Regular Expressions 101

1st Alternative(?:\w+\s+){1,2}(?=inner|outer join)

Non-Capturing Group(?:\w+\s+){1,2}

{1,2}repeats the group contents below between 1 and 2 times:

\w+any word character, repeated at least once

\s+any whitespace character, repeated at least once

Positive Lookahead(?=inner|outer join)

1st Alternativeinner

innerthe literal text inner (case sensitive)

2nd Alternativeouter join

outer jointhe literal text outer join (case sensitive)

2nd Alternative(?<=inner join)(?:\s+\w+){1,2}

Positive Lookbehind(?<=inner join)

inner jointhe literal text inner join (case sensitive)

Non-Capturing Group(?:\s+\w+){1,2}

{1,2}repeats the group contents below between 1 and 2 times:

\s+any whitespace character, repeated at least once

\w+any word character, repeated at least once

3rd Alternative(?<=outer join)(?:\s+\w+){1,2}

Positive Lookbehind(?<=outer join)

outer jointhe literal text outer join (case sensitive)

Non-Capturing Group(?:\s+\w+){1,2}

{1,2}repeats the group contents below between 1 and 2 times:

\s+any whitespace character, repeated at least once

\w+any word character, repeated at least once

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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(?:\w+\s+){1,2}(?=inner|outer join)|(?<=inner join)(?:\s+\w+){1,2}|(?<=outer join)(?:\s+\w+){1,2}

New

table1 t1 inner join table2 t2 outer join table3
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table1 t1 inner join table2 t2 outer join table3 t3 inner join table2