数据仓库服务 GAUSSDB(DWS)-MODIFY修改列

时间：2024-12-10 11:28:50

MODIFY修改列

MySQL使用MODIFY关键字修改列数据类型、设置非空约束。DSC工具迁移时会根据 GaussDB (DWS)的特性进行相应适配。

输入示例

     
          CREATE TABLE IF NOT EXISTS `runoob_alter_test`(
    `dataType0` varchar(100),
    `dataType1` bigint,
    `dataType2` bigint,
    `dataType3` bigint
)ENGINE=InnoDB DEFAULT CHARSET=utf8;

## A.
ALTER TABLE runoob_alter_test MODIFY dataType1 smallint;

## B.
ALTER TABLE runoob_alter_test MODIFY dataType1 smallint NOT NULL;

## C.
ALTER TABLE runoob_alter_test MODIFY dataType1 smallint NOT NULL FIRST;

## D.
ALTER TABLE runoob_alter_test MODIFY dataType1 smallint NOT NULL AFTER dataType3;

输出示例

     
          CREATE TABLE "public"."runoob_alter_test"
(
  "datatype0" VARCHAR(400),
  "datatype1" BIGINT,
  "datatype2" BIGINT,
  "datatype3" BIGINT
)
  WITH ( ORIENTATION = ROW, COMPRESSION = NO )
  NOCOMPRESS
  DISTRIBUTE BY HASH ("datatype0");

-- A.
ALTER TABLE "public"."runoob_alter_test" MODIFY "datatype1" SMALLINT NULL DEFAULT NULL;

-- B.
ALTER TABLE "public"."runoob_alter_test" MODIFY "datatype1" SMALLINT NOT NULL;

-- C.
ALTER TABLE "public"."runoob_alter_test" MODIFY "datatype1" SMALLINT NOT NULL;

-- D.
ALTER TABLE "public"."runoob_alter_test" MODIFY "datatype1" SMALLINT NOT NULL;