What is ALTER Command?
In SQL, the ALTER command is preferred to rectify, edit or update the attributes of the table. ALTER command is a Data Definition Language command.
Syntax :
To add a column to the existing table
ALTER TABLE tableName
ADD columnName columnDefinition;
What is UPDATE Command?
In SQL, the UPDATE command is used to influence the data of a column. This is a Data Manipulation Language command, so it cannot modify the definition of the table.
Syntax :
For table name that we want to update
UPDATE tableName
For which columns have to update
SET column1 = value1, column2 = value2, …,columnN=valueN.
For which row you have to update
WHERE condition
Important: The where clause is mandatory here. Else whole data will get updated.
Difference between ALTER and UPDATE Command in SQL
| S.No | ALTER Command | UPDATE Command |
| 1 | It is a Data Definition Language (DDL). | It is a Data Manipulation Language (DML). |
| 2 | This command operates on the structure level. | This command performs on the data level. |
| 3 | This command is used to add, remove, and change the details of the tables in a database. | It is used to update the details of a table. |
| 4 | This command initializes the value of all the tuples as NULL. | This command sets fixed values in a tuple. |
| 5 | Through this command, we can perform modifications to the table structure. | UPDATE command is used to modify the data in the table. |
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