使用带有 SQL 游标的 while 循环？

Question

我正在创建一个 sql 脚本，我有 2 个游标来循环数据，一个表游标和一个公司游标。 我在使用 while 循环将数据复制到架构中将公司光标放在一起时遇到问题 我需要使用 If 语句回答以下问题

该表是否有 companyID 列？检查公司 ID 的 if 语句 如果是，则根据光标中的 companyID 复制数据

我声明了一个@firstLoop

这是我的光标特定代码

DECLARE @firstLoop BIT
SET @firstLoop = true

----------- Cursor specific code starts here ------------
-- company cursor
declare copyCompanyDataCursor CURSOR fast_forward FOR
SELECT ID from #CompanyIDs;

open copyCompanyDataCursor
fetch next from copyCompanyDataCursor into @Company_Id;

WHILE @@FETCH_STATUS = 0
    BEGIN

        declare @processorder int;
        declare @tablename varchar(500);
        -- table cursor

        declare copyTableDataCursor CURSOR fast_forward FOR
        SELECT processorder,tablename from #TableList4 order by processorder;

        open copyTableDataCursor
        fetch next from copyTableDataCursor into @processorder, @tablename;

        while @@FETCH_STATUS = 0
        BEGIN
            SET IDENTITY_INSERT [c365online_script1.dbo.tCompany] OFF

            -- Does the table have a companyID column? if statement checking for company id

            -- if yes then copy data based on companyID in cursor

            -- if no check if this is the first time through company loop and copy all data
            -- if @firstloop company exists look at information schema

                    -- insert into c365online_script1.dbo.tCompany(selec
                    EXEC('INSERT ' + @Destination_Database_Name + '.dbo.' + @tablename + ' SELECT * FROM ' + @Source_Database_Name + '.dbo.' + @tablename + ')')

                    -- company logic


            SET IDENTITY_INSERT [c365online_script1.dbo.tCompany] ON

            FETCH NEXT FROM copyTableDataCursor into @processorder,@tablename;
        END

        close copyTableDataCursor;
        Deallocate copyTableDataCursor;

--INSERT INTO c365online_script1.dbo.tCompany
--SELECT *
--FROM production2.tCompany
--WHERE ISNULL(CompanyID, 0) = 0  -- copy all data where id is equal to zero
--@Destination_Database_Name

--      
        --EXEC(INSERT  + @Destination_Database_Name + '.dbo.' + @tablename + ' SELECT * FROM ' + @Source_Database_Name + '.dbo.' + @tablename + ' WHERE ' + @Source_Database_Name + '.dbo.' + @tablename + '.CompanyID = ' + @Company_Id + ')'      
        SET @firstLoop = false;
        FETCH NEXT FROM copyCompanyDataCursor into @Company_Id;
    END
CLOSE copyCompanyDataCursor;
DEALLOCATE copyCompanyDataCursor;

Answer 1

我建议你将两个 CURSORS 都替换为 while 循环。

SQL Server 中的 CURSORS 成本性能非常糟糕，而不是用带有 While 循环的临时表替换它们肯定会提高性能，并且您必须编写更简单的编码类型。

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