alter table query code example

Example 1: sql add column

ALTER TABLE Customers
ADD Email varchar(255);

Example 2: sql server alter column

ALTER TABLE table_name 
ALTER COLUMN column_name new_data_type(size);

Example 3: change data type in mysql

ALTER TABLE table_name

CHANGE COLUMN column_name column_name datatype;

Example 4: sql alter table

Adds, deletes or edits columns in a table. It can also be used to add and
delete constraints in a table, as per the above.
Example: Adds a new boolean column called ‘approved’ to a table named
‘deals’.
ALTER TABLE deals
ADD approved boolean;
Example 2: Deletes the ‘approved’ column from the ‘deals’ table
ALTER TABLE deals
DROP COLUMN approved;

Example 5: sql alter table

-- With check if field already exists

IF NOT EXISTS(SELECT 1 FROM sys.columns 
          WHERE Name = N'Email'
          AND Object_ID = Object_ID(N'dbo.Customers'))
BEGIN    
	ALTER TABLE Customers
    ADD Email varchar(255);
END