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MySQL在两行之间差异,PHP神话sql_num_rows功能?
原标题:MySQL difference of two rows between two with PHP mysql_num_rows function?

能否在一定程度上缩小一个表的两行之间的差别?

我试图这样做,但努力工作:

$diff = mysql_num_rows("
SELECT (`used`-`paid`) 
FROM `coupons_codes` 
WHERE `cid`= ".$data[ cid ]." ");       
问题回答

你应该这样做:

//store the query in a string
$query = "SELECT `used`-`paid` FROM `coupons_codes` WHERE `cid`= ".$data[ cid ]." ";
//execute the query on the MySQL database
$result = mysql_query($query);
//extract the result from the response from the MySQL server
$diff = mysql_result($result, 0, 0);

您重新使用的功能用于计算从<条码>米sql_query(>);)查询中获取的分行数。

我建议你努力阅读有关公共卫生和社会福利部和我SQL的一些基本内容,我感到,你缺乏一些基本知识,无法真正制定良好的守则。





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