I have a problem with something I have done many times but this time it just doesn't work.
This is what what I am trying to do (in Visual Studio 2003 and VB.NET)
Earlier in the code:
Private SaveCustomerInformationCommand As System.Data.SqlClient.SqlCommand
Then this in a setup process:
SaveCustomerInformationCommand = New System.Data.SqlClient.SqlCommand("spSaveCustomerInformation")
SaveCustomerInformationCommand.CommandType = Data.CommandType.StoredProcedure
Dim custIdParameter As System.Data.SqlClient.SqlParameter = SaveCustomerInformationCommand.CreateParameter()
custIdParameter.ParameterName = "#CustId"
custIdParameter.SqlDbType = Data.SqlDbType.Int
custIdParameter.Direction = Data.ParameterDirection.Input
SaveCustomerInformationCommand.Parameters.Add(custIdParameter)
And then later:
SaveCustomerInformationCommand.Parameters.Item("#CustId").Value = myValue
And I get this:
System.IndexOutOfRangeException: An SqlParameter with ParameterName '#CustId' is not contained by this SqlParameterCollection.
Any ideas/solutions?
AFAIK, the "#" is not technically part of the name of the parameter... rather it's what you put into your T-SQL to denote that a parameter name is coming afterwards. So I think you'll want to refer to it like this instead (with no "#") :
SaveCustomerInformationCommand.Parameters.Item("CustId").Value = myValue
You could also try the same thing when you initially insert the parameter name-- although since you're not getting an error there, I'd suspect the accessor call is to blame, not the inserter call.
Related
I have two Layes Classes Business Layer And Data Layer And i have The Main class i called DatabaseManager contain all functions i need for stored procedures
I search on these errors I cannot find solutions
First Error in DatabaseManager class is :
implicit conversion from object to integer
Public Function ExecuteScalar(ByVal sql As String) As Object
Dim cmd As New SqlCommand(sql) With {
.CommandType = CommandType.Text,
.Connection = Connection
}
Dim retval As Integer = ExecuteScalar(cmd)
Return retval
End Function
In Data Layer Class i have this code :
Friend Function Get_Last_Visits_Type(ByRef cmd As SqlCommand)
Dim retval As Integer
cmd = New SqlCommand("Get_Last_Visits_Type")
retval = dm.ExecuteScalar(cmd)
Return retval
End Function
I got two errors here
function without an 'as' clause return type of object assumed
And
implicit conversion from object to integer
When Form Loaded i put this code on Load action :
TxtVisitTypeID.Text = Val(p.Get_Last_Visits_Type)
And i got this error :
implicit conversion from Double to String
Thanks...
Quite a few problems here as mentioned in comments:
Avoid naming a function anything that is a reserved word in the scope of your project at the very least: ExecuteScalar is a method of SqlCommand so use something like MyExecuteScalar instead.
Dim retval As Integer = ExecuteScalar(cmd) probably should be Dim retval As Integer = cmd.ExecuteScalar() unless you want a recursion (which I doubt). (Refer 1.)
Turn Option Strict on in your project settings. As mentioned, ALWAYS have this on. (And I prefer to have Option Explicit on and Option Infer off as well for similar reasons.)
With compile options set as in 3. you will have (valid) compilation errors pertaining to type conversion (at least), with a good chance of resulting in working code once you fix them. Eg Dim retval As Integer = Ctype(cmd.ExecuteScalar(), Integer) (if you're sure that the result of the query will be Integer, otherwise you will need to test and/or error trap).
Connection isn't defined anywhere: .Connection = Connection. You don't pass it nor declare it.
Since retval is declared as an Integer then the return type can also be tightened up to Integer as well, rather than Object.
Your second function has no return type.
What is dm? Not declared/defined.
Consider using Using blocks to close-and-dispose of SQL connection and command on exit.
CommandType.Text is the default so you only need to state it by way of explanation.
