Initialising Pbject Properties And Value Types To DBNull.Value
Aug 21, 2007
Hi,
I have a ShoppingCart class with a lot of properties (due to structure of a legacy Orders table). I have a ShoppingCart table also which contains a lot of the same fields as my orders table.
There are a lot of fields (mostly ints) which have been initalised to 0
in my ShoppingCart class and then inserted into the ShoppingCart table
when users add items to the cart.
These fields are then inserted into the orders table upon check out.
When i attempt to place a new record in the orders table from the ShoppingCart table, I am receiving a bunch of Foregin Key constraint errors due to all the int fields containing 0's.
What i would like to do is initalise all the properites of my ShoppingCart object to DBNull.Value but of course I can't convert type 'System.DBNull' to 'int' and i can't set to 'null' either as int's are value types.
I also tried:
private Int32 _fieldname = Convert.ToInt32(DBNull.Value);
This compiled but gave InvalidCastException runtime error.
So the only option that i can think of is, as i build the parameter array to be sent to my stored procedure, test the value of each parameter, if it is 0 (or an empty string) then don't pass the actual field value but pass DBNull.Value instead.
I REALLY don't want to do this as there are around 60 parameters being passed to this procedure and this will be time consuming and messy.
Any suggestions would be most appreciated!
ps If i could avoid having 60 parameters being passed I would...trust me!
I want restore database in my disk , but i cant . I've click and add from device. this is the screen. And when i click content , it show me this text :Â Object cannot be cast from DBNull to other types. (mscorlib) .Â
i need to initialise the backup devices as the the backup files have grown so big thats its occupy hard drive space , each device is for @ day for all databse we use , what do i do
I've been writing this stuff for a while, and can't seem to come to the conclusion of how I should be retrieving data and assigning this data to variables.
Since i'm using SQL Server, I'm convinced that I should be using the datareaders GetSqlDouble (or whatever) function, but this would mean i need my local variables to be one of the SQL types. The problem with that is, that there will have to be lots of conversions done by me to be able to use a SQL type in my application.
For instance, I have a class where i'm retrieving dates. In order to retrieve them correctly (Null values included), I need to retrieve them with GetSqlDateTime(), then when it comes time to display the date in a table, i must first check for nulls, then convert to a string. This seems to be very cumbersome. Would I be better off just using GetDateTime(), and the .ToString method, and ignoring Sql Types all together?
so, basically, how are you guys using your sql server data? with the supplied sql types, and doing all of the post-processing work manually? I feel like i'm having trouble conveying my issue...hopefully someone knows what i mean....i'd just like some direction to save trouble in the long run, since i feel like there's got to be a better way...
As a part of migration to .net we are redesigning sql server 7 database and moving it to sql server 2005. There are a lot of fields with dbnull value in the existing db. It would be nice to populate them with some default value while transfering data to the new datbase on sql server 2005. What is the best way to deal with the issue, are there any possible drawbacks and problems. Your input will be greatly appreciated.
Hello! Is there an easy way to deal with this situation below when reading in data from a SQL Database: int? myNullableColumn;myNullableColumn = Convert.ToInt32(datarow["datacolumn"]);
Where, ideally, 'myNullableColumn' would be 'null' if the value was 'DBNull.Value'. This does not work because Convert.ToInt32 will not convert 'DBNull.Value to null', but instead throws an error. Is there a built in funtion that does do this? Thanks!
Hi I have only been coding in .Net for about six months, and am not sure if this is a C# problem or an SQL one. I use the Data Access Application Block in my program.
I have two optional fields on my form (RangeFrom and RangeTo). If the user chooses not to enter data into these textboxes(textbox = ""), an entry on the db is created with null values. It works.
But sometimes the user wants to enter 0 as either an upper or lower end of a range. This is where my problem comes in. My program saves 0 as null too.
