The UPDATE Operation

As we saw in the overview, UPDATE modifies data in one or more columns in a table. Just like the INSERT operation, the UPDATE operation can also only be performed against a single table using a single statement. In most situations, you will filter out the records you would like to update and update only them. This filtration is done using a WHERE clause in the SELECT statement. The UPDATE statement also contains a SET clause, which defines what needs to be modified within the table, along with the values.

In our demo, we'll update a table called email. You can set one column or more during an UPDATE operation. If you want to update multiple columns, separate the column names with a comma.

The database engine looks for the column that is specified in the statement and updates all the rows in it. If you would like to update only a certain row or a certain set of rows, you would use the WHERE clause. This way, you can identify only those intersections of...