[英]How to set min(value) variable as 0 when no value is returned by the sql query
$sql = "SELECT min(id) as sid FROM table1 where ....";
$result = mysql_query($sql);
$row = mysql_fetch_array($result);
$sid = $row['sid'];
当sql查询没有返回任何值时,如何将$ sid设置为0
(这里table1中的id是int类型)
请帮我....
如果没有匹配的行,则min()函数将返回NULL值,因此使用coalesce
或ifnull()
将其转换为零:
SELECT coalesce(min(id), 0) AS sid ...
SELECT ifnull(min(id), 0) AS sid ...
尝试这个:
$num_rows = mysql_num_rows($result);
if($num_rows == 0)
{
$sid = 0;
}
mysql_num_rows返回查询的行数
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