--数据库、模式、表名 "identities"."Test"."tab_test"

--修改字段名

ALTER TABLE "identities"."Test"."tab_test"  RENAME "u_name"  to realname ;

--添加字段

ALTER TABLE "identities"."Test"."tab_test"  ADD COLUMN updcontent  VARCHAR(50);

--添加字段  给默认值

ALTER TABLE "identities"."Test"."tab_test"   ADD COLUMN utype  INT DEFAULT(1);

--字段注解

COMMENT ON COLUMN "identities"."Test"."tab_test"."utype"  IS '类型 1为普通 2为高级';

--修改字段类型

ALTER TABLE "identities"."Test"."tab_test" alter  COLUMN  utype  type VARCHAR(50) ;

--删除非空约束

ALTER TABLE "identities"."Test"."tab_test"  ALTER COLUMN realname  drop not    NULL;

--添加主键

ALTER TABLE "identities"."Test"."tab_test"  ADD PRIMARY KEY ("id");