select 'DO $$  BEGIN   BEGIN   ALTER TABLE '||relname||' ADD COLUMN recordyear int4;       EXCEPTION            WHEN duplicate_column THEN RAISE NOTICE ''column recordyear already exists'';   END; END;$$;'  as tabname from pg_class c 
where  relkind = 'r' and relname like 'j%_r' and relname not like 'pg_%' and relname not like 'sql_%'  order by relname;



select 'update ' || relname  || ' set recordyear=2019;' as sqlstr from pg_class c 
where  relkind = 'r' and relname like 'j%_r' and relname not like 'pg_%' and relname not like 'sql_%'  order by relname;



-- 设置默认值
select 'DO $$  BEGIN   BEGIN   ALTER TABLE '||relname||' ALTER COLUMN recordyear  SET DEFAULT 2020;       EXCEPTION            WHEN duplicate_column THEN RAISE NOTICE ''column recordyear already exists'';   END; END;$$;'  as tabname from pg_class c 
where  relkind = 'r' and relname like 'j%_r' and relname not like 'pg_%' and relname not like 'sql_%'  order by relname;


-- 删除默认值
ALTER TABLE table_name ALTER COLUMN column_name DROP DEFAULT;


select 'alter table '||pg_class.relname || ' drop constraint '|| pg_constraint.conname ||';' as pk_name from 
pg_constraint  inner join pg_class 
on pg_constraint.conrelid = pg_class.oid 
inner join pg_attribute on pg_attribute.attrelid = pg_class.oid 
and  pg_attribute.attnum = pg_constraint.conkey[1]
inner join pg_type on pg_type.oid = pg_attribute.atttypid where pg_attribute.attname='rowid'
-- where pg_class.relname = 'teacher' 
and pg_constraint.contype='p'