Answers for "column type change in sql"

sql change column types

ALTER TABLE table_name
ALTER COLUMN column_name datatype;

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

sql server alter column

ALTER TABLE table_name 
ALTER COLUMN column_name new_data_type(size);

sqlserver add column to table

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