In my program I do a test on the textboxes and populate two float values in a business object (objQuestion) accordingly, like this:
//properties public float RangeFrom { get { return cvintRangeFrom; } set { cvintRangeFrom = value; } }
public float RangeTo { get { return cvintRangeTo; } set { cvintRangeTo = value; } }
// some code deleted for readability....
public int AddOption() { string cvstrSpName = "addOption"; SqlParameter [] cvstrStoredParams = SqlHelperParameterCache.GetSpParameterSet(gcstrConnectionString, cvstrSpName, true); //lines deleted for readability... //check if the optional fields have a value associated with them. if not, assign dbnull.value. cvstrStoredParams[4].Value=(cvintRangeFrom != Convert.ToSingle(null) ? cvintRangeFrom : (object)DBNull.Value); cvstrStoredParams[5].Value=(cvintRangeTo != Convert.ToSingle(null) ? cvintRangeTo : (object)DBNull.Value); //lines deleted for readability... SqlHelper.ExecuteNonQuery(gcstrConnectionString, CommandType.StoredProcedure, cvstrSpName, cvstrStoredParams); return(cvintOptionID = Convert.ToInt32(cvstrStoredParams[0].Value)); }
I use Convert.ToSingle when working with nulls (or possible nulls) because I get an error when I use float.parse for this.
The thing is, after this method AddOption has been executed, I test the value if the business object's rangefrom (that is where I entered 0) and display it on my form. I still shows a 0, but on my database table it is null!
objQuestion.AddOption(); //txtrangefrom.Text=""; on the next line I test the value in the business object... txtrangefrom.Text=objQuestion.RangeFrom.ToString(); // and this displays 0!!! //txtrangeto.Text=""; txtrangeto.Text=objQuestion.RangeTo.ToString();
So to me it seems the problem seems to be either the DAAB or on the SQL side, but hopefully somebody can prove me wrong! I was thinking that it could also be float.parse/Convert.ToSingle methods and have done various tests, but I am none the wiser... Any help or ideas will be greatly appreciated...
I haven't tested it, because at the moment I can't access my SQL database I know this is probably a stupid question, but...How can I test for DBNull when I'm using SqlDataReader.Item(string)? I use to check it using: if(!reader.IsDBNull(2)) ...But I have found that can not count on a particular ordinal reference because some of the stored procedures select the columns in different orders. can I do something like: if(reader["Column1"] != DBNull.Value)or with the reader["Column1"] throw an error because it is not found?? I too hate when people ask questions that they could test themselves...but I can't really test it at the moment. Any input would be greatly appreciated.
Hi! I was trying to use the ?? operator with an DBDatareader. eg: long lValue = Convert.ToInt32(objReader["ParentID"] ?? -1); which throws the following exception: "... Object cannot be cast from DBNull to other types."I think the reason is, that DBNull.Value isn´t actually null. Therefore I changed my code to: long lValue = objReader["ParentID"] != DBNull.Value ? Convert.ToInt32(objReader["ParentID"]) : -1; Is there a better way of doing this ? Can one use the ?? operator with a Datareader anyway? Thanks for your help! PS: sorry for my poor english.
