terrymanu commented on issue #28669:
URL:
https://github.com/apache/shardingsphere/issues/28669#issuecomment-3621745403
Problem Understanding
- Running SELECT [Limit1].[AccountID] AS [AccountID] FROM ( SELECT TOP (1)
[AccountID] AS [AccountID] FROM [Account] ) AS [Limit1], null on
ShardingSphere-JDBC (SQLServer) throws SQLParsingException; user expected it to
succeed.
Root Cause
- FROM ... , null is not valid SQL Server syntax; null cannot be a table
source. ShardingSphere’s SQLServer parser enforces SQL Server rules and rightly
errors on an invalid table source—this is expected behavior, not a defect.
Issue Analysis
- Native SQL Server also rejects bare null in the FROM clause (e.g.,
“Incorrect syntax near ','/NULL”).
- ShardingSphere’s SQLParserExecutor.twoPhaseParse validates the SQLServer
dialect and fails during parsing.
- To include a constant row, rewrite the SQL:
- Drop the meaningless , null, keeping only the subquery; or
- Use CROSS JOIN (SELECT NULL AS dummy) AS t to inject a constant row.
- If the SQL is generated by an ORM (EF/LINQ, etc.), adjust the ORM
query/config so it doesn’t emit the invalid , null fragment.
Conclusion
- The observed error comes from invalid SQL input, not a ShardingSphere
bug.
- If you believe this SQL should pass on native SQL Server, please share:
the exact result/error from running it directly on SQL Server (with version),
and the SQL generation path (ORM and configuration) so we can verify any
compatibility gap.
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