Here's what I'd do with your first function:
Public Function MyExecuteScalar(ByVal sql As String) As Integer
Try
Using con As New SqlConnection(sql)
Using cmd As New SqlCommand(sql, con)
Return CType(cmd.ExecuteScalar(), Integer)
End Using
End Using
Catch
Return -1 ' Or something recognizable as invalid, or simply Throw
End Try
End Function
Addressing the first function:
This code is too abstract to be useful. The name of the function is bad. It appears to be recursive but the value you pass back to the function is not a string but a command. If the line of code is Dim retval As Integer = cmd.ExecuteScalar(), then .ExecuteScalar() returns an Object. You cannot convert an Object to an Integer without a conversion method. If you are declaring retval as an Integer why would you have typed your function As Object? I won't even get into the connection problem here. I suggest you delete the function and start again.
Addressing the second function:
Why are you passing the command ByRef? This function has no connection at all! How do you expect it to execute anything? Same problem with retval As Integer and ExecuteScalar returning an Object.
Again, delete and start again.
Now to the code in Form.Load:
Val went out with VB6. I can give unanticipated results. Guess what, Val returns a Double. A .Text property expects a string. Also you appear to be calling the function you showed us above. That function asks for the calling code to provide an argument, namely an SqlCommand object.
My suggestions:
Forget about layers and try to learn the basics of data access with ADO.net. Turn on Option Strict now and forever. Ask new questions with a single problem. Tell us what line the error occurs on. You have been advised before that functions require a datatype but it doesn't seem to sink in.
Dim StrSql = "update student set id=?"
Updated (StrSql,15)
Public Function Updated (ByVal strSql As String, ByVal ParamArray Parameters As String ())
For Each x In Parameters
cmd.Parameters.AddWithValue("?",x)
Next
cmd.ExecuteNonQuery()
End Function
You didn't leave us much to go on; as jmcilhinney points out, you need to add more detail to future questions. For example in this one you have code there that doesn't compile at all, doesnt mention the types of any variable, you don't give the name of the database...
...I'm fairly sure that "Incorrect syntax near" is a SQL Server thing, in which case you need to remember that it (re)uses named parameters, unlike e.g. Access which uses positional ones:
SQL Server:
strSql = "SELECT * FROM person WHERE firstname = #name OR lastname = #name"
...Parameters.AddWithValue("#name", "Lee")
Access:
strSql = "SELECT * FROM person WHERE firstname = ? OR lastname = ?"
...Parameters.AddWithValue("anythingdoesntmatterwillbeignored", "Lee")
...Parameters.AddWithValue("anythingdoesntmatterwillbeignoredalso", "Lee")
This does mean your function will need to get a bit more intelligent; perhaps pass a ParamArray of KeyValuePair(Of String, Object)
Or perhaps you should stop doing this way right now, and switch to using Dapper. Dapper takes your query, applies your parameters and returns you objects if you ask for them:
Using connection as New SqlConnection(...)
Dim p as List(Of Person) = Await connection.QueryAsync(Of Person)( _
"SELECT * FROM person WHERE name = #name", _
New With { .name = "John" } _
)
' use your list of Person objects
End Using
Yep, all that adding parameters BS, and executing the reader, and converting the results to a Person.. Dapper does it all. Nonquery are done like connection.ExecuteAsync("UPDATE person SET name=#n, age=#a WHERE id=#id", New With{ .n="john", .a=27, .id=123 })
http://dapper-tutorial.net
Please turn on Option Strict. This is a 2 part process. First for the current project - In Solution Explorer double click My Project. Choose Compile on the left. In the Option Strict drop-down select ON. Second for future projects - Go to the Tools Menu -> Options -> Projects and Solutions -> VB Defaults. In the Option Strict drop-down select ON. This will save you from bugs at runtime.
Updated(StrSql, 15)
Your Updated Function calls for a String array. 15 is not a string array.
Functions need a datatype for the return.
cmd.Parameters.AddWithValue("?", X)
cmd is not declared.
You can't possible get the error you mention with the above code. It will not even compile, let alone run and produce an error.
It is not very helpful to write a Function that is trying to be generic but is actually very limited.
Let us start with your Update statement.
Dim StrSql = "update student set id=?"