Hi, I have built a few pages and a stored procedure and a class on the back of a SQL2000 dbase. and I get the following error:
Cast from type 'DBNull' to type 'String' is not valid. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.InvalidCastException: Cast from type 'DBNull' to type 'String' is not valid.Source Error:
Line 111: Dim myWorkJobs As WorkJobsDATA = New WorkJobsDATA Line 112: Line 113: myWorkJobs.CustomerID = CStr(parameterCustomerID.Value) Line 114: myWorkJobs.WorkID = CStr(parameterWorkID.Value) Line 115: myWorkJobs.DateOfQuote = CStr(parameterDateOfQuote.Value).Trim() Source File: C:InetpubwwwrootCommerceComponentsWorkJobs.vb Line: 113
My Database has 1 line of data (for testing) and all fields are populated. I am Querying a column called IndividualID which has a value of 3425243 at the moment. This is hardcoded in the aspx.vb at the moment. ASPX VB: Public Class WorkRequest Inherits System.Web.UI.Page Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 'Put user code to initialize the page here End Sub Private Sub btnEnter_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEnter.Click 'for now, send this value (stored in dbase under individualID) to the querystring Dim IndividualID As String = "3425243" Response.Redirect("WorkRequestMain.aspx?IndividualID=" & IndividualID) End SubEnd Class
COMPONENTSWorkJobs.vb (This is the class file)
Imports SystemImports System.ConfigurationImports System.DataImports System.Data.SqlClient Namespace ASPNET.StarterKit.Commerce Public Class WorkJobsDATA Public CustomerID As String Public WorkID As String Public DateOfQuote As String Public QuoteAmount As String Public Title As Decimal Public FirstName As String Public Surname As String Public FirstLine As String Public District As String Public Town As String Public Postcode As String Public Telephone As String Public Requirements As String Public WorkRequired As String Public EmailAddress As String End Class Public Class WorkJobs Public Function GetWorkDetails(ByVal IndividualID As String) As WorkJobsDATA Dim myConnection As SqlConnection = New SqlConnection(ConfigurationSettings.AppSettings("ConnectionString")) Dim myCommand As SqlCommand = New SqlCommand("SP_PendingQuotes", myConnection) ' Mark the Command as a SPROC myCommand.CommandType = CommandType.StoredProcedure ' Add Parameters to SPROC Dim parameterIndividualID As SqlParameter = New SqlParameter("@IndividualID", SqlDbType.NVarChar, 50) parameterIndividualID.Value = IndividualID myCommand.Parameters.Add(parameterIndividualID) Dim parameterCustomerID As SqlParameter = New SqlParameter("@CustomerID", SqlDbType.BigInt, 8) parameterCustomerID.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterCustomerID) Dim parameterWorkID As SqlParameter = New SqlParameter("@WorkID", SqlDbType.NVarChar, 50) parameterWorkID.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterWorkID) Dim parameterDateOfQuote As SqlParameter = New SqlParameter("@DateOfQuote", SqlDbType.DateTime, 8) parameterDateOfQuote.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterDateOfQuote) Dim parameterQuoteAmount As SqlParameter = New SqlParameter("@QuoteAmount", SqlDbType.Money, 8) parameterQuoteAmount.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterQuoteAmount) Dim parameterTitle As SqlParameter = New SqlParameter("@Title", SqlDbType.NVarChar, 50) parameterTitle.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterTitle) Dim parameterFirstName As SqlParameter = New SqlParameter("@FirstName", SqlDbType.NVarChar, 50) parameterFirstName.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterFirstName) Dim parameterSurname As SqlParameter = New SqlParameter("@Surname", SqlDbType.NVarChar, 50) parameterSurname.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterSurname) Dim parameterFirstLine As SqlParameter = New SqlParameter("@FirstLine ", SqlDbType.NVarChar, 50) parameterFirstLine.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterFirstLine) Dim parameterDistrict As SqlParameter = New SqlParameter("@District", SqlDbType.NVarChar, 50) parameterDistrict.