[GitHub] [arrow-datafusion] Jefffrey commented on issue #5187: Dataframe API adds ?table? qualifier

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

Jefffrey commented on issue #5187:
URL: https://github.com/apache/arrow-datafusion/issues/5187#issuecomment-1420422685

   This seems to be expected behaviour. A Dataframe has a default name of `?table?` if none is specified:
   
   https://github.com/apache/arrow-datafusion/blob/48732b4cb2c8e42fbe5be295429bbc465e5f5491/datafusion/expr/src/logical_plan/builder.rs#L52
   
   In the error in the original issue post, it is due to you attempting to select the column `last_modified` whereas the correct name is `last_modified_date`
   
   For the error in the subsequent comment, it is because you need to quote the identifiers like so:
   
   ```rust
   let df = df.select(vec![
           col("\"?table?\".key").alias("key"),
           col("\"?table?\".size").alias("size"),
           col("\"?table?\".last_modified").alias("last_modified"),
       ])?;
   ```
   
   Otherwise the parser will assume the entire string is the name of the column, instead of being able to detect there are two identifiers delimited by the period (where first identifier is quoted by double quotes `"`).


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