Commands to modify data in sql

Use UPDATE and DELETE commands in SQL to modify data: UPDATE command updates existing records, the syntax is: UPDATE table_name SET column1 = value1, column2 = value2, ... WHERE condition;DELETE command deletes records, the syntax is: :DELETE FROM table_name WHERE condition; Be sure to use with caution because they are destructive operations. Use the WHERE clause to specify conditions to update or delete only specific rows.

Commands to modify data in SQL

Use the UPDATE and DELETE commands in SQL to change the data.

UPDATE Command

UPDATE command is used to update existing records in a table. The syntax is:

<code class="sql">UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;</code>

• table_name: The name of the table to be updated.
• column1, column2, ...: The column name to be updated.
• value1, value2, ...: The new value to be updated.
• condition: Specify the conditions for the rows to be updated. The default is to update all rows.

Example:

<code class="sql">UPDATE customers
SET name = 'John Doe', email = 'john.doe@example.com'
WHERE id = 12345;</code>

This query updates the record with customer ID 12345 to have the name "John Doe" and the email "john.doe@ example.com".

DELETE Command

DELETE command is used to delete records from a table. The syntax is:

<code class="sql">DELETE FROM table_name
WHERE condition;</code>

• table_name: The name of the table from which records are to be deleted.
• condition: Specify the conditions for rows to be deleted. The default is to delete all rows.

Example:

<code class="sql">DELETE FROM orders
WHERE order_date < '2021-01-01';</code>

This query will delete all orders with dates earlier than January 1, 2021.

Note

• Please use caution when using the UPDATE and DELETE commands as they are destructive operations.
• Always make sure to back up the database before performing operations that modify data.
• Use the WHERE clause to specify conditions to update or delete only specific rows.

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