我收到此类型错误：条件表达式中的数据类型不匹配

Question

I use C# to insert data into access, and got this type of error. I don't think it is a type error.

My codes are as follows:

        OleDbConnection oleDbConn = new OleDbConnection();
        oleDbConn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\fgao16\Dropbox\lab\website\mydatabase.mdb;User Id=admin;Password=;";
        oleDbConn.Open();
        string creattable = "create table mytable2([ID] char(50),[Radiologist Name] char(50),[Interesting Cases Folder] char(50),[Procedure] char(50),[Ordering Physician] char(50),[Procedure Date] char(50),[Indications] char(50),[FieFindings] varchar(255),primary key([ID]))";
        OleDbCommand oComm = new OleDbCommand(creattable, oleDbConn);
        oComm.ExecuteNonQuery();

        //string strInsertString = "INSERT INTO Table1 (ID,fCollumn2) VALUES (@strCollumn1,@fCollumn2)";
        string strInsertString = "INSERT INTO Table1 ([ID],[Radiologist Name],[Interesting Cases Folder],[Procedure],[Ordering Physician],[Procedure Date],[Indications],[FieFindings]) VALUES (@ID,@Radiologist_Name,@Interesting_Cases_Folder,@Procedure,@Ordering_Physician,@Procedure_Date,@Indications,@Findings)";
        oComm = new OleDbCommand(strInsertString, oleDbConn);
        oComm.Parameters.Add("@ID", OleDbType.Char,50);
        oComm.Parameters["@ID"].Value = a;

        oComm.Parameters.Add("@Radiologist_Name", OleDbType.Char,50);
        oComm.Parameters["@Radiologist_Name"].Value = b;

        oComm.Parameters.Add("@Interesting_Cases_Folder", OleDbType.Char,50);
        oComm.Parameters["@Interesting_Cases_Folder"].Value = c;

        oComm.Parameters.Add("@Procedure", OleDbType.Char,50);
        oComm.Parameters["@Procedure"].Value = d;

        oComm.Parameters.Add("@Ordering_Physician", OleDbType.Char,50);
        oComm.Parameters["@Ordering_Physician"].Value = e;

        oComm.Parameters.Add("@Procedure_Date", OleDbType.Char,50);
        oComm.Parameters["@Procedure_Date"].Value = f;

        oComm.Parameters.Add("@Indications", OleDbType.Char,50);
        oComm.Parameters["@Indications"].Value = g;

        oComm.Parameters.Add("@Findings", OleDbType.VarChar,255);
        oComm.Parameters["@Findings"].Value = h;


        //@ID,@Radiologist_Name ,@,@    ,@,@,   @   ,@
       // string strInsertString = "INSERT INTO Table1 ([ID],[Radiologist Name],[Interesting Cases Folder],[Procedure],[Ordering Physician],[Procedure Date],[Indications],[FieFindings]) VALUES ('8','7','6','5','4','3','2','1')";

        oComm.ExecuteNonQuery();
        oleDbConn.Close();

Answer 1

Problem : The Exception Data type mismatch in criteria expression comes when there is a mismatch in DataType that is Expected and provided.

in your query your ID seems to be an Integer type. but you are providing the value as Char Type.

Solution : you need to provide the Integer parameters with OleDbType.Integer as parameter type.

Replace This :

oComm.Parameters.Add("@ID", OleDbType.Char,50);
        oComm.Parameters["@ID"].Value = a;

With This:

oComm.Parameters.Add("@ID", OleDbType.Integer);
        oComm.Parameters["@ID"].Value = a;