Non-Spatial Queries#
Manual selection#
Select the features manually in the attribute table by clicking on it.
Example: Manually select countries with the attribute table
Select by expression#
Comparison operators#
>
,<
,=
,!=
Example: Select all cities with more than 20 million inhabitants in 2015: "2015" > 20000
Special operators#
LIKE
Example: Select all countries in Asia: "continent" LIKE 'asia'
Logical operators#
AND
,OR
Can be used to combine different queries or criteria.
Example: Cities, not having a population of one million inhabitants in 1950, had surged to over 10 million inhabitants by 2015: "1950" < 1000 AND "2015" > 10000
Save selected features as a new file#
Layer-Properties
->Export
->Save only selected features
Example: Export selected features as a new file
Further resources#
You can access information about logical operators in QGIS documentation through the following link.
Select by expression options#
operator |
functionality |
---|---|
+ |
addition |
- |
substraction |
* |
multiplication |
/ |
division |
% |
remainder of division |
operator |
functionality |
---|---|
= |
equals |
!= |
not equal |
< |
less than |
> |
greater than |
<= |
less than or equal to |
>= |
greater than or equal to |
Operators such as AND, OR can be used to combine different queris or criteria
operator |
functionality |
---|---|
AND |
logical AND |
OR |
logical OR |
NOT |
logical NOT |
operator |
functionality |
---|---|
LIKE |
pattern matching |
IN |
checks if a value is in a list of values |
IS NULL |
checks for null values |
BETWEEN |
checks if a value is within a specified range |
CASE WHEN |
conditional expressions |