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterDistrict) Dim parameterTown As SqlParameter = New SqlParameter("@Town", SqlDbType.NVarChar, 50) parameterTown.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterTown) Dim parameterPostcode As SqlParameter = New SqlParameter("@Postcode", SqlDbType.NVarChar, 50) parameterPostcode.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterPostcode) Dim parameterTelephone As SqlParameter = New SqlParameter("@Telephone", SqlDbType.NVarChar, 50) parameterTelephone.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterTelephone) Dim parameterRequirements As SqlParameter = New SqlParameter("@Requirements", SqlDbType.NVarChar, 3500) parameterRequirements.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterRequirements) Dim parameterWorkRequired As SqlParameter = New SqlParameter("@WorkRequired", SqlDbType.NVarChar, 3500) parameterWorkRequired.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterWorkRequired) Dim parameterEmailAddress As SqlParameter = New SqlParameter("@EmailAddress", SqlDbType.NVarChar, 100) parameterEmailAddress.Direction = ParameterDirection.Output myCommand.Parameters.Add(parameterEmailAddress) myConnection.Open() myCommand.ExecuteNonQuery() myConnection.Close() parameterEmailAddress.Value.GetType() Dim myWorkJobs As WorkJobsDATA = New WorkJobsDATA myWorkJobs.CustomerID = CStr(parameterCustomerID.Value) myWorkJobs.WorkID = CStr(parameterWorkID.Value) myWorkJobs.DateOfQuote = CStr(parameterDateOfQuote.Value).Trim() myWorkJobs.Title = CStr(parameterTitle.Value).Trim() myWorkJobs.FirstName = CStr(parameterFirstName.Value).Trim() myWorkJobs.Surname = CStr(parameterSurname.Value).Trim() myWorkJobs.FirstLine = CStr(parameterFirstLine.Value).Trim() myWorkJobs.District = CStr(parameterDistrict.Value).Trim() myWorkJobs.Town = CStr(parameterTown.Value).Trim() myWorkJobs.Postcode = CStr(parameterPostcode.Value).Trim() myWorkJobs.Telephone = CStr(parameterTelephone.Value).Trim() myWorkJobs.Requirements = CStr(parameterRequirements.Value).Trim() myWorkJobs.WorkRequired = CStr(parameterWorkRequired.Value).Trim() myWorkJobs.EmailAddress = CStr(parameterEmailAddress.Value).Trim() Return myWorkJobs End Function End ClassEnd Namespace
Dear GroupI'm having a very weird problem. Any hints are greatly appreciated.I'm returning two values from a MS SQL Server 2000 stored procedure to myASP.NET Webapplication and store them in sessions.Like This:prm4 = cmd1.CreateParameterWith prm4..ParameterName = "@Sec_ProgUser_Gen"..SqlDbType = SqlDbType.VarChar..Size = 10..Direction = ParameterDirection.OutputEnd Withprm5 = cmd1.CreateParameterWith prm5..ParameterName = "@Sec_ProgUser_Key"..SqlDbType = SqlDbType.VarChar..Size = 10..Direction = ParameterDirection.OutputEnd With....cmd1.ExecuteNonQuery()....Session("Sec_ProgUser_Gen") = prm4.ValueSession("Sec_ProgUser_Key") = prm5.ValueBoth output parameters are declared as varchar(10) within the storedprocedure. If I run the stored procedure in SQL Analyzer, I'm getting astring value for each of them. E.g. @Sec_ProgUser_Gen is "1110011",@Sec_ProgUser_Key = "1100".Now the strange thing happens if I try to run the following code:Sub MyTest()Dim MyString1 As StringDim MyString2 As StringMyString1 = CStr(Session("Sec_ProgUser_Key"))....MyString2 = CStr(Session("Sec_ProgUser_Gen"))End SubIt fails in line 'MyString2 = CStr(Session("Sec_ProgUser_Gen"))' with Castfrom type 'DBNull' to type 'String' is not valid.I don't understand this. They are both the same, the only difference is thelength of the string. Help!Additional Information:The values for @Sec_ProgUser_XXX are created in the stored procedure with astatement like this:SET @Sec_ProgUser_Key = (SELECT Convert(varchar(1),Key_CanCreateKey) +Convert(varchar(1),Key_CanCreateTransaction) +Convert(varchar(1),Key_CanView) + Convert(varchar(1),Key_CanDelete) FROMi2b_proguser_securityprofile WHERE SecurityProfileID = @SecurityProfileID)The datatype of the source columns used to be bit then changed them toInteger as I thought this might cause the problem. (Although it shouldn't asthe values get converted to varchar without a problem in the storedprocedure. No fields contain NULL values, only 1 or 0.
