SQL Server 向临时表插入数据示例

复制代码 代码如下:
INSERT INTO #DirtyOldWIPBOM SELECT TOP (100) PERCENT dbo.WIP_BOM.Model, dbo.WIP_BOM.PartNumber,WIP_BOM.WIP
FROM dbo.WIP_BOM left OUTER JOIN dbo.BOM_CHINA ON LTRIM(dbo.WIP_BOM.Model) = LTRIM(dbo.BOM_CHINA.Model) AND LTRIM(dbo.WIP_BOM.PartNumber) = LTRIM(dbo.BOM_CHINA.PartNumber) AND dbo.WIP_BOM.Qty = dbo.BOM_CHINA.Qty AND BOM_CHINA.WIP=
WIP_BOM.WIP WHERE (dbo.BOM_CHINA.Model IS NULL) AND EXISTS(SELECT * FROM dbo.BOM_CHINA WHERE WIP = WIP_BOM.WIP AND LTRIM(Model) = LTRIM(WIP_BOM.Model))

这样就可以成功。
复制代码 代码如下:
但SELECT TOP (100) PERCENT dbo.WIP_BOM.Model, dbo.WIP_BOM.PartNumber,WIP_BOM.WIP into #DirtyOldWIPBOM
FROM dbo.WIP_BOM left OUTER JOIN dbo.BOM_CHINA ON LTRIM(dbo.WIP_BOM.Model) = LTRIM(dbo.BOM_CHINA.Model) AND LTRIM(dbo.WIP_BOM.PartNumber) = LTRIM(dbo.BOM_CHINA.PartNumber) AND dbo.WIP_BOM.Qty = dbo.BOM_CHINA.Qty AND BOM_CHINA.WIP=
WIP_BOM.WIP WHERE (dbo.BOM_CHINA.Model IS NULL) AND EXISTS(SELECT * FROM dbo.BOM_CHINA WHERE WIP = WIP_BOM.WIP AND LTRIM(Model) = LTRIM(WIP_BOM.Model))

会提示error "There is already an object named '#DirtyOldWIPBOM' in the database"

为什么？

[笔记]:千万不要用游标，用临时表和表变量代替游标会极大的提高性能，今天用游标处理700行数据用了2小时，用临时表不到1秒就搞定。