将VB.net IF语句与SQL值一起使用

Question

I am trying to use an IF statement to do a certain action if my SQL value is greater than 1.

However when I run the below code, it returns an error.

Operator '>' is not defined for types 'System.Data.SqlClient.SqlCommand' and 'Integer'.

Here is the code:

Using cmdb = New SqlCommand("INSERT INTO AdditionalDaisyCodes (AddCode) VALUES (@AddCode)", con)
  con.Open()
  cmdb.ExecuteNonQuery()
  con.Close()

  If cmdb > 1 Then

    MessageBox.Show("Duplicate Codes Exist!", "Indigo Billing", _
    MessageBoxButtons.OK, MessageBoxIcon.Information)

  Else
  End If
End Using

Can anybody help with the correct syntax?

Answer 1

Use this

   int result=cmdb.ExecuteNonQuery();
if result > 1 then
//code here
else
end if

Answer 2

You have a bigger problem than just a syntax error. Based on your posted code, it looks like you want to inform the user that duplicate codes exist. Since you have an Else , I'm going to make a guess and say that if duplicate codes aren't found, you want the insertion made.

Currently the number of rows affected by ExecuteNonQuery() will never be greater than 1. In addition, in your posted code you never assign a value to the @AddCode parameter - if the AddCode column cannot be null, that could cause an error.

What you probably want to do is to check to see if the code exists, and if not then add it. Something like this would do the trick:

Using cmdb = New SqlCommand("SELECT * FROM AdditionalDaisyCodes WHERE AddCode = @AddCode", con)
    con.Open()

    cmdb.Parameters.AddWithValue("@AddCode", txtAddCode.Text)
    Dim reader As SqlDataReader = cmdb.ExecuteReader()

    If reader.HasRows Then
        MessageBox.Show("Duplicate Codes Exist!", "Indigo Billing", _
MessageBoxButtons.OK, MessageBoxIcon.Information)

    Else
        cmdb.CommandText = "INSERT INTO AdditionalDaisyCodes(AddCode) Values(@AddCode)"
        cmdb.Parameters.AddWithValue("@AddCode", txtAddCode.Text)
        cmdb.ExecuteNonQuery()

    End If

    con.Close()
End Using

txtAddCode.Text in the above example is assuming the code is coming from a TextBox named txtAddCode . First it checks to see if the code is already in the table by running a SELECT query restrained by a WHERE clause. If the returned SqlDataReader has rows, then that code is already in the table and the message box is displayed.

If the SqlDataReader does not have rows, then the code is not in the table and cmdb is reused to do the insert.

Also note that you can put the SqlConnection in a Using block as well, eliminating the need to call Close() on the connection explicitly.