SQL 异常：将数据类型 nvarchar 转换为 int 时出错

Question

看起来像是一个转换问题，但是当应用转换（我认为是正确的格式）时，我仍然得到 SQL在 Visual Studio Web Developer 2010 Express 中引发的异常（VB.NET)

从具有 1 个输入参数和 4 个输出参数的存储过程开始，相关代码片段如下所示：

ALTER PROCEDURE [dbo].[SelectCompanies] 

@tickersList NVARCHAR(max) = NULL,
@YearInWhichEarningsExistForAllComparisonCompanies int OUTPUT,
@topEndToStartYear nvarchar(9) OUTPUT,
@middleEndToStartYear nvarchar(9) OUTPUT,
@bottomEndToStartYear nvarchar(9) OUTPUT

AS
BEGIN

SET @YearInWhichEarningsExistForAllComparisonCompanies = (SELECT TOP 1 ey.[Year] FROM company c, earningspershare e, earningspershareYear ey WHERE c.ticker_id = e.ticker_id AND e.EarningsPerShareID = ey.EarningsPerShareID AND c.tickerSymbol IN (  SELECT * FROM dbo.fnCSVStringToTable(@tickersList,',')  ) AND ey.Value is not null ORDER by ey.[Year] DESC);

DECLARE @topStartYear int, @topEndYear int;
DECLARE @middleStartYear int, @middleEndYear int;
DECLARE @bottomStartYear int, @bottomEndYear int;


SET @topStartYear = @YearInWhichEarningsExistForAllComparisonCompanies;

SET @topEndYear = @topStartYear - 2;


SET @topEndToStartYear = CAST(@topEndYear As nvarchar(4)) + N'-'  ; --ERROR

....

相关VB.NET代码如下：

    Dim year As New SqlParameter
    Dim topEndToStartYear As New SqlParameter
    Dim middleEndToStartYear As New SqlParameter
    Dim bottomEndToStartYear As New SqlParameter


    'Add tables
    dadCompanies = New SqlDataAdapter("SelectCompanies", conn)
    dadCompanies.SelectCommand.CommandType = CommandType.StoredProcedure

    If Not IsNothing(tBx_c_tickerSymbol.Text.ToString) Then
        dadCompanies.SelectCommand.Parameters.AddWithValue("@tickersList", tBx_c_tickerSymbol.Text.ToString)

        'year Output Parameter
        year = dadCompanies.SelectCommand.Parameters.AddWithValue("@YearInWhichEarningsExistForAllComparisonCompanies", SqlDbType.Int)
        year.Size = 4
        year.Direction = ParameterDirection.Output

        'topEndToStartYear Output Parameter
        topEndToStartYear = dadCompanies.SelectCommand.Parameters.AddWithValue("@topEndToStartYear", SqlDbType.NVarChar)
        topEndToStartYear.Size = 10
        topEndToStartYear.Direction = ParameterDirection.Output

        'middleEndToStartYear Output Parameter
        middleEndToStartYear = dadCompanies.SelectCommand.Parameters.AddWithValue("@middleEndToStartYear", SqlDbType.NVarChar)
        middleEndToStartYear.Size = 12
        middleEndToStartYear.Direction = ParameterDirection.Output

        'bottomEndToStartYear Output Parameter
        bottomEndToStartYear = dadCompanies.SelectCommand.Parameters.AddWithValue("@bottomEndToStartYear", SqlDbType.NVarChar)
        bottomEndToStartYear.Size = 12
        bottomEndToStartYear.Direction = ParameterDirection.Output

    End If

    dadCompanies.Fill(dstCompanies, "company")
....

注意事项：

从 SQL Server Managment Studio 2012 中执行的存储过程执行良好，没有任何错误。
当使用 IISExpress .NET v2.0.50727 通过 Visual Studio Web Developer Express 2010 进行调试时，抛出 SQL 服务器异常。
将 SQL 服务器中的这一行 CAST(@topEndYear As nvarchar(4)) + N'-'（发生错误的地方）切换为 N'-' + CAST(@topEndYear As nvarchar( 4)) 纠正问题，即以 nvarchar 字符开头，然后转换
在 VB.NET 中将值 SqlDbType.NVarChar 更改为 SqlDbType.NVarChar.ToString 更正问题，如果我将问题行保留为 CAST(@topEndYear As nvarchar(4)) + N' -'

我真的很想了解为什么会这样。即使我有一些解决方案，他们也没有给我解释原因。我以为我对 Casting 掌握得很好，也许我遗漏了什么？

Answer 1

如果您使用 AddWithValue，则第二个参数是值，但您传递了 SqlDbType。而是使用 Add。这是反对AddWithValue的原因之一：

'year Output Parameter
Dim Year = dadCompanies.SelectCommand.Parameters.Add("@YearInWhichEarningsExistForAllComparisonCompanies", SqlDbType.Int)
Year.Size = 4
Year.Direction = ParameterDirection.Output

'topEndToStartYear Output Parameter
Dim topEndToStartYear = dadCompanies.SelectCommand.Parameters.Add("@topEndToStartYear", SqlDbType.NVarChar)
topEndToStartYear.Size = 10
topEndToStartYear.Direction = ParameterDirection.Output

'middleEndToStartYear Output Parameter
Dim middleEndToStartYear = dadCompanies.SelectCommand.Parameters.Add("@middleEndToStartYear", SqlDbType.NVarChar)
middleEndToStartYear.Size = 12
middleEndToStartYear.Direction = ParameterDirection.Output

'bottomEndToStartYear Output Parameter
Dim bottomEndToStartYear = dadCompanies.SelectCommand.Parameters.Add("@bottomEndToStartYear", SqlDbType.NVarChar)
bottomEndToStartYear.Size = 12
bottomEndToStartYear.Direction = ParameterDirection.Output

SQL 异常：将数据类型 nvarchar 转换为 int 时出错

SQL Exception: Error converting data type nvarchar to int

sql

vb.net

asp.net

casting

sql-server-2012-express