What is the Difference Between Update and Alter?

The main difference between the UPDATE and ALTER commands in SQL lies in their purposes and what they modify. Here are the key differences:

ALTER Command:

1. It is a Data Definition Language (DDL) statement.
2. It operates on the structure level, not the data level.
3. It is used to add, delete, or modify the attributes of the tables in a database, such as adding or dropping columns.
4. By default, it initializes the values of all tuples as NULL.

UPDATE Command:

1. It is a Data Manipulation Language (DML) statement.
2. It operates on the data level.
3. It is used to update existing records in a database, modifying the values of the records in the relations.
4. It sets specified values in a tuple using the UPDATE command.

In summary, the ALTER command is used to modify the structure of a table, while the UPDATE command is used to modify the data within the table.

Comparative Table: Update vs Alter

The main difference between the UPDATE and ALTER commands in SQL lies in their function: ALTER is used to modify the structure of a table, while UPDATE is used to modify the data within the table. Here is a comparison table highlighting their differences:

For example, the ALTER command can be used to add a new column to a table, while the UPDATE command can be used to modify the values within that new column for specific rows.