SQL Server 向临时表插入数据示例

编程学习 2021-07-05 13:42www.dzhlxh.cn编程入门
SQL Server 向临时表插入数据,用临时表和表变量代替游标会极大的提高性能,狼蚁网站SEO优化有个示例,大家可以参考下
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。
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。

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