Question

I try make search for my site. Example: have field name = city, if city is empty my query looks: SELECT * FROM TABLE WHERE CITY = ALL;

I don’t know how to write: CITY = ALL correct, expression CITY is not null will be complicated because I should be remove =

Answer 1

Try this:

SELECT *
FROM Table 
WHERE @SearchParam IS NULL OR City = @SearchParam 

If his parameter @SearchParam is passed to the query with a NULL value then it will return all the data in the table, otherwise it will search for the cities with this parameter.