xxxxxxxxxx
ALTER TABLE Customers
ALTER COLUMN age VARCHAR(2);
xxxxxxxxxx
ALTER TABLE table_name
ALTER COLUMN column_name datatype;
-- Example
ALTER TABLE product
ALTER COLUMN description VARCHAR(250);
xxxxxxxxxx
ALTER TABLE table_name
ALTER COLUMN column_name new_data_type(size);
xxxxxxxxxx
#SQL Server
ALTER TABLE Customers
ALTER COLUMN age VARCHAR(2);
#MySQL
ALTER TABLE Customers
MODIFY COLUMN age VARCHAR(2);
#Oracle
ALTER TABLE Customers
MODIFY age VARCHAR(2);
#PostgreSQL
ALTER TABLE Customers
ALTER COLUMN age TYPE VARCHAR(2);
xxxxxxxxxx
ALTER TABLE employees
ALTER COLUMN last_name VARCHAR(75) NOT NULL;
xxxxxxxxxx
-- Change column type
ALTER TABLE table_name
ALTER COLUMN some_col VARCHAR(250);
-- Change column name
ALTER TABLE table_name
RENAME COLUMN old_column_name TO new_column_name;
-- Change column values
UPDATE table_name
SET col_name=LOWER(col_name);
-- Add column
ALTER TABLE table_name
ADD COLUMN new_col INTEGER;
-- DELETE column
ALTER TABLE table_name
DROP COLUMN col_name;
xxxxxxxxxx
ALTER TABLE table_name
ALTER COLUMN column_name column_type;