存儲過程中的字符串長

Question

我正在編寫此存儲過程，但不斷收到錯誤。

我的方法：

USE AllCtuStudentInfo 
GO 

SET ANSI_NULLS ON 
GO 
SET QUOTED_IDENTIFIER ON 
GO 

CREATE PROCEDURE SelectProcedure4 

    @myVar VARCHAR(8000), 
    @Schema varchar(50), 
    @ID int 
    --@ix INT = 1 


AS 
--WHILE @ix < 1000 
BEGIN 
    set @myVar = 'SELECT '+@Schema+'.Student.Name, '+@Schema+'.Student.Surname, '+@Schema+'.Course.Name AS Course,'+@Schema+'.LearningUnit.Name AS [Learning Unit], '+@Schema+'.Formative.[Formative Name], '+@Schema+'.FormativeMark.Mark, '+@Schema+'.Summative.[Summative Name], '+@Schema+'.SummativeMark.Mark AS Mark FROM '+@Schema+'.LearningUnit INNER JOIN '+@Schema+'.Formative INNER JOIN '+@Schema+'.Course INNER JOIN '+@Schema+'.SummativeMark INNER JOIN '+@Schema+'.FormativeMark INNER JOIN '+@Schema+'.Student ON '+@Schema+'.FormativeMark.FK_Student = '+@Schema+'.Student.ID ON '+@Schema+'.SummativeMark.FK_Student = '+@Schema+'.Student.ID ON '+@Schema+'.Course.ID = '+@Schema+'.Student.FK_Course INNER JOIN '+@Schema+'.Summative ON '+@Schema+'.SummativeMark.FK_Summative = '+@Schema+'.Summative.ID ON '+@Schema+'.Formative.ID = '+@Schema+'.FormativeMark.FK_Formative ON '+@Schema+'.LearningUnit.ID = '+@Schema+'.Summative.FK_LU AND '+@Schema+'.LearningUnit.ID = '+@Schema+'.Formative.FK_LU WHERE '+@Schema+'.Student.ID = '''+CAST(@ID AS VARCHAR(10))+''';' 
    --SET @ix = @ix + 1 
    EXEC @myVar 
END 

我如何執行它：

USE AllCtuStudentInfo 

EXEC SelectProcedure4 @myVar = '', @Schema = 'Auckland_Park', @ID = 1 

錯誤：

Msg 203, Level 16, State 2, Procedure SelectProcedure4, Line 15

The name 'SELECT Auckland_Park.Student.Name, Auckland_Park.Student.Surname, Auckland_Park.Course.Name AS Course,Auckland_Park.LearningUnit.Name AS [Learning Unit], Auckland_Park.Formative.[Formative Name], Auckland_Park.FormativeMark.Mark, Auckland_Park.Summative.[Summative Name], Auckland_Park.SummativeMark.Mark AS Mark FROM Auckland_Park.LearningUnit INNER JOIN Auckland_Park.Formative INNER JOIN Auckland_Park.Course INNER JOIN Auckland_Park.SummativeMark INNER JOIN Auckland_Park.FormativeMark INNER JOIN Auckland_Park.Student ON Auckland_Park.FormativeMark.FK_Student = Auckland_Park.Student.ID ON Auckland_Park.SummativeMark.FK_Student = Auckland' is not a valid identifier.

正如你可以看到它被切斷。我嘗試了其他一些方法，但我總是以相同的錯誤結束，並在同一個地方被截斷。

請幫忙！

Answer 1

下面是一個使用sp_executesql和參數化查詢的示例。

CREATE PROCEDURE dbo.SelectProcedure4 

    @myVar nvarchar(MAX), 
    @Schema sysname, 
    @ID int 
AS 
DECLARE @SchemaName nvarchar(130) = QUOTENAME(@Schema); 

SET @myVar = 'SELECT '+@SchemaName+'.Student.Name, '+@SchemaName+'.Student.Surname, '+@SchemaName+'.Course.Name AS Course,'+@SchemaName+'.LearningUnit.Name AS [Learning Unit], '+@SchemaName+'.Formative.[Formative Name], '+@SchemaName+'.FormativeMark.Mark, '+@SchemaName+'.Summative.[Summative Name], '+@SchemaName+'.SummativeMark.Mark AS Mark FROM '+@SchemaName+'.LearningUnit INNER JOIN '+@SchemaName+'.Formative INNER JOIN '+@SchemaName+'.Course INNER JOIN '+@SchemaName+'.SummativeMark INNER JOIN '+@SchemaName+'.FormativeMark INNER JOIN '+@SchemaName+'.Student ON '+@SchemaName+'.FormativeMark.FK_Student = '+@SchemaName+'.Student.ID ON '+@SchemaName+'.SummativeMark.FK_Student = '+@SchemaName+'.Student.ID ON '+@SchemaName+'.Course.ID = '+@SchemaName+'.Student.FK_Course INNER JOIN '+@SchemaName+'.Summative ON '+@SchemaName+'.SummativeMark.FK_Summative = '+@SchemaName+'.Summative.ID ON '+@SchemaName+'.Formative.ID = '+@SchemaName+'.FormativeMark.FK_Formative ON '+@SchemaName+'.LearningUnit.ID = '+@SchemaName+'.Summative.FK_LU AND '+@SchemaName+'.LearningUnit.ID = '+@SchemaName+'.Formative.FK_LU WHERE '+@SchemaName+'.Student.ID = @ID;' 

EXECUTE sp_executesql @myVar, N'@ID int', @ID= @ID; 
GO