SQL SERVER 优化实例：从运行30分钟到运行只要30秒

核心提示：以下的SQL语句在服务器需要运行长达30分钟才能完成:SELECT dbo.ComFlow.ComFlowCode, dbo.ComFlow.ComCode,dbo.ComFlow.CustCode, dbo.ComFlow.DepartCode, dbo.ComFlow.SaleCode,dbo.ComFlow.Em

以下的SQL语句在服务器需要运行长达30分钟才能完成:

SELECT　　 dbo.ComFlow.ComFlowCode, dbo.ComFlow.ComCode,
dbo.ComFlow.CustCode, dbo.ComFlow.DepartCode, dbo.ComFlow.SaleCode,
　　　　　　　　　　　dbo.ComFlow.EmpCode, dbo.ComFlow.Quantity *
dbo.Commodity.ConvertRate AS Quantity, CONVERT(datetime, DATENAME(yyyy,
　　　　　　　　　　　dbo.ComFlow.FlowDate) + '-' + DATENAME(mm, dbo.ComFlow.
FlowDate) + '-' + DATENAME(dd, dbo.ComFlow.FlowDate)) AS FlowDate,
　　　　　　　　　　　dbo.ComFlow.SalType, dbo.Employee.DepartCode AS
DepartIn, dbo.Sale.DepartCode AS DepartOut,
　　　　　　　　　　　dbo.ComFlow.Quantity * dbo.Commodity.TradePrice *
dbo.Commodity.Discount / 100 AS Total, dbo.Department.GrpCode AS GrpCodeIn,
　　　　　　　　　　　Department1.GrpCode AS GrpCodeOut
FROM　　　　 dbo.ComFlow INNER JOIN
　　　　　　　　　　　dbo.Customer ON
　　　　　　　　dbo.ComFlow.SalType IN (N'促销', N'流向退货', N'多级流向')
AND dbo.ComFlow.CustCode = dbo.Customer.CustCode
　　　　　　　　Or ComFlow_1.SalType IN (N'自然流向', N'自然流向退货')
AND ComFlow_1.OutCustCode = Customer_1.CustCode
　　　　　　INNER JOIN
　　　　　　　　　　　dbo.CustomerRelation ON dbo.ComFlow.ComCode =
dbo.CustomerRelation.ComCode AND
　　　　　　　　　　　dbo.CustomerRelation.CustCode = dbo.Customer.CustCode
INNER JOIN
　　　　　　　　　　　dbo.Employee ON dbo.CustomerRelation.EmpCode =
dbo.Employee.
EmpCode INNER JOIN
　　　　　　　　　　　dbo.Sale ON dbo.ComFlow.SaleCode = dbo.Sale.SaleCode
INNER JOIN
　　　　　　　　　　　dbo.Department ON dbo.Department.DepartCode = dbo.Employee.DepartCode INNER JOIN
　　　　　　　　　　　dbo.Department AS Department1 ON Department1.DepartCode
= dbo.Sale.DepartCode AND
　　　　　　　　　　　dbo.Department.GrpCode <> Department1.GrpCode INNER JOIN
　　　　　　　　　　　dbo.Commodity ON dbo.ComFlow.ComCode = dbo.Commodity.ComCode
WHERE　　
(NOT (dbo.ComFlow.SalType = N'流向退货')) OR
　　　　　　　　　　　(NOT (dbo.Customer.Type = N'医药公司'))