SQL查询使用UNION从SELECT COUNT语句对表求和

Question

我目前正在尝试总结一个MySQL语句的结果，该语句为我提供了几个不同表的行数。

我已经研究了与此有关的stackoverflow的每种解决方案。 不幸的是，我无法找出适合我的情况的正确语法。

我的工作陈述没有总结出来：

SET @shipmentId=456;
SELECT
        (SELECT COUNT(*) FROM Table1 WHERE ShipmentID = @shipmentId)
        UNION ALL
        (SELECT COUNT(*) FROM Table2 WHERE ShipmentID = @shipmentId)
        UNION ALL
        (SELECT COUNT(*) FROM Table3 WHERE ShipmentID = @shipmentId)
        UNION ALL
        (SELECT COUNT(*)FROM Table4 WHERE ShipmentID = @shipmentId)
        UNION ALL
        (SELECT COUNT(*)FROM Table5 WHERE ShipmentID = @shipmentId);

我认为这应该是最接近正确解决方案的方法，但是我不确定（尝试了很多变体）：

SET @shipmentId=456;
SELECT SUM(MeasuredValues) FROM
    SELECT(
        (SELECT COUNT(*) FROM Table1 WHERE ShipmentID = @shipmentId) AS MeasuredValues
        UNION ALL
        (SELECT COUNT(*) FROM Table2 WHERE ShipmentID = @shipmentId) AS MeasuredValues
        UNION ALL
        (SELECT COUNT(*) FROM Table3 WHERE ShipmentID = @shipmentId) AS MeasuredValues
        UNION ALL
        (SELECT COUNT(*)FROM Table4 WHERE ShipmentID = @shipmentId) AS MeasuredValues
        UNION ALL
        (SELECT COUNT(*)FROM Table5 WHERE ShipmentID = @shipmentId)  AS MeasuredValues) t1;    

在此先感谢您的帮助。

已经尝试了以下链接： StackOverFlow Solution1

StackOverFlow解决方案2

Answer 1

您可以简单地总结一下您的选择：

SET @shipmentId=456;
SELECT
  (SELECT COUNT(*) FROM Table1 WHERE ShipmentID = @shipmentId)
+
  (SELECT COUNT(*) FROM Table2 WHERE ShipmentID = @shipmentId)
+
  (SELECT COUNT(*) FROM Table3 WHERE ShipmentID = @shipmentId)
+
  (SELECT COUNT(*) FROM Table4 WHERE ShipmentID = @shipmentId)
+
  (SELECT COUNT(*) FROM Table5 WHERE ShipmentID = @shipmentId);