SQL;

ALTER TABLE IN SQL

Alter table is used to add, modify or delete coloumns in an existing table. It is also used to rename a table.
You can also set command drop and add various constraints on an existing table.

This command contain four sub command:

1. Alter add
2. Alter modify
3. Alter rename
4. Alter drop

ALTER TABLE To Add Column

ALTER TABLE table_name ADD 
(
column 1 datatype(size),
column 2 datatype(size),
column 3 datatype(size),

.........
);

ALTER TABLE To modify Column

 ALTER TABLE table_name MODIFY 
(
column 1 datatype(size),
column 2 datatype(size),
column 3 datatype(size),
.........
);
	

ALTER TABLE To RENAME Column

ALTER TABLE table_name RENAME COLUMN previous_column_name TO new_column_name;
	

ALTER TABLE To RENAME Column

ALTER TABLE table_name RENAME COLUMN previous_column_name TO new_column_name;
	

ALTER TABLE To DROP Column

ALTER TABLE table_name DROP column_name;