sql alter column

1ALTER TABLE table_name
2ALTER COLUMN column_name datatype;
3
4-- Example
5ALTER TABLE product
6ALTER COLUMN description VARCHAR(250);

1ALTER TABLE table_name 
2ALTER COLUMN column_name new_data_type(size);
3

1ALTER TABLE nom_table
2RENAME COLUMN colonne_ancien_nom TO colonne_nouveau_nom

1ALTER TABLE table_name
2
3CHANGE COLUMN column_name column_name datatype; 

1Changes the data type of a table’s column.
2Example: In the ‘users’ table, make the column ‘incept_date’ into a
3‘datetime’ type.
4ALTER TABLE users
5ALTER COLUMN incept_date datetime;

1-- With check if field already exists
2
3IF NOT EXISTS(SELECT 1 FROM sys.columns 
4          WHERE Name = N'Email'
5          AND Object_ID = Object_ID(N'dbo.Customers'))
6BEGIN    
7	ALTER TABLE Customers
8    ADD Email varchar(255);
9END