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How to Alter Multiple Columns at Once in SQL Server?

  • Difficulty Level : Expert
  • Last Updated : 16 Nov, 2021

In SQL, sometimes we need to write a single query to update the values of all columns in a table. We will use the UPDATE keyword to achieve this. For this, we use a specific kind of query shown in the below demonstration. For this article, we will be using the Microsoft SQL Server as our database and Select keyword.

Step 1: Create a Database. For this use the below command to create a database named GeeksForGeeks.

Query:

CREATE DATABASE GeeksForGeeks

Output:

Step 2: Use the GeeksForGeeks database. For this use the below command.

Query:

USE GeeksForGeeks

Output:

Step 3: Create a table of FIRM inside the database GeeksForGeeks. This table has 4 columns namely FIRST_NAME, LAST_NAME, SALARY, and BONUS containing the first names, last names, salaries, and bonuses of the members in a firm.

Query:

CREATE TABLE FIRM(
FIRST_NAME VARCHAR(20),
LAST_NAME VARCHAR(20),
SALARY INT,
BONUS INT
);

Output:



Step 4: Describe the structure of the table FIRM.

Query:

EXEC SP_COLUMNS FIRM;

Output:

Step 5: Insert 5 rows into the FIRM table.

Query:

INSERT INTO FIRM VALUES('ALEX','STONE',10000,1000);
INSERT INTO FIRM VALUES('MATT','JONES',20000,2000);
INSERT INTO FIRM VALUES('JOHN','STARK',30000,3000);
INSERT INTO FIRM VALUES('GARY','SCOTT',40000,4000);
INSERT INTO FIRM VALUES('RICHARD','WALT',50000,5000);

Output:

Step 6: Display all the rows of the FIRM table.

Query:



SELECT * FROM FIRM;

Output:

Step 7: Alter multiple(2) columns of the table FIRM by adding 2 columns to the table simultaneously. The 2 columns are JOINING_DATE and LEAVING_DATE containing the date of joining of the member and the date of leaving of the member. Use the keyword ALTER and ADD to achieve this.

Syntax:

ALTER TABLE TABLE_NAME ADD COLUMN1 
DATA_TYPE, COLUMN2 DATA_TYPE........;

Query:

ALTER TABLE FIRM ADD JOINING_DATE DATE,
 LEAVING_DATE DATE;

Output:

Step 8: Describe the structure of the altered table FIRM.

Query:

EXEC SP_COLUMNS FIRM;

Note: The table description now has 2 extra columns.



Output:

Step 9: Update the table by inserting data into the 2 newly added columns of the FIRM table. Use keyword UPDATE.

Syntax:

UPDATE TABLE_NAME SET COLUMN1=VALUE,
COLUMN2=VALUE WHERE CONDITION;

Query:

UPDATE FIRM SET JOINING_DATE='01-JAN-2001',
LEAVING_DATE='01-JAN-2002' WHERE FIRST_NAME='ALEX';
UPDATE FIRM SET JOINING_DATE='02-FEB-2001',
LEAVING_DATE='02-FEB-2002' WHERE FIRST_NAME='MATT';
UPDATE FIRM SET JOINING_DATE='03-MAR-2001',
LEAVING_DATE='03-MAR-2002' WHERE FIRST_NAME='JOHN';
UPDATE FIRM SET JOINING_DATE='04-APR-2001',
LEAVING_DATE='04-APR-2002' WHERE FIRST_NAME='GARY';
UPDATE FIRM SET JOINING_DATE='05-MAY-2001',
LEAVING_DATE='05-MAY-2002' WHERE FIRST_NAME='RICHARD';

Output:

Step 10: Display all the rows of the altered FIRM table.

Query:

SELECT * FROM FIRM;

Note: The displayed table now has 2 extra columns.



Output:

Step 11: Alter multiple(2) columns of the table FIRM by dropping 2 columns from the table simultaneously. The 2 columns are JOINING_DATE and LEAVING_DATE containing the date of joining of the member and the date of leaving of the member. Use the keyword ALTER and DROP to achieve this.

Syntax:

ALTER TABLE TABLE_NAME DROP 
COLUMN COLUMN1, COLUMN2........;

Query:

ALTER TABLE FIRM DROP COLUMN
JOINING_DATE,LEAVING_DATE;

Output:

Step 12: Describe the structure of the altered table FIRM.

Query:

EXEC SP_COLUMNS FIRM;

Note: The table description now has 2 fewer columns.

Output:

Step 13: Display all the rows of the altered FIRM table.

Query:

SELECT * FROM FIRM;

Note: The displayed table now has 2 fewer columns.

Output:


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