liancheng commented on issue #24840: [SPARK-27998][SQL] Column alias should support quote string URL: https://github.com/apache/spark/pull/24840#issuecomment-500952463 @lipzhu ANSI SQL uses double quotes to quote identifiers with special characters. Basically, double-quotes in ANSI SQL is equivalent to backquotes in Spark SQL while ANSI SQL single-quotes are for string literals. That being said, I don't think ANSI SQL ever allows *string literals* to be used as aliases. It has to be an identifier. The SQL '03 [grammar rule][1] also suggests that. In the future, if we have something like "SQL dialect profile" that allows users to switch between different dialect and use double-quotes for quoting identifiers and single-quotes for quoting strings, then we can have this syntax. But right now, the syntax change proposed in this PR is inconsistent and violate ANSI SQL. [1]: https://ronsavage.github.io/SQL/sql-2003-2.bnf.html#as%20clause
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