update type of column in sql code example

Example 1: sql change column types

ALTER TABLE table_name
ALTER COLUMN column_name datatype;

-- Example
ALTER TABLE product
ALTER COLUMN description VARCHAR(250);

Example 2: sqlserver add column to table

ALTER TABLE dbo.doc_exa 
ADD column_b VARCHAR(20) NULL, 
	column_c INT NULL ;

Example 3: alter table modify column

-- ORACLE 18c
ALTER TABLE table_name 
MODIFY column_name datatype;

-- Example
ALTER TABLE product
MODIFY description VARCHAR2(500 char);