SQL ALTER TABLE

SQL ALTER TABLE

The ALTER TABLE statement is used to add, modify or delete columns in an existing table. It is also used to rename a table.

You can also use SQL ALTER TABLE command to add and drop various constraints on an existing table.

---

SQL ALTER TABLE Add Column

If you want to add columns in SQL table, the SQL alter table syntax is given below:

1. ALTER TABLE table_name ADD column_name column-definition;  

If you want to add multiple columns in table, the SQL table will be

1. ALTER TABLE table_name   
2. ADD (column_1 column-definition,  
3.            column_2 column-definition,  
4.            .....  
5.            column_n column-definition);  

---

SQL ALTER TABLE Modify Column

If you want to modify an existing column in SQL table, syntax is given below:

1. ALTER TABLE table_name MODIFY column_name column_type;  

If you want to modify multiple columns in table, the SQL table will be

1. ALTER TABLE table_name   
2. MODIFY (column_1 column_type,  
3.                   column_2 column_type,  
4.                  .....  
5.                   column_n column_type);  

---

SQL ALTER TABLE DROP Column

The syntax of alter table drop column is given below:

1. ALTER TABLE table_name DROP COLUMN column_name;  

---

SQL ALTER TABLE RENAME Column

The syntax of alter table rename column is given below:

1. ALTER TABLE table_name  
2. RENAME COLUMN old_name to new_name;