How to use the MySQL update select statement?

In MySQL, you can update data in a table using the UPDATE SELECT statement. The syntax is as follows:

Update the table name by setting a column name to the value from another table where a certain condition is met.

The table name refers to the name of the table where data needs to be updated, column name 1 is the name of the column to be updated, column name 2 is the name of the column to be selected from another table, table name 2 is the name of the table from which columns will be selected, and the condition is used to filter the rows to be updated.

For instance, let’s say there are two tables, one is the orders table and the other is the customers table. The orders table has a column customer_id which stores the corresponding customer ID, while the customers table has two columns customer_id and customer_name, storing customer ID and customer name respectively.

To update the customer_name column in the orders table based on the customer_id in the orders table, you can use the following statement:

Update the orders to set the customer name by selecting the customer name from customers where the customer ID in orders matches the customer ID in customers, only where the customer name is currently null.

This statement will search for the corresponding customer_name in the customers table based on the customer_id in the orders table, and update it in the customer_name column of the orders table. It will only update the rows where customer_name is empty.

Please ensure that the subquery in the UPDATE SELECT statement only returns one row of results to avoid errors.