Question

请有人帮我解决这个问题;

所以我得到了这个SQL查询;

SELECT Route.Number FROM ROUTE INNER JOIN Operator ON Operator.Name =
Route.Operatedby INNER JOIN Operator ON Operator.Name = Route.OperatorName 
WHERE Operator.Description = "Fawcal";

这是我得到的错误;

Not Unique table/alias

Answer 1

您要加入同一张桌子两次，请使用Alias

SELECT r.Number 
FROM 
    ROUTE  r INNER JOIN Operator o 
        ON o.Name = r.Operatedby  
    INNER JOIN Operator o2 
        ON o2.Name = r.OperatorName 
WHERE o.Description = "Fawcal";

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