attrelid in (select oid from pg_class where relname in(select relname from pg_class where relkind =‘r‘ and relname not like ‘pg_%‘ ))

order by relname,a.attnum;

PostgreSql 查詢表結構和說明