What is ALTER command with example?

Question

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

What is ALTER command explain with example?

The ALTER command is a DDL command to modify the structure of existing tables in the database by adding, modifying, renaming, or dropping columns and constraints. You can add columns, rename columns, delete columns, or change the data type of columns using the ALTER command.

Where is ALTER command used?

alter command is used for altering the table structure, such as,1to add a column to existing table.2to rename any existing column.3to change datatype of any column or to modify its size.4to drop a column from the table.

What is the difference between ALTER and update command explain with example?

This command initializes the value of all the tuples as NULL. This command sets fixed values in a tuple. Through this command, we can perform modifications to the table structure. UPDATE command is used to modify the data in the table.

Why ALTER is used?

ALTER TABLE is used to add, delete/drop or modify columns in the existing table. It is also used to add and drop various constraints on the existing table. ADD is used to add columns into the existing table.

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