The statement you provided will update every id in the student table to 15. Is that what you intended to do? ID fields are rarely changed. They are meant to uniquely identify a record. Often, they are auto-number fields. An Update command would use an ID field to identify which record to update.
Don't use .AddWithValue. See http://www.dbdelta.com/addwithvalue-is-evil/
and
https://blogs.msmvps.com/jcoehoorn/blog/2014/05/12/can-we-stop-using-addwithvalue-already/
and another one:
https://dba.stackexchange.com/questions/195937/addwithvalue-performance-and-plan-cache-implications
Here is another
https://andrevdm.blogspot.com/2010/12/parameterised-queriesdont-use.html
Since you didn't tell us what database you are using I guessed it was Access because of the question mark. If it is another database change the connection, command and dbType types.
Using...End Using block ensures you connection and command are closed and disposed even if there is an error.
Private ConStr As String = "Your Connection String"
Public Function Updated(StudentNickname As String, StudentID As Integer) As Integer
Dim RetVal As Integer
Using cn As New OleDbConnection(ConStr),
cmd As New OleDbCommand("Update student set NickName = #NickName Where StudentID = #ID", cn)
cmd.Parameters.Add("#NickName", OleDbType.VarChar, 100).Value = StudentNickname
cmd.Parameters.Add("#ID", OleDbType.Integer).Value = StudentID
cn.Open()
RetVal = cmd.ExecuteNonQuery
End Using
Return RetVal
End Function
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Dim RowsUpdated = Updated("Jim", 15)
Dim message As String
If RowsUpdated = 1 Then
message = "Success"
Else
message = "Failure"
End If
MessageBox.Show(message)
End Sub
This code keeps your database code separated from user interface code.
I've started converting an application of mine to use Option Strict On. I've been doing the CStr,Ctype etc, and it's been going well.
SQLCommand.Parameters.AddWithValue("#TERMINATE", If(IsNothing(txtEarningsTerminated.DateValue), DBNull.Value, txtEarningsTerminated.DateValue))
Then I hit this. The txtEarningsTerminated.DateValue is a custom masked text box. When it's value is Nothing I don't want to store anything in the database. However, it states
Cannot infer a common type, and Option Strict On does not allow 'Object' to be assumed.
When I change DBNull.Value to "" or nothing, the error goes away. However as Nothing, it fails during runtime stating
The parameterized query '(#CONTROL int,#CLIENTCODE nvarchar(10),#NoBill int,#TERMINATE nv' expects the parameter '#TERMINATE', which was not supplied.
I want to put a NULL in the database. This value can be a date and then become a NULL.
How do I translate this so as to not produce an error under Option Strict On?
The reason is because operator If(condition, executeAndReturnIfTrue, executeAndReturnIfFalse) expects that both true and false expressions will return same type.
In your case you return DbNull type if true and String(or some other type you didn't mentioned) if result is false.
If create SqlParameter more explicitly, then you can use next approach:
Dim value As Object = Nothing
If txtEarningsTerminated.DateValue Is Nothing Then
value = DbNull.Value
Else
value = xtEarningsTerminated.DateValue
End If
Dim param As SqlParameter = New SqlParameter With
{
.ParameterName = "#TERMINATE",
.SqlDbType = SqlDbType.VarChar, 'Or use your correct type
.Value = value
}
As mentioned in the comments using AddWithValue will force ADO.NET to decide the sql type automatically for your value, which can lead in different problems. For example everytime you run same query with different values your query plan will be recompiled every time you change value.
You can create extension method for string
Public Module ExtensionsModule
Public Function DbNullIfNothing(this As String) As Object
If this Is Nothing Then Return DBNull.Value
Return this
End Function
End Module
Then use it instead of your "inline If method"
Dim value As String = Nothing
Dim param As SqlParameter = New SqlParameter With
{
.ParameterName = "#TERMINATE",
.SqlDbType = SqlDbType.VarChar,
.Value = value.DbNullIfNothing()
}
So the answer was obvious and in the error. I just had to encase the DBNull.Value in a Ctype Object
CType(DBNull.Value, Object)
And then the code would compile just fine.
Here's one way to do it (assuming you're using stored procedures in your database):
In the stored procedure you're calling, set the date input parameter to equal null, making it an optional field with a default value of null (#terminate DATETIME = NULL).
That way, if you don't include that parameter in your procedure call, the procedure won't fail.
Set the default value of the date field to DateTime.MinValue so it always has some value. Then you can test to see if it is equal to a date other than DateTime.MinValue. If it is a valid date value, add the line to include the date parameter to the procedure call. If it is equal to DateTime.MinValue, don't add the parameter to the call.
Using Crystal Report 9 and VB.Net
Report is running through stored procedure, I want to pass the data to stored procedure.
How to do it?
In VB6, i did like this.
Report.ReportFileName = REPPATH & "\Detail.rpt"
Report.StoredProcParam(0) = Did
Report.StoredProcParam(1) = Deed
Report.Action = 1
How to do it in vb.net?
I think something like the following should work:
SetDataSource have like 4 overrides that all take an IEnumerable like object as parameter. But this has been done with CR 13 for VS 2010... I hope you will find something like with CR 9.
Dim report As New CrystalReport1
Dim sqla = New SqlDataAdapter()
sqla.SelectCommand.Connection = New SqlConnection(sConnectionString)
sqla.SelectCommand = New SqlCommand("EXEC storedProcName #a, #b, #c")
sqla.SelectCommand.Parameters.Add("#a", paramA)
sqla.SelectCommand.Parameters.Add("#a", paramB)
sqla.SelectCommand.Parameters.Add("#a", paramC)
report.SetDataSource(sqla)
//'If you do not have parameters, you may use :
report.SetDataSource(New SqlDataAdapter("EXEC storedProcName ", sConnectionString))
report.Refresh()
EDIT : sqla.SelectCommand.Parameters.Add("#a", paramA) is depreciated in the CR13 version. sqla.SelectCommand.Parameters.AddWithValue("#a", paramA) is used instead.
I have some code like this:
Function GetTypeFromTableName(ByVal _TableName As String, ByVal _DataContext As DataContext)
Dim Mytype As Type = (From t In _DataContext.Mapping.GetTables Where t.TableName = "dbo." + _TableName Select t.RowType.Type).SingleOrDefault
Return Mytype
End Function
Dim DBA As New LINQDataContext
_TBLName="City"
TableType = GetTypeFromTableName(_TBLName, DBA)
CallByName(obj, "Code", CallType.Set,1)
Dim Equery = From T In DBA.GetTable(TableType) Select T
Equery = Equery.Where(Function(Oj1) Oj1 Is obj)
Dim oopp = From t In Equery Select CallByName(t, "CName", CallType.Get, Nothing)
oopp.ToList.Item(0) = Txt_Name.Text
DBA.SubmitChanges()
SubmitChanges do not work. What is wrong?
It looks like to me that you are selecting out a list of anonymous types, then changing the value in the list of anonymous types not in the matching object in the table. Since you haven't updated the table object itself, SubmitChanges has nothing to do.
Try changing it to the following
Dim matchingObj = Equery.Where( Function(Oj1) Oj1 Is obj )
.SingleOrDefault();
Then set the property value.
CallByName( matchingObj, "CName", CallType.Set, Txt_Name.Text );
Then submit your changes.
Note: I read VB ok, but I don't write it so well. You may need to fix up my syntax. You might also want to make sure that there is a matching object before you attempt to set it's property.
This is old but thought i will come and clear this up.
Whenever your update or Submitchanges fails try puttin InsertOnSubmit() statment. This statment will give you detailed error.
in my case I had very simple code.
var single = dataContext.MySysTables.FirstOrDefault();
single.DispatchIdIndex ++;
single.ModifyDate = DateTime.Now;
dataContext.SubmitChanges();
This was not being updated. When I put a InsertOnSubmit(single) line than it gave me error that "data can not be inserted because table does not have Primary key". This was my test table to i didnt have primary key. Once I added a new column and made a primary key than everything worked fine.
peace