alter table set column 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: alter table modify column

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

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

Example 3: sql change column in existing table

'This adds 'NOT NULL' to excisting column counting in the table mytable'
ALTER TABLE mytable ALTER COLUMN counting INT NOT NULL;