Question

我想编写一个以@FirmId为参数的存储过程，我将根据此参数使用相关表。

我想要获得的（但我不想使用）是这样的：

CREATE PROCEDURE spFirmDetailGetByFirmId 
    @FirmId AS INT
AS
BEGIN
    IF @FirmId = 1
        SELECT * FROM Firm1
    ELSE IF @FirmId = 2
        SELECT * FROM Firm2
        .
        .
        .
        .
    ELSE IF @FirmId = 1000
        SELECT * FROM Firm1000
END

而且我也不想创建查询字符串然后执行EXEC，就像在下面的代码块中那样。因为真正的查询过于复杂，如果我使用此选项将很难管理。

CREATE PROCEDURE spFirmDetailGetByFirmId 
    @FirmId AS INT
AS
BEGIN 
    DECLARE @Query AS NVARCHAR(MAX) = 'SELECT * FROM Firm'
    SET @Query = @Query + CAST(@FirmId AS NVARCHAR(10))
    EXEC(@Query)
END

还有其他选择吗？感谢。

Answer 1

我带你的是表格是相同的并且将保持相同以建议两种方法：

DECLARE @Firm VARCHAR(10)='Firm3';

SELECT * FROM Firm1 WHERE @Firm='Firm1'
UNION ALL
SELECT * FROM Firm2 WHERE @Firm='Firm2'
UNION ALL
SELECT * FROM Firm3 WHERE @Firm='Firm3'
[...]
UNION ALL
SELECT * FROM Firm1000 WHERE @Firm='Firm1000'

第二个是：

DECLARE @query NVARCHAR(MAX)='SELECT * FROM ####';
SET @query=REPLACE(@query,'####',@Firm);
EXEC (@query)

第二个可以与VIEW（代替@query）一起使用，您可以在其中将VIEW的定义读入变量并创建ALTER VIEW - 动态声明...你的程序将调用相同的VIEW（但这会因并行调用而崩溃！）

Answer 2

此代码可以通过在存储过程中使用来自动创建视图，每次需要添加列

declare @tableId  int
declare @columns varchar(max)
declare @tablesCount int
declare @tableName varchar(255)
declare @query varchar(255)
declare @id int
declare @result nvarchar(max)

set @columns = ''
set @tableName = 'Firm'
set @id = 1
set @result = ''

--Base table
select @tableId = object_id from sys.tables where name =@tableName
--Count how many table with the 'same name'
select @tablesCount= count(*) from sys.tables where name like @tableName+'%'
--Build Columns to add in the view
select  @columns =@columns+name+', 'from Sys.columns where object_id = @tableId

--Drop View
set @result = 'Drop view  vw_'+@tableName
exec sp_executesql @result
set @result=''

while(@id<=@tablesCount)
Begin 
 declare @idVarchar varchar(10)
 set @idVarchar = cast(@id as varchar(10))

 set @result =@result+'Select '+@columns+@idVarchar+' as FirmId from '+@tableName+@idVarchar
 +'
Union all
'
 set @id =@id+1
End
set @result  = substring(@result, 1, len(@result)-12)
set @result='Create view vw_'+@tableName+' as
'+@result


exec sp_executesql @result

还有另一种选择，你也可以使用sp_helpText来获取视图的当前定义，并仅追加添加新表标识符

根据参数返回不同表的存储过程

2 个答案: