Retrieve Data from Stored Procedure - sql-server

Question

I seem to be having troubles with my stored procedure call here. I'm trying to get all my information from a stored procedure, which returns a single column into a datatable. I've followed along for most solutions here and can't seem to figure out why it is not working. My data table has a primary key constraint on it, due to having multiple values in it. But, from what I've read, this isn't necessary as the Fill on the SqlDataAdapter will just merge those changes if there is any?
Here is my code so far:
Dim dtValues As New DataTable()
Dim dtCol As New DataColumn()
dtCol.ColumnName = "ReferenceID"
dtCol.DataType = GetType(SqlInt32)
dtCol.AllowDBNull = False
dtValues.Columns.Add(dtCol)
dtValues.PrimaryKey = {dtCol}
Public Shared Sub ExecStoredProc(ByVal ProcName As String, ByRef connection As SqlConnection, ByRef dtValues As DataTable, ByVal ParamArray args() As Object)
Dim sqlCommand As New SqlCommand()
For i = 0 To args.Length - 1 Step 2
sqlCommand.Parameters.AddWithValue(CStr(args(i)), args(i + 1))
Next
sqlCommand.CommandText = ProcName
sqlCommand.CommandType = CommandType.StoredProcedure
sqlCommand.Connection = connection
Dim sqlAdp As New SqlDataAdapter(sqlCommand)
' Fill the table to mess around with.
sqlAdp.Fill(dtValues)
End Sub
However, the error that I get is:
Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.
My stored procedure I'm calling is a simple
Select ID
From TableName
Where Reference = #Reference
with no conditions really, and I've tested and it returns about 19 unique records.
Any help would be appreciated, thanks!

Answer 1

You are defining a not null primary key data column in your table called "ReferenceID":
Dim dtCol As New DataColumn()
dtCol.ColumnName = "ReferenceID"
dtCol.DataType = GetType(SqlInt32)
dtCol.AllowDBNull = False
However, your sql query is not selecting a 1ReferenceID1 column, it is selecting a column named ID:
Select ID
From TableName
Where Reference = #Reference
Therefore, when you go to fill your table you get the error:
Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.
Because the not-null, unique constraint you set on "ReferenceID" is being violated.
Change your query to:
Select ID as [ReferenceId]
From TableName
Where Reference = #Reference
And you should be set (assuming that that ID is unique and not null)