PHP mysqli查询以检查是否存在行

问题描述：

我有一个mysql表，我想检查是否存在一行，其中columnA = $ a和$ columnB = $ b.我不需要从那里选择任何东西.什么是有效的查询呢?目前，我正在这样做，

I have a mysql table, I want to check if a row exists where columnA=$a and $columnB=$b. I dont need to select anything from there. What should be efficient query for that? Currently Im doing like,

if ($stmt = mysqli->prepare("SELECT * FROM TABLE WHERE columnA=? && columnB= ? LIMIT 1")) {
    $stmt->bind_param("ss", $a, $b);
    $stmt->execute();
    $stmt->store_result();
    $count=$stmt->num_rows;
    $stmt->close();
    }
    return ($count > 0 ? true : false);

答

尝试一下:

if ($stmt = $mysqli->prepare("SELECT COUNT(*) FROM TABLE WHERE columnA=? && columnB=?")) {
    $stmt->bind_param("ss", $a, $b);
    $stmt->execute();
    $stmt->bind_result($count);
    $stmt->fetch();
    $stmt->close();
}

return ($count > 0 ? true : false);

现在您应该可以完成它

PHP mysqli查询以检查是否存在行

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