Where That Selects All?

I have a query that I wish to initially call to catch all results from a database. Then, when a combobox is updated, I wish for it to catch the columns only WHERE column = Selected

Solution 1:

Set SelectedItemFromComboBox to null and change your query to

SELECT*FROM Table1
WHERE Column1 = SelectedItemFromComboBox
or SelectedItemFromComboBox isnull

Solution 2:

You can put something like the empty string into SelectedItemFromComboBox and modify your query:

SELECT*FROM Table1
WHERE SelectedItemFromComboBox =''OR Column1 = SelectedItemFromComboBox;

Solution 3:

SELECT*FROM Table1
WHERE Column1 = Column1

will get all the data

so you can use a null value

SELECT*FROM Table1
WHERE Column1 = isnull(some_value, Column1)

where some value is NULL. To do this use an empty string and then this

SELECT*FROM Table1
WHERE Column1 = isnull(CASEWHEN some_value =''thenNULLelse some_value end)), Column1)

and this will return what you want

Solution 4:

In this condition you can set the "SelectedItemFromComboBox" to 0 and update the query in this way so if first condition not match its going for OR condition where 0=0 and returns all records for initial combobox value.

SELECT * FROM Table1

WHERE Column1 = SelectedItemFromComboBox OR 0=SelectedItemFromComboBox ;

Solution 5:

If for some reason you are unable to modify the query and you only have control over the value going in, and you're not using parameterized queries, and you know 100% how to protect against SQL injection, then you can set SelectedItemFromComboBox to '' OR 1 = 1. This should be extremely rare and only be needed if there's bad code that you don't have control over, and is completely a hack.