Add column,constraint and modify datatype

Alter table statement

The ALTER TABLE statement is used to add, delete, or modify columns in an existing table and is also used to add and drop various constraints on an existing table

->Add column

Syntax:

ALTER TABLE table_name ADD column_name datatype;

->Add constraint

Syntax:

ALTER TABLE table_name add constraint constraint_name(column_name);

->MODIFY COLUMN

Syntax:

ALTER TABLE table_name MODIFY COLUMN column_name datatype;