我試圖使用連接來獲取3個不同表中的某些列。我做了一個視覺表示,展示了我的SQL語句中表連接的方式。我希望通過role_level
表中的rl.level_priority
來排序結果。通過SQL排序左連接另一個左連接
FROM users u LEFT JOIN
user_roles ur
ON u.id = ur.user_id LEFT JOIN
role_level rl
ON ur.role_level_id = rl.id AND ur.role_id = ?
WHERE (u.id = ?) AND (u.group_id <= ?) AND (u.db_isdeleted is null)
GROUP BY u.id, u.fullname, u.image_thumb, u.group_id
ORDER BY rl.level_priority
我很努力地看看我是否正確地做到了這一點。我得到的結果,但他們沒有在rl.level_priority
整個代碼的問候排序上升是在這裏:
while($stmt_two->fetch()){
// HIGHEST USER ROLE DISPLAYED - ACTIVE (6), LESS ACTIVE(7), PASSIVE (9)
$db_user_group_id = 7;
// DISPLAY USERS WITH A SET JOB POSITION
$sql_three = <<< EOF
SELECT u.id, u.fullname, u.image_thumb, u.group_id, MIN(rl.level_priority)
FROM users u LEFT JOIN
user_roles ur
ON u.id = ur.user_id LEFT JOIN
role_level rl
ON ur.role_level_id = rl.id AND ur.role_id = ?
WHERE (u.id = ?) AND (u.group_id <= ?) AND (u.db_isdeleted is null)
GROUP BY u.id, u.fullname, u.image_thumb, u.group_id
ORDER BY rl.level_priority;
EOF;
$stmt_three = $mysqli->prepare($sql_three) or die ("Feil i database<br>" . $sql . "<br><b>Feilmelding:</b> " . $mysqli->error);
$stmt_three->bind_param("iii",$db_user_role_id, $db_user_group_id, $db_role_id);
$stmt_three->execute();
$stmt_three->store_result();
$stmt_three->bind_result($db_id_role, $db_fullname_role, $db_image_thumb_role, $db_group_id, $db_level_priority);
$results_users_role = $stmt_three->num_rows;
$results += $results_users_role;
if (!$results_users_role == 0) {
while($stmt_three->fetch()) {
$body_html .= "<tr>";
if (!empty($db_image_thumb_role)) {
$body_html .= "<td><img src=\"data:image/jpeg;base64," . base64_encode($db_image_thumb_role) . "\"/></td>\n";
}
else {
$body_html .= "<td><img src=\"img/anonymous-user-thumb.png\"></td>";
}
$body_html .= "<td><a href=user.php?u=" . $db_id_role . ">" . $db_fullname_role . "</a></td></tr>";
}
}
$stmt_three->close();
}
移動ur.role_id條件JOIN的行爲。 (現在它作爲內部連接執行...) – jarlh
選擇你正在分組的BY的MIN並不會有很大的意義。 – Strawberry
爲什麼MIN(rl.level_priority)與GROUP BY rl.level_priority結合?這與你想要做的事情相反。一般的GROUP BY規則說:如果指定了GROUP BY子句,SELECT列表中的每個列引用必須標識一個分組列或者是一個set函數的參數。 – jarlh