[GitHub] [arrow-datafusion] comphead commented on issue #6543: Support columns having the same alias

["comphead (via GitHub)" <gi...@apache.org>]

comphead commented on issue #6543:
URL: https://github.com/apache/arrow-datafusion/issues/6543#issuecomment-1633142650

   > 🤯 I didn't realize this worked
   > 
   > ```sql
   > (arrow_dev) alamb@MacBook-Pro-8:~/Software/influxdb_iox2$ datafusion-cli
   > DataFusion CLI v26.0.0
   > ❯ create table foo (x int) as values (1), (2), (3);
   > 0 rows in set. Query took 0.003 seconds.
   > ❯ select x as "my_col", x as "my col" from foo;
   > +--------+--------+
   > | my_col | my col |
   > +--------+--------+
   > | 1      | 1      |
   > | 2      | 2      |
   > | 3      | 3      |
   > +--------+--------+
   > 3 rows in set. Query took 0.005 seconds.
   > ❯ select x as "my_col", x+1 as "my col" from foo;
   > +--------+--------+
   > | my_col | my col |
   > +--------+--------+
   > | 1      | 2      |
   > | 2      | 3      |
   > | 3      | 4      |
   > ```
   > 
   > However, using `c1` as the alias for some reason fails:
   > 
   > ```sql
   > ❯ select x as c1, x as c1 from foo;
   > Error during planning: Projections require unique expression names but the expression "foo.x AS c1" at position 0 and "foo.x AS c1" at position 1 have the same name. Consider aliasing ("AS") one of them.+--------+--------+
   > ```
   
   its failed as DF has projection uniqueness column name check.
   first test didn't fail because it has different aliases


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