"variable" is not declared error - sql

Question

Image of the error
I am new to Vb.net programing and I need a little help here, I pretend to send info to my database, the first query gives me the id I need and I declare it as "postoid", when I later try to call it (in the insert into part) it says it is not declared, I have googled the problem a hundred times but I couldn't find the answer.
Ps: this code is all in the same private sub
Try
mysqlconn.Open()
queryrow = "Select * from postos where postos_nome ='" & TextBox1.Text & "'"
COMMANDuser1 = New MySqlCommand(queryrow, mysqlconn)
READERuser = COMMANDuser1.ExecuteReader
While READERuser.Read
Dim postoid = READERuser.GetString("postos_id")
End While
mysqlconn.Close()
Catch ex As Exception
End Try
Dim sqlquery As String = "INSERT INTO computadores VALUES (0,'" & pcname.ToUpper & "','" & ip & "','" & so & "','" & cpu & "','" & ram & "','" & gc & "','" & wserial & "','" & mnome & "','" & mserial & "','" & "--- ,,'Inativo','" & empresaid & "','" & postoid & "','" & userid & "')"
Dim sqlcommand As New MySqlCommand
With sqlcommand
.CommandText = sqlquery
.Connection = mysqlconn
.ExecuteNonQuery()
End With
MsgBox("Computador Adicionado")
Dispose()
Close()

Answer 1

Your variable postoid is out-of-scope outside the block it is declared in.
All you need to do is declare it outside the Try structure:
Dim postoid As String = ""
queryrow = "Select postos_id from postos where postos_nome = #PostosNome"
Using COMMANDuser1 As New MySqlCommand(queryrow, mysqlconn)
COMMANDuser1.Parameters.Add("#PostosNome", TextBox1.Text)
mysqlconn.Open()
READERuser = COMMANDuser1.ExecuteReader()
While READERuser.Read
postoid = READERuser.GetString("postos_id")
End While
mysqlconn.Close()
End Using
If postoid <> "" Then
' perform the insert...
I did not actually use Try in that, as you have no code in your Catch block - having no code in the Catch block has the effect of hiding errors. You want to see the errors.
For using SQL parameters, see, e.g., Inserting data into a MySQL table using VB.NET but please use .Add instead of .AddWithValue - the latter will not always work as intended.