[英]Count unique values in table column - result is always 1
我想知道是否有人可以發現我在哪里出問題了? 我想返回一列的唯一值的數量。 當我在Phpmyadmin上運行此查詢時,結果是正確的,但是當我嘗試通過PHP進行操作時,我一直得到結果1。
//Find out number of unique slotids and assign to variable
$q2= "SELECT COUNT( DISTINCT(`slotid`) ) FROM `individualavailability`";
$result2 = mysqli_query ($dbcon, $q2);
$count = mysqli_num_rows ($result2);
echo $count. " slot ids";
mysqli_num_rows函數返回從服務器讀取的行數,而不是查詢所計數的slotid數。 這樣的事情應該更好地工作:
$q2= "SELECT COUNT( DISTINCT(`slotid`) ) as cnt FROM `individualavailability`";
$r2 = mysqli_query ($dbcon, $q2);
$row = mysqli_fetch_assoc($r2);
echo $row["cnt"];
$query=("SELECT count(DISTINCT (`slotid`)) as total from `individualavailability`");
$result=mysqli_query ($dbcon, $query);
$row=mysqli_fetch_assoc($result);
echo $row['total'];
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