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{{Refimprove|date=September 2014}}
A <code>WHERE</code> clause in [[SQL]] specifies that a SQL [[Data Manipulation Language|Data Manipulation Language (DML)]] statement should only affect rows that meet specified criteria. The criteria are expressed in the form of predicates. <code>WHERE</code> clauses are not mandatory clauses of SQL DML statements, but can be used to limit the number of rows affected by a SQL DML statement or returned by a query. In brief SQL WHERE clause is used to extract only those results from a SQL statement, such as: SELECT, INSERT, UPDATE, or DELETE statement.<ref>{{cite web|url=http://www.programmingunit.com/2014/01/30/sql-clause-things-beginners-must-know/|title=SQL WHERE Clause – Things beginners must know}}</ref>

==Overview==
<code>WHERE</code> is an [[SQL:ll2003|SQL]] reserved word.

The <code>WHERE</code> clause is used in conjunction with SQL DML statements, and takes the following general form:

<source lang="sql">
SQL-DML-Statement
FROM table_name 
WHERE predicate
</source>

all rows for which the predicate in the <code>WHERE</code> clause is True are affected (or returned) by the SQL DML statement or query. Rows for which the predicate evaluates to False or Unknown ([[Null (SQL)|NULL]]) are unaffected by the DML statement or query.

The following query returns only those rows from table ''mytable'' where the value in column ''mycol'' is greater than 100.

<source lang="sql">
SELECT *
FROM   mytable
WHERE  mycol > 100
</source>

The following [[Delete (SQL)|<code>DELETE</code> statement]] removes only those rows from table ''mytable'' where the column ''mycol'' is even ither NULL or has a value that is equal to 100.
<source lang="sql">
DELETE
FROM   mytable
WHERE  mycol IS NULL OR mycol = 100
</source>

== Predicates ==
(contracted; show full)<references />

== External links ==
* [http://www.psoug.org/reference/conditions.html PSOUG Home Puget Sound Oracle Users Group] gives several examples of SELECT statements with WHERE clauses.

{{SQL}}

[[Category:SQL keywords]]