While the INSERT statement adds new rows to a table, the UPDATE statement changes existing rows. Use it to change values in single rows, groups of rows, or all the rows in a table.
The UPDATE statement specifies the row or rows you want to change and the new data. The new data can be a constant or expression that you specify, or it can be data pulled from other tables.
Here's a simplified version of the UPDATE syntax for updating specified rows with an expression:
UPDATE table_name SET column_name = expression [WHERE search_conditions]
The UPDATE keyword is followed by the name of a table or view. As in all the data modification statements, you can change the data in only one ...