c# - OleDbCommand 参数顺序和优先级

Question

过去 40 分钟我一直在调试这个查询，问题显然是参数的顺序。

SELECT * FROM tblSomeThing WHERE id = @id AND debut = @dtDebut AND fin = @dtFin

然后我以这种方式添加参数，注意最后两个参数被调换了，我没有得到任何结果。

cmd.Parameters.Add("@id", OleDbType.Integer).Value = idSociete;
cmd.Parameters.Add("@dtFin", OleDbType.Date).Value = dateTraitementFin;
cmd.Parameters.Add("@dtDebut", OleDbType.Date).Value = dateTraitementDebut;

当我按照它们在查询中出现的方式声明参数时，一切正常。

我认为首先要解决这个问题的是命名参数!我在这里错过了什么？

谢谢

Answer 1

根据 http://msdn.microsoft.com/en-us/library/system.data.oledb.oledbcommand.parameters.aspx OleDbCommand 不支持命名参数

The OLE DB .NET Provider does not support named parameters for passing parameters to an SQL statement or a stored procedure called by an OleDbCommand when CommandType is set to Text. In this case, the question mark (?) placeholder must be used. For example:

SELECT * FROM Customers WHERE CustomerID = ?

Therefore, the order in which OleDbParameter objects are added to the OleDbParameterCollection must directly correspond to the position of the question mark placeholder for the parameter in the command text.

所以参数的顺序很重要。