I am developing the database application. This is a live database and is being used by the customer. I am to release a new version and I had to add new columns to fit the requirements DateStarted (DateTime), and TotalHours(Int) into a database table.There are already over a 1000 rows in this table.
When the customer wants to look at a record in this table and insert the value into the text boxes (Front-end), when it gets to the DateStarted or TotalHours it comes up with a error message:"
The value for column 'DateStarted' in table 'IncidentTask' is DBNull."The method for inserting is:
What are the possible solutions to this problem? Would it mean checking for a DBNULL before displaying in the textboxes? Or updating the new column rows with an date:
Code Snippet
UPDATE IncidentTask SET DateStarted = '1/1/2005' WHERE (DateStarted IS NULL)
Hi,I have a stored procedure which returns an integer indicating whether the operation has succeeded or failed. It does this by calling set @returnvalue = (0 or 1) then select @returnvalue as returnvalue in the stored procedure code. When I run the stored procedure, inputting a set of parameters as it expects, it does what it's supposed to do and outputs a table with a single row and a single column, called returnvalue, which has a value of either 1 or 0. When I run the stored procedure through a function in asp, using the exact same set of parameters, output the results as a data set and try and convert the return as an integer I get the following error: "Object Cannot be cast from DBNull from other types"The conversion code is ..return Convert.ToInt32(ds.Tables[0].Rows[0]["returnvalue"]);And if I change "returnvalue" to anything else (like "wibble" for example) then I get a different error telling me it can't find the column named "wibble". So the dataset definitely contains a table with a column in it called returnvalue, as you expect. But it's value is, apparently, DBNull instead of an integer.How come this works when called directly through SQL and fails when called through ASP? Can anyone help? This is really doing my head in!Cheers,Matt
Ok well i have a stored procedure that returns an integer between 1 and 5. My problem now is i want to check to see if the table will return NULL and if so i don't want to assign the value to my variable otherwise it'll trow an error. My code is listed below but i keep getting the error "Conversion from type 'DBNull' to type 'Integer' is not valid." i've also tried If getoptionpicked.Parameters("@optionpicked").Value = Nothing ThenIf getoptionpicked.Parameters("@optionpicked").Value Is system.dbnull Then below is the rest of the code If getoptionpicked.Parameters("@optionpicked").Value Is Nothing Then Else optionpicked = getoptionpicked.Parameters("@optionpicked").Value If optionpicked = 1 Then option1.Checked = True ElseIf optionpicked = 2 Then option2.Checked = True ElseIf optionpicked = 3 Then option3.Checked = True ElseIf optionpicked = 4 Then option4.Checked = True ElseIf optionpicked = 5 Then option5.Checked = True Else End If End If
I have quite a few tables which allow NULL values. I have to struggle a lot with DBnull Exceptions :|example: col1,col2,... are all columns of type Integer and possibly NULL. var query = from person in table select new { person.col1, test = (int?) person.col2, person.col3, person.col4, ...}; As soon as my result encounters a DBNull value.. the whole query fails. This is really bad.How would I return the valid values.. and set the keys where there is no value to a null type? (e.g. int -> 0)I tried using "(int?)" but I'm not *really* sure what it does :-) Anyway.. it has no effect :-)
I'm creating an ISP for extractig data from a text file and put it in a database.
One of the fields in my textfile contains the value '0' or a date. If it's '0' it should be converted to the Null Value. The column in which it has to be saved is of type smalldatetime.
This is the code of my script where I want to check the value of the field in my textfile and convert it to a date or to Null.
