postgresql11 查看表结构和系统视图

postgres=# select * from pg_tables where tablename='t';
 schemaname | tablename | tableowner | tablespace | hasindexes | hasrules | hastriggers | rowsecurity 
------------+-----------+------------+------------+------------+----------+-------------+-------------
 public     | t         | postgres   |            | t          | f        | f           | f
(1 row)

postgres-# \d t
                        Table "public.t"
 Column |         Type          | Collation | Nullable | Default 
--------+-----------------------+-----------+----------+---------
 id     | integer               |           | not null | 
 name   | character varying(20) |           |          | 
Indexes:
    "t_pkey" PRIMARY KEY, btree (id)

sql语句查看表结构
SELECT A
	.attnum,
	A.attname AS field,
	T.typname AS TYPE,
	A.attlen AS LENGTH,
	A.atttypmod AS lengthvar,
	A.attnotnull 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 = 't' 
	AND A.attnum > 0 
	AND A.attrelid = C.oid 
	AND A.atttypid = T.oid 
ORDER BY
	A.attnum;　

查看系统视图

postgres-# \df pg_last*
                                                          List of functions
   Schema   |             Name              |     Result data type     |                  Argument data types                  | Type 
------------+-------------------------------+--------------------------+-------------------------------------------------------+------
 pg_catalog | pg_last_committed_xact        | record                   | OUT xid xid, OUT "timestamp" timestamp with time zone | func
 pg_catalog | pg_last_wal_receive_lsn       | pg_lsn                   |                                                       | func
 pg_catalog | pg_last_wal_replay_lsn        | pg_lsn                   |                                                       | func
 pg_catalog | pg_last_xact_replay_timestamp | timestamp with time zone |                                                       | func
(4 rows)

　　

系统视图 官方链接

https://www.postgresql.org/docs/current/catalogs.html

生成建表sql语句

CREATE OR REPLACE FUNCTION "public"."showcreatetable"("dbinstancename" varchar, "namespace" varchar, "tablename" varchar, "tenantid" varchar)
  RETURNS "pg_catalog"."varchar" AS $BODY$
declare 
tableScript character varying default '';
tableNum int2 ;
 
begin
-- check db extist
tableNum:= count(*)    from pg_class  where relname=tablename and relnamespace =(
            select oid from pg_namespace where nspowner=(select datdba from pg_database where datname=dbinstancename) and nspname = namespace
            );
IF tableNum=0  then 
return '' ;
end if;
-- columns
tableScript:=tableScript || ' CREATE TABLE IF NOT EXISTS '|| '"sch_'||tenantid||'".'||tablename|| ' ( '|| array_to_string(
  array(
select concat( c1, c2, c3, c4, c5, c6 ) as column_line
from (
  select '"'||column_name||'"' || ' ' || case when data_type='ARRAY' then ltrim(udt_name,'_')||'[]' else data_type end as c1,
    case when character_maximum_length > 0 then '(' || character_maximum_length || ')' end as c2,
    case when numeric_precision > 0 and numeric_scale < 1 then null end as c3,
    case when numeric_precision > 0 and numeric_scale > 0 then null end as c4,
    case when is_nullable = 'NO' then ' NOT NULL' end as c5,
    case when column_default is not Null then ' DEFAULT' end || ' ' || replace(column_default, '::character varying', '') as c6
  from information_schema.columns
  where table_name = tablename
    and table_catalog=dbinstancename
  and table_schema=namespace
  order by ordinal_position
) as string_columns
),' , ') ||',' ;
 
 
-- 约束
tableScript:= tableScript || array_to_string(
array(
    select concat(' CONSTRAINT ','"'||conname||'"' ,c ,u,p,f)   from (
        select conname,
        case when contype='c' then  ' CHECK('|| consrc ||')' end  as c  ,
        case when contype='u' then  ' UNIQUE('|| ( select findattname(dbinstancename,namespace,tablename,'u') ) ||')' end as u ,
        case when contype='p' then ' PRIMARY KEY ('|| ( select findattname(dbinstancename,namespace,tablename,'p') ) ||')' end  as p  ,
        case when contype='f' then ' FOREIGN KEY('|| ( select findattname(dbinstancename,namespace,tablename,'u') ) ||') REFERENCES '|| 
        (select p.relname from pg_class p where p.oid=c.confrelid )  || '('|| ( select findattname(dbinstancename,namespace,tablename,'u') ) ||')' end as  f
        from pg_constraint c
        where contype in('u','c','f','p') and conrelid=( 
            select oid  from pg_class  where relname=tablename and relnamespace =(
            select oid from pg_namespace where nspowner=(select datdba from pg_database where datname=dbinstancename) and nspname = namespace
            )
         )
    ) as t  
) ,',' ) || ' ); '; 
 
-- 
/** **/
--- 获取非约束索引 column
-- CREATE UNIQUE INDEX pg_language_oid_index ON pg_language USING btree (oid); -- table pg_language
tableScript:= tableScript || array_to_string(
    array(
        select 'CREATE '||case when is_unique_index=true then 'UNIQUE INDEX' else 'INDEX' end ||'"' || indexrelname ||'"' || ' ON ' || '"sch_'||tenantid||'".'||tablename|| ' USING '||index_type|| '(' || attname || ');' from (
         SELECT 
            i.relname AS indexrelname ,  x.indkey, 
            ( select array_to_string (
            array( 
                select a.attname from pg_attribute a where attrelid=c.oid and a.attnum in ( select unnest(x.indkey) )
 
                 ) 
             ,',' ) )as attname, x.indisunique is_unique_index,am.amname index_type
            
           FROM pg_class c
           JOIN pg_index x ON c.oid = x.indrelid
           JOIN pg_class i ON i.oid = x.indexrelid
             join pg_am am on am.oid = i.relam
           LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
           WHERE  c.relname=tablename and i.relname not in
              ( select constraint_name from information_schema.key_column_usage  where  table_name=tablename  )
                and c.relnamespace =(
            select oid from pg_namespace where nspowner=(select datdba from pg_database where datname=dbinstancename) and nspname = namespace
            )
        )as t
) ,'' );
            

 
return tableScript;
 
end
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100
 

查看建表语句

select showcreatetable('public','pub_eventlistener');