If in your project you want to include only certain rows in the display you can use a DataView to apply custom filtering. To accomplish this, you should use the RowFilter property which acts like a WHERE clause in a SQL query. You can limit the final results by using it and by applying logical operators, described in the next table:
| Operator | Description |
| <, >, <=, and >= | Performs comparison of more than one value. These comparisons can be numeric (with number data types) or alphabetic dictionary comparisons (with string data types). |
| <> and = | Performs equality testing. |
| NOT | Reverses an expression. Can be used in conjunction with any other clause. |
| BETWEEN | Specifies an inclusive range. For example, “Units BETWEEN 5 AND 15” selects rows that have a value in the Units column from 5 to 15. |
| IS NULL | Tests the column for a null value. |
| IN(a,b,c) | A short form for using an OR clause with the same field. Tests for equality between a column and the specified values (a, b, and c). |
| LIKE | Performs pattern matching with string data types. |
| + | Adds two numeric values or concatenates a string. |
| – | Subtracts one numeric value from another. |
| * | Multiplies two numeric values. |
| / | Divides one numeric value by another. |
| % | Finds the modulus (the remainder after one number is divided by another). |
| AND | Combines more than one clause. Records must match all criteria to be displayed. |
| OR | Combines more than one clause. Records must match at least one of the filter expressions to be displayed. |
The next example page includes three GridView controls. Each one is bound to the same DataTable but with different filter settings:
// Step 1. Retrieve the data into a DataSet
// Create the Connection, DataAdapter, and DataSet.
string connectionString = WebConfigurationManager.ConnectionStrings[“SomeCompany”].ConnectionString;
SqlConnection con = new SqlConnection(connectionString);
string sql = “SELECT ProductID, ProductName, UnitsInStock, UnitsOnOrder, Discontinued FROM Products”;
SqlDataAdapter da = new SqlDataAdapter(sql, con);
DataSet ds = new DataSet();
da.Fill(ds, “Products”);
//Step 2. Filter each DataView for different criterion
// Filter for the Computer product
DataView view1 = new DataView(ds.Tables[“Products”]);
view1.RowFilter = “ProductName = ‘Computer'”;
grid1.DataSource = view1;
// Filter for products that aren’t on order or in stock.
DataView view2 = new DataView(ds.Tables[“Products”]);
view2.RowFilter = “UnitsInStock = 0 AND UnitsOnOrder = 0”;
grid2.DataSource = view2;
// Filter for products starting with the letter K.
DataView view3 = new DataView(ds.Tables[“Products”]);
view3.RowFilter = “ProductName LIKE ‘K%'”;
grid3.DataSource = view3;
//Step 3. Copy the values form the DataTable into control separately or for entire page by calling Page.DataBind().
Page.DataBind();
