Extracting numbers from text attribute in QGIS

Question

Is it possible to make a new column and store only the numbers in the column "GNR" i.e. removing (1: ))?

Answer 1

With a proper regexp term using the regexp_substr() function:

 to_int( regexp_substr( "GNR", ':([^)]+)\)' ) )

that retrieves all characters between : & ) like so:

• :: match sequence must start with this character
• (: start retrieving sub-string
• [^)]+: collect all characters that are not )
• ): end retrieving sub-string
• \): match sequence must end with this character (escaped because ) is a meta character)

Answer 2

Use one of these expressions:

replace (replace (GNR, '(1:',''),')','')

left (substr( GNR,4),length('GNR')-1)