PHP查询数据库中满足条件的记录数-php手册-php.cn

Home

php教程

php手册

PHP查询数据库中满足条件的记录数

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jun 06, 2016 pm 07:49 PM

phpdatabaseconditionInquiresatisfyusewebsiteRecordoutputneed

在需要输出网站用户注册数，或者插入数据之前判断是否有重复记录的时候，就需要获取满足条件的MySQL查询的记录数目。第一种方法：查询时候直接统计 123 $sql = "SELECT COUNT(*) AS count FROM TABLE WHERE id=' $id '" ; $result = mysql_fetch_array ( my

在需要输出网站用户注册数，或者插入数据之前判断是否有重复记录的时候，就需要获取满足条件的MySQL查询的记录数目。

第一种方法：查询时候直接统计

1
2
3

<span>$sql</span><span>=</span><span>"SELECT COUNT(*) AS count FROM TABLE WHERE id='<span>$id</span>'"</span><span>;</span>
<span>$result</span><span>=</span><span>mysql_fetch_array</span><span>(</span><span>mysql_query</span><span>(</span><span>$sql</span><span>)</span><span>)</span><span>;</span>
<span>$count</span><span>=</span><span>$result</span><span>[</span><span>'count'</span><span>]</span><span>;</span>

第二种方法：先取出，后统计

1
2
3

<span>$sql</span><span>=</span><span>"SELECT * FROM TABLE WHERE id='<span>$id</span>'"</span><span>;</span>
<span>$result</span><span>=</span><span>mysql_fetch_array</span><span>(</span><span>mysql_query</span><span>(</span><span>$sql</span><span>)</span><span>)</span><span>;</span>
<span>$count</span><span>=</span><span>count</span><span>(</span><span>$result</span><span>)</span><span>;</span><span>//或者$count=mysql_num_rows($result);</span>

不过直接使用MySQL的COUNT(*)在数据量庞大的时候，效率的优势是十分显著的，因为后者需要二次计算，所以还是最好使用前者进行数据条数的统计。

source url:http://www.benben.cc/blog/?p=345

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn