pgsql中常用

--添加字段和備註
alter table prm_letter_merge add    varchar(324) DEFAULT null;
alter table prm_letter_merge add url2  varchar(324) DEFAULT null;
 COMMENT ON COLUMN public.prm_letter_merge.url1 IS '雲存儲路徑';
 COMMENT ON COLUMN public.prm_letter_merge.url2 IS '雲存儲路徑';
 --修改字段長度
 ALTER TABLE prm_letter_merge MODIFY COLUMN url varchar(900);
 ALTER TABLE prm_letter_merge alter COLUMN url type character varying(1000);
 --刪除字段
 ALTER TABLE prm_letter_merge DROP COLUMN url1;
 ALTER TABLE prm_letter_merge DROP COLUMN url2;
 --創建索引
 Create  Index bill_id_prm_prom_bill_index on prm_prom_bill(bill_id);