[GitHub] [arrow-datafusion] xudong963 commented on issue #1688: Testing result of String related built-in functions

[GitBox <gi...@apache.org>]

xudong963 commented on issue #1688:
URL: https://github.com/apache/arrow-datafusion/issues/1688#issuecomment-1022950128


   About `substr` & `substring`
   
   I believe now datafusion supports `substring` and `select substring("" from x for y)`. BTW the behavior is the same as Postgres.
   ```sql
   ❯ SELECT substring('Spark SQL', -3);
   +-------------------------------------+
   | substr(Utf8("Spark SQL"),Int64(-3)) |
   +-------------------------------------+
   | Spark SQL                           |
   +-------------------------------------+
   1 row in set. Query took 0.006 seconds.
   ❯ SELECT substr('Spark SQL', -3);
   +-------------------------------------+
   | substr(Utf8("Spark SQL"),Int64(-3)) |
   +-------------------------------------+
   | Spark SQL                           |
   +-------------------------------------+
   1 row in set. Query took 0.006 seconds.
   ❯ SELECT substring('Spark SQL' from 5 for 1);
   +---------------------------------------------+
   | substr(Utf8("Spark SQL"),Int64(5),Int64(1)) |
   +---------------------------------------------+
   | k                                           |
   +---------------------------------------------+
   1 row in set. Query took 0.007 seconds.
   ```
   


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