UX - searching null values in a filtered grid

I have a custom filtered grid where first row for each column is used by end users to search for a particular value in a column. (each row has a text box where user's can enter the value they need to search for) Initially -

• when the grid is loaded on the page, text box in row 1 for each column is empty and data is displayed开发者_运维百科 in the grid.

• user can enter whatever value he wants to search in a particular column and hit enter, this would reload the grid with the correct filtered records.

Issue - How do we allow user to search for null values in a column. Since currently if the textbox in row 1 is empty, we display grid back to default status i.e load all records.

Thanks

1. You could use a reserved keyword, like NULL or NONE or something.
2. Or make the first row a combo box with auto-suggest. The benefits are that the auto-suggest helps to avoid misspellings, but also the very first choice could say "No Value" or synonym.
3. You have an icon or right click as a third choice which allows you to choose "No Value"...this could automatically type in the reserved word to help the user learn that gesture.