EN
MS SQL Server - Alter Table
0 points
In this article, we would like to show you how to modify a table in MS SQL Server.
Quick solution:
xxxxxxxxxx1
ALTER TABLE [table_name]2
ADD [column_name] DATA_TYPE;xxxxxxxxxx1
ALTER TABLE [table_name]2
ALTER COLUMN [column_name] DATA_TYPE;xxxxxxxxxx1
ALTER TABLE [table_name]2
DROP COLUMN [column_name];Note:
Go to the official documentation to see what you can use as
DATA_TYPE.
To show how the ALTER TABLE statement works, we will use the following table:
Note:
At the end of this article you can find database preparation SQL queries.
In this example, we will add email column to the users table.
Query:
xxxxxxxxxx1
ALTER TABLE [users]2
ADD [email] VARCHAR(255);Output (SELECT * FROM [users]):
In this example, we will delete the department_id column.
Query:
xxxxxxxxxx1
ALTER TABLE [users]2
DROP COLUMN [department_id];Output (SELECT * FROM [users]):
In this example, we will modify salary column datatype from DECIMAL to VARCHAR.
Query:
xxxxxxxxxx1
ALTER TABLE [users]2
ALTER COLUMN [salary] VARCHAR(255);Output:
create_tables.sql file:
xxxxxxxxxx1
CREATE TABLE [users] (2
[id] INT IDENTITY(1,1),3
[name] VARCHAR(50) NOT NULL,4
[surname] VARCHAR(50) NOT NULL,5
[department_id] INT,6
[salary] DECIMAL(15,2) NOT NULL,7
PRIMARY KEY ([id])8
);insert_data.sql file:
xxxxxxxxxx1
INSERT INTO [users]2
( [name], [surname], [department_id], [salary])3
VALUES4
('John', 'Stewart', 1, '3512.00'),5
('Chris', 'Brown', 2, '1344.00'),6
('Kate', 'Lewis', 3, '6574.00'),7
('Ailisa', 'Gomez', NULL, '6500.00'),8
('Gwendolyn', 'James', 2, '4200.00'),9
('Simon', 'Collins', 4, '3320.00'),10
('Taylor', 'Martin', 2, '1500.00'),11
('Andrew', 'Thompson', NULL, '2100.00');