NOT LIKE

SELECT
    f1 := 'hello' NOT LIKE 'world', -- No match
    f2 := 'hello' NOT LIKE 'h%', -- Does start with 'h'
    f3 := 'hello' NOT LIKE '%o', -- Does end with 'o'
    f4 := 'hello' NOT LIKE '%ll%', -- Does contain 'll'
    f5 := 'hello' NOT LIKE 'h_llo', -- Does match pattern
    f6 := 'hello' NOT LIKE 'HELLO' -- Case sensitive
;

SELECT
    f1 := NULL::VARCHAR NOT LIKE 'pattern', -- NULL string
    f2 := 'text' NOT LIKE NULL::VARCHAR -- NULL pattern
;

SELECT
    f1 := 'document.pdf' NOT LIKE '%.txt', -- Not a text file
    f2 := 'data.csv' NOT LIKE '%.txt' -- Not a text file
;