Modifies rows in a table.
UPDATE table-name[[AS] correlation-name] SET column-name = expression, ... [ WHERE search-condition ]
The table-name specifies the name of the table to update. Only a single table is allowed.
An identifier to use when referencing the table from elsewhere in the statement.
Each named column is set to the value of the expression on the right side of the equal sign. There are no restrictions on the expression. If the expression is a column-name, the old value is used.
Only columns specified in the SET clause have their values changed. In particular, you cannot use UPDATE to set a column's value to its default.
If a WHERE clause is specified, only rows satisfying search-condition are updated.
The UPDATE statement modifies values in a table.
Character strings inserted into tables are always stored in the same case as they are entered, regardless of whether the database is case sensitive.
The following statement transfers employee Philip Chin (employee 129) from the sales department to the marketing department (department 400).
UPDATE Employees SET DepartmentID = 400 WHERE EmployeeID = 129
An example using correlation-name.
UPDATE Employee E SET salary = salary * 1.05 WHERE EXISTS( SELECT 1 FROM Sales S HAVING E.Sales > Avg( S.sales) GROUP BY S.dept_no )