At the top of the filter window are drop downs which relate to the column, the operator and an area where the value can be entered. Clicking the '+' icon will add this clause to the end of the filter.
Filter expressions are very similar to SQL WHERE clauses. You can enter text that refers to column names and uses operators to compare with other columns or static values. Filter expressions also support combinational logic using AND/OR.
[Size] > 50000
[DateModified] BETWEEN '2017/01/01' AND '2017/02/01'
[CustomerName] LIKE 'Fred%' AND [OrderComplete] != 1
!=: Not Equal
<>: Not Equal
>: Greater Than
>=: Greater Than Or Equal To
<: Less Than
<=: Less Than Or Equal To
!>: Not Greater Than
!<: Not Less Than
LIKE: Value matches SQL-style string pattern
NOT LIKE: Value does not match SQL-style string pattern
BETWEEN: Value falls between [x] and [y]
AND/OR can be used to combine expression clauses, and parenthesis can be used to group clauses.
[a] = 5 AND [b] = 2 AND [c] = 9
[a] > 1 AND ([b] > 10 OR [c] > 20)
Static value formatting
Values are formatted as they would be in SQL. Strings, GUIDs and Date/Time values are enclosed in quotes, boolean values are 0 or 1 and numeric values are represented naturally.
String: 'a string'