SELECT COUNT(*) AS count - 如何使用这个计数 [英] SELECT COUNT(*) AS count - How to use this count
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问题描述
而不是这样做:
$cars = $mysqli->query("SELECT * FROM cars");
$count = $cars->num_rows();
if ($count) {
// is rows
}
我不想选择所有行或单列,我只想要计数.
I want to not have to select all rows or a single column, I simply want the count.
在我的脑海中:
$cars = $mysqli->query("SELECT COUNT(*) as count FROM cars");
但是我该如何使用那个计数值呢?我需要对其运行 if 语句.
But then how do I use that count value? I need to run an if statement on it.
推荐答案
不建议在 SQL 中对名称使用保留字.所以我称计数结果为 cnt.由于您的函数是标量,即您只期望返回一个值,您可以使用:
It's not recommended to use reserved words for names in SQL. So I call the count result cnt instead. As your function is scalar, i.e. you expect only one value back, you can use:
$count = $mysqli->query("select count(*) as cnt from cars")->fetch_object()->cnt;
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