Help Center> GaussDB(DWS)> Tool Guide> DSC> SQL Syntax Migration Reference> MySQL Syntax Migrating> Schema Objects and Data Definition Language (DDL)> Table (Optional Parameters and Operations)> Adding/Deleting a Column
Updated on 2024-04-28 GMT+08:00
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Adding/Deleting a Column

The statements for adding and deleting columns in MySQL are different from those in GaussDB(DWS). DSC will perform adaptation based on GaussDB(DWS) features during migration.

GaussDB does not support the update of sequence numbers in table definitions. Temporarily, Migration Tool does not support the complete migration of the <cf id="Bold">FRIST</cf> and <cf id="Bold">AFTER</cf> features. So as a workaround, it simply deletes the keyword.

Input

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CREATE TABLE IF NOT EXISTS `runoob_alter_test`(
    `dataType1` int NOT NULL AUTO_INCREMENT,
    `dataType2` FLOAT(10,2),
    `dataType3` DOUBLE(20,8),
    `dataType4` TEXT NOT NULL,
    `dataType5` YEAR NOT NULL DEFAULT '2018',
    `dataType6` DATETIME NOT NULL DEFAULT '2018-10-12 15:27:33.999999',
    `dataType7` CHAR NOT NULL DEFAULT '',
    `dataType8` VARCHAR(50),
    `dataType9` VARCHAR(50) NOT NULL DEFAULT '',
    `dataType10` TIME NOT NULL DEFAULT '10:20:59',
    PRIMARY KEY(`dataType1`)
)ENGINE=InnoDB DEFAULT CHARSET=utf8;

## A.
ALTER TABLE runoob_alter_test ADD dataType1_1 INT NOT NULL AFTER dataType1;
ALTER TABLE runoob_alter_test DROP dataType1_1;

## B.
ALTER TABLE runoob_alter_test ADD dataType1_1 INT NOT NULL FIRST;
ALTER TABLE runoob_alter_test DROP dataType1_1;

## C.
ALTER TABLE runoob_alter_test ADD COLUMN dataType1_1 INT NOT NULL AFTER dataType2;
ALTER TABLE runoob_alter_test DROP COLUMN dataType1_1;

## D.
ALTER TABLE runoob_alter_test ADD COLUMN dataType1_1 INT NOT NULL FIRST;
ALTER TABLE runoob_alter_test DROP COLUMN dataType1_1;

## E.
ALTER TABLE runoob_alter_test ADD COLUMN(dataType1_1 INT NOT NULL, dataType1_2 VARCHAR(200) NOT NULL);
ALTER TABLE runoob_alter_test DROP COLUMN dataType1_1, DROP COLUMN dataType1_2;

Output

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CREATE TABLE "public"."runoob_alter_test"
(
  "datatype1" SERIAL NOT NULL,
  "datatype2" REAL,
  "datatype3" DOUBLE PRECISION,
  "datatype4" TEXT NOT NULL,
  "datatype5" SMALLINT NOT NULL DEFAULT '2018',
  "datatype6" TIMESTAMP WITHOUT TIME ZONE NOT NULL DEFAULT '2018-10-12 15:27:33.999999',
  "datatype7" CHAR(4) NOT NULL DEFAULT '',
  "datatype8" VARCHAR(200),
  "datatype9" VARCHAR(200) NOT NULL DEFAULT '',
  "datatype10" TIME WITHOUT TIME ZONE NOT NULL DEFAULT '10:20:59',
  PRIMARY KEY ("datatype1")
)
  WITH ( ORIENTATION = ROW, COMPRESSION = NO )
  NOCOMPRESS
  DISTRIBUTE BY HASH ("datatype1");

-- A.
ALTER TABLE "public"."runoob_alter_test" ADD COLUMN "datatype1_1" INTEGER NOT NULL DEFAULT 0;
ALTER TABLE "public"."runoob_alter_test" DROP COLUMN "datatype1_1" RESTRICT;

-- B.
ALTER TABLE "public"."runoob_alter_test" ADD COLUMN "datatype1_1" INTEGER NOT NULL DEFAULT 0;
ALTER TABLE "public"."runoob_alter_test" DROP COLUMN "datatype1_1" RESTRICT;

-- C.
ALTER TABLE "public"."runoob_alter_test" ADD COLUMN "datatype1_1" INTEGER NOT NULL DEFAULT 0;
ALTER TABLE "public"."runoob_alter_test" DROP COLUMN "datatype1_1" RESTRICT;

-- D.
ALTER TABLE "public"."runoob_alter_test" ADD COLUMN "datatype1_1" INTEGER NOT NULL DEFAULT 0;
ALTER TABLE "public"."runoob_alter_test" DROP COLUMN "datatype1_1" RESTRICT;

-- E.
ALTER TABLE "public"."runoob_alter_test" ADD COLUMN "datatype1_1" INTEGER NOT NULL, ADD COLUMN "datatype1_2" VARCHAR(800) NOT NULL DEFAULT '';
ALTER TABLE "public"."runoob_alter_test" DROP COLUMN "datatype1_1" RESTRICT, DROP COLUMN "datatype1_2" RESTRICT;