Using QGIS query builder

Question

I have only basic knowledge of using SQL code in QGIS. I am trying to use Query Builder to hide some specific line features. I have tried using =! and the id field reference for the particular features I want to hide but this results in zero features being selected. The column is text. I have tried creating a new column as text and identifying the fields I want as 'yes'and then writing a query identifying those fields not yes. I then did the same but this time as a integer but this doesn't work. Can anyone help. I'm sure its a simple task to do. Interestingly the text fields are all blank rather than null. How do you select a field that is empty

Answer 1

The 'not equal to' operator in SQL is '<>' so you need to use:

OBJECTID <> 1

To select null fields you use:

IS NULL

To select text fields that are empty but not null try selecting an empty string '' or a string with a space ' ':

TextField = ''

TextField = ' '