MySQL不允許我刪除記錄

Question

我正在嘗試從PHP執行此MySQL子句

$conn = new mysqli($servername, $username, $password, $dbname);

$sql = "DELETE FROM table_2 WHERE id in (select DISTINCT(id) FROM table_2 WHERE id NOT IN (SELECT id FROM table_2 WHERE p = 1 AND r =1))";

if ($conn->query($sql) === TRUE) {
    echo "Record deleted successfully";
} else {
    echo "Error deleting record: " . $conn->error;
}

我收到以下錯誤

刪除記錄時出錯：您無法在FROM子句中指定目標表“ table_2”進行更新

我究竟做錯了什么？

Answer 1

您可以使用子查詢來繞過MySQL的這一限制，但是您的語句可以像這樣簡化：

DELETE FROM table_2 
WHERE id NOT IN (
  SELECT id FROM (
    SELECT id FROM table_2 WHERE p = 1 AND r = 1
  ) t
)