insert or update with single button in vb.net - vb.net

Question

how to insert and update data in database(sql server) with single button in vb.net i tried but not get the result.
here is my code.......
Private Sub Button5_Click(sender As System.Object, e As System.EventArgs) Handles Button5.Click
Try
Dim reader As SqlDataReader
Dim query As String
Dim n As Integer
n = 0
sqlcom1 = New SqlCommand("select * from mydatabase.masters")
sqlcom1.ExecuteReader()
sqlcom = New SqlCommand("select * from mydatabase.masters")
sqlcom.ExecuteReader()
reader = sqlcom1.ExecuteReader
reader = sqlcom.ExecuteReader
sqlcom = New SqlCommand("Update masters SET EmpName=#EmpName, Age=#Age, Address=#Address where Empid=#Empid", conn)
sqlcom.Parameters.Add("#EmpName", SqlDbType.VarChar).Value = TextBox4.Text
sqlcom.Parameters.Add("#Age", SqlDbType.Int).Value = TextBox3.Text
sqlcom.Parameters.Add("#Address", SqlDbType.VarChar).Value = TextBox2.Text
sqlcom.Parameters.Add("#Empid", SqlDbType.Int).Value = TextBox1.Text
sqlcom1 = New SqlCommand("insert into masters(Empid, EmpName, Age, Address) values(#Empid, #EmpName, #Age, #Address)", conn)
sqlcom1.Parameters.AddWithValue("#Empid", TextBox1.Text)
sqlcom1.Parameters.AddWithValue("#EmpName", TextBox4.Text)
sqlcom1.Parameters.AddWithValue("#Age", TextBox3.Text)
sqlcom1.Parameters.AddWithValue("#Address", TextBox2.Text)
conn.Open()
While reader.Read
n = n + 1
End While
If table.Rows.Count = n Then
sqlcom1.ExecuteNonQuery()
ElseIf table.Rows.Count = n + 1 Then
sqlcom.ExecuteNonQuery()
End If
Catch ex As Exception
MessageBox.Show("error" + ex.Message)
End Try
End Sub

Answer 1

Using block ensures that your connection object is closed and disposed even if there is an error.
Normally I put comments in line but the code got so cluttered that had to move most of them up here. I hope you can figure out where they belong.
Dim reader As SqlDataReader - Unused
Dim query As String - Unused
Integers are automatically initialized to zero
Pass the query and the connection to the constructor of the command.
Your connection string will tell SQL Server what database to use. It is not necessary in the query.
Apparently all you want is the count, not all the data.
This query is exactly the same as sqlcom1
Dim sqlcom As New SqlCommand("select * from mydatabase.masters", cn)
sqlcom.ExecuteReader()
You did this twice
reader = sqlcom1.ExecuteReader
Not necessay, we already retrieved the count
`While reader.Read
n = n + 1
End While`
I made the assumption that table was a DataTable populated at some other time. Using the count as comparison to the count in the table is not a great way to determine if the command is Insert or Update but it might work as long as database and table were not used with a DataAdapter that updated the database.
Private Sub Button5_Click(sender As System.Object, e As System.EventArgs) Handles Button5.Click
Try
Dim n As Integer
Using cn As New SqlConnection("Your connection string")
Dim sqlcom1 As New SqlCommand("select Count(*) from masters", cn)
cn.Open()
n = CInt(sqlcom1.ExecuteScalar) 'n is now the number of rows in the database table
Dim sqlcom As New SqlCommand
sqlcom.Parameters.Add("#EmpName", SqlDbType.VarChar).Value = TextBox4.Text
'Age is not a good idea to enter in a database. It changes over time.
'Enter the birth date and calculate the age as needed.
sqlcom.Parameters.Add("#Age", SqlDbType.Int).Value = CInt(TextBox3.Text)
sqlcom.Parameters.Add("#Address", SqlDbType.VarChar).Value = TextBox2.Text
If table.Rows.Count > n Then
'Normally EmpId would be an auto increment (identity) field
'and would NOT be included in an insert.
sqlcom.CommandText = "insert into masters(EmpName, Age, Address) values(#EmpName, #Age, #Address)"
Else
sqlcom.CommandText = "Update masters SET EmpName=#EmpName, Age=#Age, Address=#Address where Empid=#Empid"
sqlcom1.Parameters.Add("#Empid", SqlDbType.Int).Value = CInt(TextBox1.Text)
End If
sqlcom.ExecuteNonQuery()
End Using
Catch ex As Exception
MessageBox.Show("error" + ex.Message)
End Try
End Sub
On second thought, forget the whole thing. Use a DataGridView and a DataAdapter. Then you can just use Update and it will update, insert and delete.