postgresql 的 show create table 命令

mysql 的 show create table 非常棒，
下面转载 https://blog.csdn.net/xiaofengtoo/article/details/84395199

CREATE OR REPLACE FUNCTION findattname(
  namespace character varying, 
  tablename character varying, 
  ctype character varying
)
RETURNS character varying AS
$BODY$
declare
  tt oid ;
  aname character varying default '';
begin
    tt := oid from pg_class where relname= tablename 
	and relnamespace =(select oid from pg_namespace  where nspname=namespace) ;
	-- select oid from pg_namespace where nspowner=(select datdba from pg_database where datname=namespace)
      
       aname:=  array_to_string(
		array(
		       select a.attname  from pg_attribute  a 
				where a.attrelid=tt and  a.attnum   in (		
				select unnest(conkey) from pg_constraint c where contype=ctype 
				and conrelid=tt  and array_to_string(conkey,',') is not null  
			) 
		),',')
	;
	return aname;
end 
$BODY$
LANGUAGE plpgsql VOLATILE
  COST 100;
  

CREATE OR REPLACE FUNCTION showcreatetable(
  namespace character varying, 
  tablename character varying
)
RETURNS character varying AS
$BODY$
declare 
    tableScript character varying default '';
begin
	-- columns
	tableScript:=tableScript || ' CREATE TABLE '|| tablename|| ' ( '|| array_to_string(
	  array(
	select concat( c1, c2, c3, c4, c5, c6 ) as column_line
	from (
	  select column_name || ' ' || data_type 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 '(' || numeric_precision || ')' end as c3,
		case when numeric_precision > 0 and numeric_scale > 0 then '(' || numeric_precision || ', ' || numeric_scale || ')' 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_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(namespace,tablename,'u') ) ||')' end as u ,
			case when contype='p' then ' PRIMARY KEY ('|| ( select findattname(namespace,tablename,'p') ) ||')' end  as p  ,
			case when contype='f' then ' FOREIGN KEY('|| ( select findattname(namespace,tablename,'u') ) ||') REFERENCES '|| 
			(select p.relname from pg_class p where p.oid=c.confrelid )  || '('|| ( select findattname(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=namespace)
				)
			 )
		) as t  
	) ,',' ) || ' ); ';
	
	-- indexs 
	 
	-- CREATE UNIQUE INDEX pg_language_oid_index ON pg_language USING btree (oid); -- table pg_language
	 
	 
	-- 
	/** **/
	--- 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 UNIQUE INDEX ' || indexrelname || ' ON ' || tablename || ' USING btree '|| '(' || 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
				
			   FROM pg_class c
			   JOIN pg_index x ON c.oid = x.indrelid
			   JOIN pg_class i ON i.oid = x.indexrelid
			   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  )
			)as t
	) ,',' );
			
 
	-- COMMENT COMMENT ON COLUMN sys_activity.id IS '主键';
	tableScript:= tableScript || array_to_string(
	array(
	SELECT ' COMMENT ON COLUMN' || tablename || '.' || a.attname ||' IS  '|| ''''|| d.description ||''''
	FROM pg_class c
	JOIN pg_description d ON c.oid=d.objoid
	JOIN pg_attribute a ON c.oid = a.attrelid
	WHERE c.relname=tablename
	AND a.attnum = d.objsubid),',') ;
	 
    return tableScript;
 
end
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
  
  

查看定义

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