SQL WHERE: Difference between revisions
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=Overview= | =Overview= | ||
The <code>WHERE</code> clause is the mechanism for filtering out unwanted data from the [[SQL#Result_Set|result set]]. The <code>WHERE</code> clause can be used with <code>[[SQL_SELECT#WHERE|SELECT]]</code>, <code>[[SQL_UPDATE#Overview|UPDATE]]</code> and <code>[[SQL_DELETE#Overview|DELETE]]</code>, but not with <code>[[SQL_INSERT#Overview|INSERT]]</code>. | The <code>WHERE</code> clause is the mechanism for filtering out unwanted data from the [[SQL#Result_Set|result set]]. The <code>WHERE</code> clause can be used with <code>[[SQL_SELECT#WHERE|SELECT]]</code>, <code>[[SQL_UPDATE#Overview|UPDATE]]</code> and <code>[[SQL_DELETE#Overview|DELETE]]</code>, but not with <code>[[SQL_INSERT#Overview|INSERT]]</code>. The <code>WHERE</code> clause may contain an arbitrary number of filter conditions separated by <code>AND</code>, <code>OR</code> and <code>NOT</code> operators, and optionally grouped together with parentheses. | ||
<font size=-1.5> | |||
<font color=green><b>FROM</b></font> <filter_condition> <font color=green><b>AND</b></font>|<font color=green><b>OR</b></font> <filter_condition> ... | |||
</font> | |||
<syntaxhighlight lang='sql'> | <syntaxhighlight lang='sql'> | ||
SELECT * FROM person WHERE person.name = 'Alice' AND (person.eye_color = 'blue' OR person.eye_color = 'black'); | SELECT * FROM person WHERE person.name = 'Alice' AND (person.eye_color = 'blue' OR person.eye_color = 'black'); | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=Filter Conditions= | =Filter Conditions= | ||
==<tt>NULL</tt> in Conditions== | ==<tt>NULL</tt> in Conditions== | ||
Also see: {{Internal|SQL#SQL_NULL|<tt>NULL</tt>}} | Also see: {{Internal|SQL#SQL_NULL|<tt>NULL</tt>}} | ||
Revision as of 22:06, 23 May 2024
Internal
Overview
The WHERE clause is the mechanism for filtering out unwanted data from the result set. The WHERE clause can be used with SELECT, UPDATE and DELETE, but not with INSERT. The WHERE clause may contain an arbitrary number of filter conditions separated by AND, OR and NOT operators, and optionally grouped together with parentheses.
FROM <filter_condition> AND|OR <filter_condition> ...
SELECT * FROM person WHERE person.name = 'Alice' AND (person.eye_color = 'blue' OR person.eye_color = 'black');
Filter Conditions
NULL in Conditions
Also see: