UPDATE

UPDATE

Purpose

Use the UPDATE statement to change existing values in a table or in the base table of a view or the master table of a materialized view.

Additional Topics

• Prerequisites

• Syntax

• Semantics

• Examples

Prerequisites

For you to update values in a table, the table must be in your own schema or you must have the UPDATE object privilege on the table.

For you to update values in the base table of a view:

• You must have the UPDATE object privilege on the view, and

• Whoever owns the schema containing the view must have the UPDATE object privilege on the base table.

The UPDATE ANY TABLE system privilege also allows you to update values in any table or in the base table of any view.

You must also have the SELECT object privilege on the object you want to update if:

• The object is on a remote database or

• The SQL92_SECURITY initialization parameter is set to TRUE and the UPDATE operation references table columns, such as the columns in a where_clause.

Syntax

update::=

Description of the illustration update.gif

(DML_table_expression_clause::=, update_set_clause ::=, where_clause ::=, returning_clause::=, error_logging_clause::=)

DML_table_expression_clause::=

Description of the illustration DML_table_expression_clause.gif

(subquery::=--part of SELECT, subquery_restriction_clause ::=, table_collection_expression ::=)

subquery_restriction_clause ::=

Description of the illustration subquery_restriction_clause.gif

table_collection_expression ::=

Description of the illustration table_collection_expression.gif

update_set_clause ::=

Description of the illustration update_set_clause.gif

where_clause ::=

Description of the illustration where_clause.gif

returning_clause::=

Description of the illustration returning_clause.gif

error_logging_clause::=

Updating a Table: Examples The following statement gives null commissions to all employees with the job SH_CLERK:

UPDATE employees
   SET commission_pct = NULL
   WHERE job_id = 'SH_CLERK';

The following statement promotes Douglas Grant to manager of Department 20 with a $1,000 raise:

UPDATE employees SET 
    job_id = 'SA_MAN', salary = salary + 1000, department_id = 120 
    WHERE first_name||' '||last_name = 'Douglas Grant'; 

The following statement increases the salary of an employee in the employees table on the remote database:

UPDATE employees@remote
   SET salary = salary*1.1
   WHERE last_name = 'Baer';

The next example shows the following syntactic constructs of the UPDATE statement:

• Both forms of the update_set_clause together in a single statement

• A correlated subquery

• A where_clause to limit the updated rows

UPDATE employees a 
    SET department_id = 
        (SELECT department_id 
            FROM departments 
            WHERE location_id = '2100'), 
        (salary, commission_pct) = 
        (SELECT 1.1*AVG(salary), 1.5*AVG(commission_pct) 
          FROM employees b 
          WHERE a.department_id = b.department_id) 
    WHERE department_id IN 
        (SELECT department_id 
          FROM departments
          WHERE location_id = 2900 
              OR location_id = 2700); 

The preceding UPDATE statement performs the following operations:

• Updates only those employees who work in Geneva or Munich (locations 2900 and 2700)

• Sets department_id for these employees to the department_id corresponding to Bombay (location_id 2100)

• Sets each employee's salary to 1.1 times the average salary of their department

• Sets each employee's commission to 1.5 times the average commission of their department

Updating a Partition: Example The following example updates values in a single partition of the sales table:

UPDATE sales PARTITION (sales_q1_1999) s
   SET s.promo_id = 494
   WHERE amount_sold > 1000;

Updating an Object Table: Example The following statement creates two object tables, people_demo1 and people_demo2, of the people_typ object created inTable Collections: Examples. The example shows how to update a row of people_demo1 by selecting a row from people_demo2:

CREATE TABLE people_demo1 OF people_typ;

CREATE TABLE people_demo2 OF people_typ;

UPDATE people_demo1 p SET VALUE(p) =
   (SELECT VALUE(q) FROM people_demo2 q
    WHERE p.department_id = q.department_id)
   WHERE p.department_id = 10;

The example uses the VALUE object reference function in both the SET clause and the subquery.

Correlated Update: Example For an example that uses a correlated subquery to update nested table rows, please refer to "Table Collections: Examples".

Using the RETURNING Clause During UPDATE: Example The following example returns values from the updated row and stores the result in PL/SQL variables bnd1, bnd2, bnd3:

UPDATE employees
  SET job_id ='SA_MAN', salary = salary + 1000, department_id = 140
  WHERE last_name = 'Jones'
  RETURNING salary*0.25, last_name, department_id
    INTO :bnd1, :bnd2, :bnd3;

The following example shows that you can specify a single-set aggregate function in the expression of the returning clause:

UPDATE employees
   SET salary = salary * 1.1
   WHERE department_id = 100
   RETURNING SUM(salary) INTO :bnd1;

90. View the Exhibit and examine the descriptions of the DEPT and LOCATIONS
tables.You want to update the CITY column of the DEPT table for all the rows
with the corresponding value in the CITY column of the LOCATIONS table for
each department.Which SQL statement would you execute to accomplish the task?
A. UPDATE dept d SET city = ANY (SELECT city FROM locations l);
B. UPDATE dept d SET city = (SELECT city FROM locations l)
WHERE d.location_id = l.location_id;
C. UPDATE dept d SET city = (SELECT city FROM locations l WHERE d.location_id
= l.location_id);
D. UPDATE dept d SET city = ALL (SELECT city FROM locations l
WHERE d.location_id = l.location_id);

Answer: C