Updating data in tables

Updating data in a column

We have a students table. Let’s say we decide to increase marks of each student who is enrolled in the JavaScript course, by 5 marks each.

To do that, SQL provides an UPDATE TABLE statement, which can be used to update data in the columns in a table.

Note that after running the statement, for the students who are enrolled in JavaScript (Johnson and Tony), marks are increased by 5 each.

Observe that the UPDATE table statement can be broken down in three parts in the above example. The first is simply UPDATE followed by the name of the table (in this case, students). The second part actually updates the column value. It consists of the keyword SET followed by an expression, where the field to the left of = is updated with the result of expression at the other side. The last part is the conditional expression in WHERE clause, which filters out the rows for which the data has to updated.