regex101: PCRE (Legacy) Match Workspace

Group 1(["'])

Character Class["']

"the literal " (34₁₀ / 42₈ / 22₁₆)

'the literal ' (39₁₀ / 47₈ / 27₁₆)

\s*any whitespace character, repeated any number of times

Group 2(SELECT)

SELECTthe literal text SELECT (case sensitive)

Non-Capturing Group(?:\s+.*)?

?repeats the group contents below at most once:

\s+any whitespace character, repeated at least once

.*any character (except for line terminators), repeated any number of times

\s+any whitespace character, repeated at least once

Group 3(FROM)

FROMthe literal text FROM (case sensitive)

Non-Capturing Group(?:\s+.*)?

?repeats the group contents below at most once:

\s+any whitespace character, repeated at least once

.*any character (except for line terminators), repeated any number of times

\1the text saved by group 1

Non-Capturing Group(?:[^\w]|$)

1st Alternative[^\w]

Negated Character Class[^\w]

\wany word character

2nd Alternative$

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

(["'])\s*(SELECT)(?:\s+.*)?\s+(FROM)(?:\s+.*)?\1(?:[^\w]|$)

New

    SELECT * FROM tbl        -- no match - not in a string
    "SELECT * FROM tbl"      -- matches - in a double-quoted string
    'SELECT * FROM tbl;'     -- matches - in a single-quoted string
    'SELECT * FROM it's      -- no match - letter after end quote
    "SELECT * FROM tbl'      -- no match - quotation marks don't match
    'SELECT * FROM tbl"      -- no match - quotation marks don't match
    "select * from tbl"      -- no match - keywords not upper case
    'Select * From tbl'      -- no match - still not all upper case
    "SELECT col1 FROM"       -- matches - even though no table name
    '  SELECT  col1  FROM '  -- matches - as above with more whitespace
    'SELECT col1, col2 FROM' -- matches - with multiple columns