Question

我遇到以下查询的问题，该查询应该计算数据库中的Null和Not Empty记录。我需要使用预准备语句来执行。我有以下代码，但我无法得到正确的输出。任何帮助将不胜感激！

$query = "SELECT UserName, COUNT(NULLIF(TRIM(UserName), ''))
FROM    Employee";
    $stmt = $db->prepare($query7);
    $stmt->execute();
    $stmt->store_result();
    $numrows = $stmt->num_rows;
    $stmt->bind_result($Count);
    for ($i=0; $i <$numrows; $i++) {
        $stmt->fetch();

        echo "Count: $Count";
    };

Answer 1

To count non-null and non-empty records, you can do:

SELECT COUNT(*)
FROM Employee
WHERE UserName IS NOT NULL AND UserName != ''

You don't need to use TRIM(UserName), because trailing spaces are ignored when comparing strings.

The full PHP code should be like this:

$query = "SELECT COUNT(*)
            FROM Employee
            WHERE UserName IS NOT NULL AND UserName != ''";
$stmt = $db->prepare($query);
$stmt->execute();
$stmt->store_result();
$stmt->bind_result($Count);
$stmt->fetch();
echo "Count: $Count";

PHP MySQL查询选择计数

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