NOT LIKE

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

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

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