The UPDATE statement allows you to update a single record or multiple records in a table.
The syntax for the UPDATE statement is:
SET column = expression
Example #1 – Simple example
Let’s take a look at a very simple example.
SET name = ‘HP’
WHERE name = ‘IBM’;
This statement would update all supplier names in the suppliers table from IBM to HP.
Example #2 – More complex example
You can also perform more complicated updates.
You may wish to update records in one table based on values in another table. Since you can’t list more than one table in the UPDATE statement, you can use the EXISTS clause.
SET supplier_name = ( SELECT customers.name
WHERE customers.customer_id = suppliers.supplier_id)
( SELECT customers.name
WHERE customers.customer_id = suppliers.supplier_id);Whenever a supplier_id matched a customer_id value, the supplier_name would be overwritten to the customer name from the customers table.