In my VS2013, when I assign a value to SqlParameter with ADO, the generated SQL statement is the default when I assign null.

/// <summary>        ///add a piece of data/// </summary>         Public BOOLAdd (model.wechatdocuments Model) {StringBuilder strSQL=NewStringBuilder (); Strsql.append ("INSERT INTO wechatdocuments ("); Strsql.append ("Documentname,documentpath,documentformattype,uploadby,uploaddate,uploaderopenid,billno,billamount, Reviewedby,revieweddate,reviewedresult,reviewedcomment)"); Strsql.append ("VALUES ("); Strsql.append ("@DocumentName, @DocumentPath, @DocumentFormatType, @UploadBy, @UploadDate, @UploaderOpenId, @BillNo, @BillAmount , @Reviewedby, @ReviewedDate, @ReviewedResult, @ReviewedComment)"); sqlparameter[] Parameters= {                    NewSqlParameter ("@DocumentName", SqlDbType.VarChar, -),                    NewSqlParameter ("@DocumentPath", SqlDbType.VarChar, -),                    NewSqlParameter ("@DocumentFormatType", SqlDbType.VarChar, -),                    NewSqlParameter ("@UploadBy", SqlDbType.VarChar, -),                    NewSqlParameter ("@UploadDate", Sqldbtype.datetime),NewSqlParameter ("@UploaderOpenId", SqlDbType.VarChar, -),                    NewSqlParameter ("@BillNo", SqlDbType.VarChar, -),                    NewSqlParameter ("@BillAmount", Sqldbtype.float,8),                    NewSqlParameter ("@Reviewedby", SqlDbType.VarChar, -),                    NewSqlParameter ("@ReviewedDate", Sqldbtype.datetime),NewSqlParameter ("@ReviewedResult", Sqldbtype.bit,1),                    NewSqlParameter ("@ReviewedComment", SqlDbType.VarChar, -)}; parameters[0]. Value =model.            DocumentName; parameters[1]. Value =model.            Documentpath; parameters[  2]. Value = model.            documentFormatType; parameters[3]. Value = model. Uploadby??""; parameters[4]. Value = model. Uploaddate?? Convert.todatetime ("1970/01/01"); parameters[5]. Value = model. Uploaderopenid??""; parameters[6]. Value = model. Billno??""; parameters[7]. Value = model. Billamount??0; parameters[8]. Value = model. Reviewedby??""; parameters[9]. Value = model. Revieweddate?? Convert.todatetime ("1970/01/01"); parameters[Ten]. Value =model.            Reviewedresult; parameters[ One]. Value = model. Reviewedcomment??""; returnSqlserverhelper.excutenonquery (strsql.tostring (), CommandType.Text, parameters); }

EXEC sp_executesql N ' insert into wechatdocuments (documentname,documentpath,documentformattype,uploadby,uploaddate, Uploaderopenid,billno,billamount,reviewedby,revieweddate,reviewedresult,reviewedcomment) VALUES (@DocumentName, @ Documentpath, @DocumentFormatType, @UploadBy, @UploadDate, @UploaderOpenId, @BillNo, @BillAmount, @Reviewedby, @ Revieweddate, @ReviewedResult, @ReviewedComment) ', N ' @DocumentName varchar ($), @DocumentPath varchar (500), @ documentFormatType varchar, @UploadBy varchar, @UploadDate datetime, @UploaderOpenId varchar, @BillNo varchar, @BillAmount float, @Reviewedby varchar, @ReviewedDate datetime, @ReviewedResult bit,@ Reviewedcomment varchar (+) ', @DocumentName = ' 20151216072318_2511.jpg ', @DocumentPath = '/uploadfiles/bill/ 20151216072318_2511.jpg ',@DocumentFormatType =default, @UploadBy = ', @UploadDate = ' 2015-12-16 07:23:29.107 ', @UploaderOpenId = ', @BillNo = ', @BillAmount =0, @Reviewedby = ', @ReviewedDate = ' 1970-01-01 00:00:00 ', @ReviewedResult =0, @ReviewedComment = '

Execution Error:

MSG 8178, Level A, State 1, line 0
The parameterized query ' (@DocumentName varchar, @DocumentPath varchar, @Document ' expects the parameter ' @ documentFormatType ', which was not supplied.

Change the @documentformattype=default to @documentformattype=null and execute it successfully. When adding a new piece of data, some fields need to be null, do not know if it is me vs.

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Error the type ' string ' must is a non-nullable value type in order to use it as parameter ' T ' in the generic type or me Thod ' system.nullable<t>

The error 19 character type must be a non-null value type to use as a system for the generic type or method of the parameter T. Air <T>

In my VS2013, when I assign a value to SqlParameter with ADO, the generated SQL statement is the default when I assign null.