About SQL Conditions

Conditions can have several forms, as shown in the following syntax.

condition::=

Description of the illustration condition.gif

If you have installed Oracle Text, then you can create conditions with the built-in operators that are part of that product, including CONTAINS, CATSEARCH, and MATCHES. For more information on these Oracle Text elements, please refer to Oracle Text Reference.

If you are using Oracle Expression Filter, then you can create conditions with the built-in EVALUATE operator that is part of that product. For more information, please refer to Oracle Database Application Developer's Guide - Expression Filter.

The sections that follow describe the various forms of conditions. You must use appropriate condition syntax whenever condition appears in SQL statements.

You can use a condition in the WHERE clause of these statements:

• DELETE

• SELECT

• UPDATE

You can use a condition in any of these clauses of the SELECT statement:

• WHERE

• START WITH

• CONNECT BY

• HAVING

A condition could be said to be of a logical datatype, although Oracle Database does not formally support such a datatype.

The following simple condition always evaluates to TRUE:

1 = 1 

The following more complex condition adds the salary value to the commission_pct value (substituting the value 0 for null) and determines whether the sum is greater than the number constant 25000:

NVL(salary, 0) + NVL(salary + (salary*commission_pct, 0) > 25000)

Logical conditions can combine multiple conditions into a single condition. For example, you can use the AND condition to combine two conditions:

(1 = 1) AND (5 < 7) 

Here are some valid conditions:

name = 'SMITH' 
employees.department_id = departments.department_id 
hire_date > '01-JAN-88' 
job_id IN ('SA_MAN', 'SA_REP') 
salary BETWEEN 5000 AND 10000
commission_pct IS NULL AND salary = 2100