Tài liệu PL/SQL User’s Guide and Reference phần 10

This clause assigns the value of sql_expression to the column identified by
column_name. If sql_expression contains references to columns in the table
being updated, the references are resolved in the context of the current row. The old
column values are used on the right side of the equal sign.
In the following example, you increase every employee’s salary by 10%. The
original value of the sal column is multiplied by 1.10, then the result is assigned
to the sal column overwriting the original value.