Check out example codes for "sql alter column size". It will help you in understanding the concepts better.

Code Example 1

ALTER TABLE table_name
ALTER COLUMN column_name datatype;

Code Example 2

ALTER TABLE table_name
ALTER COLUMN column_name datatype;
--ex.
ALTER TABLE Customers
ADD Email varchar(255);

Code Example 3

ALTER TABLE table_name
ALTER COLUMN column_name datatype;

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

Learn ReactJs, React Native from akashmittal.com