No value given for one or more required parameters.

Hi, I have been using VB.net since last 6 months only. I have been going through the various forum replies on the captioned error but I wanted to post my query which is as under:

I have a combobox in which Location details are populated from access table1. Based on the user's selection of a location from the combobox, I want to select all the records of table1 where in value in location field equals selection from combobox and populate all those records in checked grid view. My code is as under:

Dim Conn As New OleDb.OleDbConnection
Dim sql1 As String
Dim command1 As New OleDb.OleDbCommand
Dim oleAdapter1 As New OleDb.OleDbDataAdapter
Dim UserDataSet1 As New DataSet
'Dim usid As String
'Dim x As Integer
Conn = New OleDb.OleDbConnection
Conn.ConnectionString = "provider = Microsoft.ACE.OLEDB.12.0;data source = c:\renuka\Project1\sewage pumps.accdb"
sql1 = "Select * from Table1 where Table1.Location = ComboBox7.text"
Conn.Open()
command1 = New OleDb.OleDbCommand(sql1, Conn)
command1.ExecuteNonQuery()
oleAdapter1 = New OleDb.OleDbDataAdapter("Select * From Table1 where Table1.Location = combobox7.text", Conn)
UserDataSet1 = New DataSet
oleAdapter1.Fill(UserDataSet1, "Table1")
DataGridView1.DataSource = UserDataSet1.Tables(0)

I have checked the spellings of my field, table etc but nothing seems amiss. I am getting the error "No value given for one or more required parameters just after sql1 select statement. Would really appreciate help on this.

Hi,

Your error is here:-

Code:

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oleAdapter1 = New OleDb.OleDbDataAdapter("Select * From Table1 where Table1.Location = combobox7.text", Conn)

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The way you have it now combobox7.text is being interpreted as a parameter since your Table1.Location column is a text field and you have not passed a Text value to the Where clause.

You should look into using parameters correctly rather than using string concatenation, but to solve your issue try this:-

Code:

---

oleAdapter1 = New OleDb.OleDbDataAdapter("Select * From Table1 where Table1.Location = '" & ComboBox7.Text & "'", Conn)

---

Hope that helps.

Cheers,

Ian

Your SQL code is being sent to the database to be executed. The database doesn't know anything about your form so "combobox7.text" has no meaning to it. If you want to use values from your controls and use them in SQL code then you do so using parameters. To learn how, follow the Blog link in my signature and check out my post on Parameters In ADO.NET.

Two others points to note:

1. Don't execute your query twice. As the name suggests, ExecuteNonQuery is for executing non-query statements, i.e. anything other than SELECT. If you want to execute a query then you call ExecuteScalar, ExecuteReader or Fill, depending on the circumstances. To learn what ADO.NET objects to use when, follow the CodeBank link in my signature and check out my thread on Retrieving & Saving Data.

2. When posting code, please wrap it in formatting tags. You can type them yourself or else use the buttons provided on the advanced editor.

Quote:

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Originally Posted by IanRyder

Hi,

Your error is here:-

Code:

---

oleAdapter1 = New OleDb.OleDbDataAdapter("Select * From Table1 where Table1.Location = combobox7.text", Conn)

---

The way you have it now combobox7.text is being interpreted as a parameter since your Table1.Location column is a text field and you have not passed a Text value to the Where clause.

You should look into using parameters correctly rather than using string concatenation, but to solve your issue try this:-

Code:

---

oleAdapter1 = New OleDb.OleDbDataAdapter("Select * From Table1 where Table1.Location = '" & ComboBox7.Text & "'", Conn)

---

Hope that helps.

Cheers,

Ian

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Hey Ian, thanks for the solution it worked!!!

Quote:

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Originally Posted by enigma1810

Hey Ian, thanks for the solution it worked!!!

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That's not a good solution I'm afraid. It will work in some cases but not all and the habit of using string concatenation to insert values into SQL code is not a good one to get into. I strongly recommend using parameters every time. The blog post I directed you to earlier outlines the reasons.