Public Overrides Sub Input0_ProcessInputRow(ByVal Row As Input0Buffer)
If Row.cdDateIn = "" Or Row.cdDateIn= "0" Then
Row.cdDateInCorr = CDate(DBNull.Value)
ElseIf Row.cdDateIn_IsNull Then
Row.cdDateInCorr = CDate(DBNull.Value)
Else
Row.cdDateInCorr = CDate(Row.cdDateIn)
End If
End Sub
The error that I get is:
Validation error. Extract FinCD: Conversion of cdDateIn [753]: Eroor 30311: Value of type 'System.DBNull' cannot ben converted to 'Date'.
I´m exporting an ms-excel file, then I use a lookup transformation to get a field from a SQL Server 2005 table. The Lookup transformation editor, after selecting the table, shows a warning that says:
at least one mapping between a column from available input columns ans a column from available lookup columns must be defined on the columns page.
So I try to make a relationship in the Lookup transformation editor's column tab where I find the Available input columns and the available lookup columns but I get the following error:
The following columns cannot be mapped: [Department, DEP_CLEGALCODE] One or more columns do not have supported data types, or their data types do not match.
The field in SLQ Server is varchar(10) and the input field is a derived column transformation; I have tried different Data Types but I always have the same error.
The DataFlow is: ExcelSource --> Derived Column --> Lookup --> Flat file destination
Hello Friends How are you?? Friends i am getting problem in SQL Server 2005. I am deployng web application on production server as well as Databse also. In production server i inserted new field in all tables which is rowguid and its type is uniqueidentifier. The default binding for this field is newsequentialid(). In some pages it works ok but in some places it generates error like 'Conversion from type 'DBNull' to type 'String' is not valid'. Can anybody help me to solve this problem. Its urgent so plz reply me as soon as possible. I'll be very thankfull to you. Thanks in Advance. Regards,
Hi, I have developed a custom server control for .NET Framework 2.0. The server control has a property named BinaryData of type byte[]. I marked this property to be data bindable. Now, I have varbinary(Max) type of field in my SQL Database and I have used SQLDataSource and bound this varbinary(Max) field with the property BinaryData (byte[]) of my control. It is working fine as long as the data value is not NULL. Now, In my control, I have handled the NULL value so that no Exception is thrown. Still, when I bind this property using the SQLDataSource, I get Error "Unable to cast object of type 'System.DBNull' to type 'System.Byte[]'." I am not sure if I can do anything to stop this erro within my control. If it is not possible from the control, then what is the workaround that I can do in my ASPX page in order to stop this error ? Thanks a lot in advance.
is there anyway to retrieve the database properties and display in an asp.net web form as a quick over view rather than logging onto the server to check, items such as size, space available, last backup data etc? Cheers
Hi and thanks for your help specifying the default database means what. for instance when I add alog in user and I have to choose a default database. Does it make a difference if the Default database is Master or any other user database name. What is the significant to select Master vs any other database.
Hello! We are having problems with a single SQL Server where the Server properties will not save, and always revert to the default. It occurs only on those tabs with "configured" and "running" options at the bottom. Other tabs will keep the settings we custom. The big problem is with the memory and processor tabs which even when we've made only a single change and stopped and started the service, reverts back to a default. Any clues - we are logged in as "sa" and have not removed the SA priviledges.
Plz help me to know whats wrong with following script:
EXEC sp_addextendedproperty @name = 'col_Programs_ID_Description', @Value = 'The Unique Identifier for a specific Program', @level1Type = 'Programs', @level2Type = 'ID'
I get the following error: Server: Msg 15600, Level 15, State 1, Procedure sp_addextendedproperty, Line 42 An invalid parameter or option was specified for procedure 'sp_addextendedproperty'.
NOTE: If I dont use the last 2 parameters this procedure runs fine, but it adds the Extended Property to the Database Level while I'm trying to add it to the TABLE-->COLUMN level.
We installed an application named Streamserve. Now, if I go into Enterprise Manager I can expand the databases fine. But when I try to right-click properties Enterprise Manager goes bye bye. No error messages. I tried this on master and same thing. I currently have 2 different machines - a dev and a QA box and both are behaving badly.
