How to fetch data from access database in a textBox using C#

Question

I have a database in which I created a table HUGO_BOSS. Its columns are [brand name], [stock quantity], [retail price] and its primery key is [Brand name]. I want to fill my textbox in windows form with the value of stock quantity present in my database. I tried the following code but it gives run-time error

The Connection was not close, the connection state is open.

if (comboBox2.Text == "HUGO BOSS")
{
    try
    {
        OleDbCommand cmd = con.CreateCommand();
        cmd.CommandText = "Select [Stock quantity] as stockquantity from HUGO_BOSS WHERE [Brand name]=@name";
        cmd.Parameters.AddWithValue("@name", comboBox3.SelectedItem);
        con.Open();
        OleDbDataReader dr = cmd.ExecuteReader(CommandBehavior.SingleResult);
        if (dr.Read())
        {
            textBox7.Text = dr["stockquantity"].ToString();
        }
    }
    finally { con.Close(); }
}

One more thing, here I will select the primary key by using a combobox3

p.s.w.g · Accepted Answer · 2013-11-29 18:21:43Z

1

It looks you're trying to reuse a database connection that is already open.

You could try testing the connection state before trying to open it:

OleDbCommand cmd = con.CreateCommand();
cmd.CommandText = "Select [Stock quantity] as stockquantity from HUGO_BOSS WHERE [Brand name]=@name";
cmd.Parameters.AddWithValue("@name", comboBox3.SelectedItem);
if (con.State == ConnectionState.Closed)
{
    con.Open();
}
OleDbDataReader dr = cmd.ExecuteReader(CommandBehavior.SingleResult);
if (dr.Read())
{
    textBox7.Text = dr["stockquantity"].ToString();
}

Alternatively, you could create a new connection each time you need to execute a new command.

answered Nov 29, 2013 at 18:21

p.s.w.g

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6 Comments

user3043233 Over a year ago

it gives an error "Multiple-step OLE DB operation generated errors. Check each OLE DB status value, if available. No work was done."

p.s.w.g Over a year ago

@Dany In your question you say the table name is HUGGO_BOSS, but in the SQL code you're querying table HUGO_BOSS (only one G). Are you sure the SQL query is correct? Also, what type is comboBox3.SelectedItem?

user3043233 Over a year ago

sorry, actually there is a typing mistake in question.The correct spelling is HUGO_BOSS and my combobox3 contains the list of brand name from the database. If a users selects a particular brand name, then my textbox should give its quantity available in the stock.

p.s.w.g Over a year ago

@Dany If SelectedItem is a string, are you sure that [Brand Name] in a varchar or nvarchar (or char / nchar)? Also, did you specify the database name in your connection string?

user3043233 Over a year ago

yes i specified the database name in connection string. and my brand name is a text. Actually i am using ms access database.

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