Primary key

Dear Experts
How to apply primary key on sno column in the following dataset

Code:

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  dim sql = "select * from employees"
        Dim da As new SqlClient.SqlDataAdapter (sql,con)
        'ds.Clear()
        da.Fill(ds, "employees")
        TextBox1.DataBindings.Add("text", ds.Tables("employees"), "sno")
        TextBox2.DataBindings.Add("text", ds.Tables("employees"), "Name")
        TextBox3.DataBindings.Add("text", ds.Tables("employees"), "City")
        TextBox4.DataBindings.Add("text", ds.Tables("employees"), "Phone")

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Please help

Normally, that would be done at the DataBase (when it was built).

Table employees has primary key on sno column, but when i use these codes it says there is no primary key.

Code:

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Me.ds.Tables("employees").Rows.Find(Me.TextBox1.Text)
        Me.BindingContext(ds.Tables("employees")).Position += 1

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