Question

我在这里有一个关于SQL小提琴的工作示例： http://sqlfiddle.com/#!2/e75d6/34

使用以下查询：

SELECT *
FROM (Orders JOIN 
     Salesperson ON 
     Salesperson.ID = Orders.salesperson_id) 
      JOIN 
     (SELECT salesperson_id AS sid, MAX( Amount ) AS MaxOrder
      FROM Orders
      GROUP BY salesperson_id) AS TopOrderAmountsPerSalesperson
     ON (TopOrderAmountsPerSalesperson.sid=Orders.salesperson_id AND
         TopOrderAmountsPerSalesperson.MaxOrder=Orders.Amount)

但是当我尝试为第一个连接表分配别名时，如下所示：

SELECT *
FROM (Orders JOIN 
     Salesperson ON 
     Salesperson.ID = Orders.salesperson_id) AS SalesOrders
      JOIN 
     (SELECT salesperson_id AS sid, MAX( Amount ) AS MaxOrder
      FROM Orders
      GROUP BY salesperson_id) AS TopOrderAmountsPerSalesperson
     ON (TopOrderAmountsPerSalesperson.sid=SalesOrders.salesperson_id AND
         TopOrderAmountsPerSalesperson.MaxOrder=SalesOrders.Amount)

我收到语法错误。有什么想法吗？

我使用此SO作为别名连接表的资源： SQL Alias of joined tables

Answer 1

您可以为整个查询或表名或字段名提供别名，但不能在连接条件上提供别名。请尝试以下示例，并将Orders表的别名设为SalesOrders。

SELECT *
FROM Orders AS SalesOrders JOIN 
     Salesperson ON 
     Salesperson.ID = SalesOrders.salesperson_id 
      JOIN 
     (SELECT salesperson_id AS sid, MAX( Amount ) AS MaxOrder
      FROM Orders
      GROUP BY salesperson_id) AS TopOrderAmountsPerSalesperson
     ON (TopOrderAmountsPerSalesperson.sid=SalesOrders.salesperson_id AND
         TopOrderAmountsPerSalesperson.MaxOrder=SalesOrders.Amount)

检查SQL Fiddle

MySQL：连接表的别名 - 故障排除

1 个答案: