Difference between revisions of "COUNT()"
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==Purpose== | ==Purpose== | ||
Returns the number of rows in a SELECT statement query | Returns the number of rows in a SELECT statement query | ||
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==Syntax== | ==Syntax== | ||
COUNT(* | [DISTINCT] <expr>) | COUNT(* | [DISTINCT] <expr>) | ||
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==See Also== | ==See Also== | ||
[[SQL Aggregate Functions|AGGREGATES]], [[AVG()]], [[SQL MAX()|MAX()]], [[SQL MIN()|MIN()]], [[SQL SELECT|SELECT]], [[SUM()]] | [[SQL Aggregate Functions|AGGREGATES]], [[AVG()]], [[SQL MAX()|MAX()]], [[SQL MIN()|MIN()]], [[SQL SELECT|SELECT]], [[SUM()]] | ||
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==Description== | ==Description== | ||
Returns the number of rows in the query. If you specify DISTINCT, then only the rows which are unique in <expr> are counted. Specifying <expr> on its own returns the number of rows from the query for which <expr> is not NULL. If you specify the asterisk (*), then all rows are counted. | Returns the number of rows in the query. If you specify DISTINCT, then only the rows which are unique in <expr> are counted. Specifying <expr> on its own returns the number of rows from the query for which <expr> is not NULL. If you specify the asterisk (*), then all rows are counted. | ||
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==Example== | ==Example== | ||
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[[Category:Documentation]] | [[Category:Documentation]] | ||
[[Category:SQL]] | [[Category:SQL]] | ||
[[Category:Functions]] | [[Category:Functions]] | ||
[[Category:SQL Functions]] | [[Category:SQL Functions]] | ||
Latest revision as of 07:49, 7 December 2012
Contents
Purpose
Returns the number of rows in a SELECT statement query
Syntax
COUNT(* | [DISTINCT] <expr>)
See Also
AGGREGATES, AVG(), MAX(), MIN(), SELECT, SUM()
Description
Returns the number of rows in the query. If you specify DISTINCT, then only the rows which are unique in <expr> are counted. Specifying <expr> on its own returns the number of rows from the query for which <expr> is not NULL. If you specify the asterisk (*), then all rows are counted.
Example
// Get a count of all rows in the accounts table. SELECT COUNT(*) Total FROM accounts // Get a count of jobs SELECT COUNT(jobs) Jobs FROM employee // Get a count of distinct rows for jobs SELECT COUNT(DISTINCT jobs) Jobs FROM employee
