On 2022-02-02 08:00:00 +0000, Shaozhong SHI wrote: > regex - Regular Expression For Duplicate Words - Stack Overflow > > Is there any example in Postgres? It's pretty much the same as with other regexp dialects: User word boundaries and a word character class to match any word and then use a backreference to match a duplicate word. All the building blocks are described on https://www.postgresql.org/docs/current/functions-matching.html#FUNCTIONS-POSIX-REGEXP and except for [[:<:]] and [[:>:]] for the word boundaries, they are also pretty standard. So [[:<:]] start of word ([[:alpha:]]+) one or more alphabetic characters in a capturing group [[:>:]] end of word \W+ one or more non-word characters [[:<:]] start of word \1 the content of the first (and only) capturing group [[:>:]] end of word All together: select * from t where t ~ '[[:<:]]([[:alpha:]]+)[[:>:]]\W[[:<:]]\1[[:>:]]'; hp -- _ | Peter J. Holzer | Story must make more sense than reality. |_|_) | | | | | hjp@xxxxxx | -- Charles Stross, "Creative writing __/ | http://www.hjp.at/ | challenge!"
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