Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A single character of: a, b, c or d
    [[ab][cd]]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Character class intersection
    [\w&&[^\d]]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

"
"
mg

Test String

Code Generator

Language

Generated Code

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r"select\s+(\*|((\w+(\.\w+)?)+(\s?,\s?\w+(\.\w+)?)*)|((\w+\([^\s]|(\w+\.\w+)?\))(\s+\,\s+)?)+)\s+from\s+(\w+(\s?,\s?\w+)*\;?)(\s+((\w+\s+join)\s+(\w+(\.\w)?\s+on\s+(\w+(\.\w+)?\s+=\s+\w+(\.\w+)?)?)(\s+,\s+)?)+)?(\s+((limit\s+(\w+)?\s?(\,\w+\;)?)|((where)?\s+?([^\;]+\s?;))))?" test_str = ("select * from table4;\n" "select * from table4,table5;\n" "select table4.id from table4,table5;\n" "select table4.id from table4,table5 where table4.id=table5.id;\n" "select * from table4,table5 where table4.id=table5.id;\n" "select * from table4,table5 where table4.id=table5.id and table4.id => 1 ;\n" "select table4.id,table5.name from table4,table5 where table4.id=table5.id and table4.id>1 ;\n" "select table4.id from table4,table5 where table4.id=table5.id like %ll%;\n" "select table4.id from table4,table5 where table4.id=table5.id limit 1,10;\n" "select table4.id from table4,table5 limit 1,10;\n" "select table4.id from table4,table5 limit 1 ;\n" "select table4.id from table4,table5 where id <> 1 limit 1 ;\n" "select count(*) from table4,table5 where id <> 1 limit 1 ;\n" "select count(*) from table4,table5 where id <> 1 having dd group by dd ;\n" "select count(*) , max(table4.id) from table4,table5 where id <> 1 having dd group by dd ;\n" "select * from tab1 left join tab2 on tab1.size = tab2.size where tab2.name = AAA;\n" "select * from tab1 left join tab2 on tab1.size = tab2.size , right join tab2 on tab1.size = tab2.size where tab2.name = AAA and dd = dd;\n" "select count(*) , max(table4.id) from table4,table5 left join tab2 on tab1.size = tab2.size , right join tab2 on tab1.size = tab2.size where id <> 1 having dd group by dd ;\n") matches = re.finditer(regex, test_str, re.MULTILINE) for matchNum, match in enumerate(matches, start=1): print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group())) for groupNum in range(0, len(match.groups())): groupNum = groupNum + 1 print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum))) # Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Python, please visit: https://docs.python.org/3/library/re.html