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Editorial Team
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Asked: 2026-05-23T08:16:25+00:00

I’m designing a C# program using .NET and Windows Forms. At one point I

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I’m designing a C# program using .NET and Windows Forms. At one point I need to open a form that contains a DataGridView object and a TextBox. The DataGridView object is to be fed with the input on the TextBox and show real-time matches from the database.

To accomplish this, I’ve been using the simple SQL Query that follows:

SqlCommand cmd = "SELECT name,document_no FROM clients WHERE LEFT(name, " + textboxname.Text.Len + ") = '" textboxname.Text + "'";

It works for now, while my database contains about a dozen of rows, but is it efficient for large-sized (2k+ entries) databases?

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  1. Editorial Team

    The approach you’re taking won’t be efficient – at least, not if there’s an index on the name column (if there is no such index then expect poor performance whatever you do). Typically, any function called in a WHERE clause where one or more of the parameters are columns is going to defeat any attempts of the query optimizer to use indexes on those columns.

    Much better is:

    SELECT name,document_no FROM clients WHERE name LIKE 'yourtextboxtexthere%'

    …which will have a good chance of using the index on name.

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