VB.NET update same table inside a DataReader loop - sql

Question

I'm reading from a SQL database and depending on the fields I check I need to update a different field in that same table. I'm looping through the dataset and trying to send an UPDATE back while looping. It worked on my TEST table but isn't working for my production table. When I execute the "ExecuteNonQuery" command, I get a timeout expired error. If I actually close the first connection and then call the ExecuteNonQuery it runs instantly.
Here's the code...
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim sqlConn As New SqlConnection
Dim sqlComm As New SqlCommand
Dim sqlDR As SqlDataReader
sqlConn.ConnectionString = "Data Source=10.2.0.87;Initial Catalog=Inbound_Orders_DB;User ID=xxxxx;Password=xxxxxx;"
sqlConn.Open()
sqlComm.CommandText = "SELECT * FROM RH_Orders where Order_DateTime is NULL ORDER by Order_Date DESC"
sqlComm.Connection = sqlConn
sqlDR = sqlComm.ExecuteReader
If sqlDR.HasRows Then
While sqlDR.Read
If Trim(sqlDR("Order_Date")) <> "" Then
Dim order_Date As String = Trim(sqlDR("Order_Date"))
Dim order_DateTime As String = ""
If Len(order_Date) = 14 Then
order_DateTime = order_Date.Substring(0, 4) & "-" & order_Date.Substring(4, 2) & "-" & order_Date.Substring(6, 2) & " "
order_DateTime = order_DateTime & order_Date.Substring(8, 2) & ":" & order_Date.Substring(10, 2) & ":" & order_Date.Substring(12, 2)
Dim myId As String = sqlDR("ID")
Dim sqlConn2 As New SqlConnection
Dim sqlComm2 As New SqlCommand
sqlConn2.ConnectionString = "Data Source=10.2.0.87;Initial Catalog=Inbound_Orders_DB;User ID=xxxx;Password=xxxx;"
sqlConn2.Open()
sqlComm2.CommandText = "UPDATE [RH_Orders] SET order_DateTime = '" & order_DateTime & "' WHERE ID=" & myId
sqlComm2.Connection = sqlConn2
sqlComm2.ExecuteNonQuery()
sqlConn2.Close()
End If
End If
End While
End If
End Sub
End Class

Answer 1

Use parametrized queries and don't concatenate strings, then use a SqlParameter with SqlDbType.Datetime and assign a real DateTime instead of a formatted string.
But maybe it would be more efficient here to fill a DataTable with SqlDataAdapter.Fill(table), loop the table's Rows, change each DataRow and use SqlDataAdapter.Update(table) to send all changes in one batch after the loop. No need for the SqlDataReader loop.
For example (untested):
Using con = New SqlConnection("Data Source=10.2.0.87;Initial Catalog=Inbound_Orders_DB;User ID=xxxxx;Password=xxxxxx;")
Using da = New SqlDataAdapter("SELECT * FROM RH_Orders where Order_DateTime is NULL ORDER by Order_Date DESC", con)
da.UpdateCommand = New SqlCommand("UPDATE RH_Orders SET order_DateTime = #order_DateTime WHERE ID = #Id", con)
da.UpdateCommand.Parameters.Add("#order_DateTime", SqlDbType.DateTime).SourceColumn = "order_DateTime"
Dim table = New DataTable()
da.Fill(table)
For Each row As DataRow In table.Rows
Dim orderDate = row.Field(Of String)("Order_Date")
Dim orderDateTime As DateTime
If DateTime.TryParse(orderDate.Substring(0, 4) & "-" & orderDate.Substring(4, 2) & "-" & orderDate.Substring(6, 2), orderDateTime) Then
row.SetField("order_DateTime", orderDateTime)
End If
Next
da.Update(table)
End Using
End Using
Side-note: Instead of building a new string "2017-01-31" from "20170131" you could also use DateTime.TryParseExact:
DateTime.TryParseExact("20170131", "yyyyMMdd", nothing, DateTimeStyles.None, orderDateTime)