[GitHub] [shardingsphere] fangs95 commented on issue #24207: java.sql.SQLFeatureNotSupportedException: can't get index from columnLabel[xxxxxxxxx]

["fangs95 (via GitHub)" <gi...@apache.org>]

fangs95 commented on issue #24207:
URL: https://github.com/apache/shardingsphere/issues/24207#issuecomment-1579047451

   This problem is due to the use of expressions in the select clause. It should be because this is a framework for data shard that the expressions in select are disabled.
   org.apache.shardingsphere.infra.binder.segment.select.projection.engine.ProjectionEngine#getColumnProjections
   ```java
       private Collection<ColumnProjection> getColumnProjections(final Collection<Projection> projections) {
           Collection<ColumnProjection> result = new LinkedList<>();
           for (Projection each : projections) {
               if (each instanceof ColumnProjection) {
                   result.add((ColumnProjection) each);
               }
               if (each instanceof ShorthandProjection) {
                   result.addAll(((ShorthandProjection) each).getActualColumns().values());
               }
           }
           return result;
       }
   ```
   This code will filter out the ExpressionProjection.
   
   Because I only use read-write separation, I override this method in my own project.
   ```java
       private Collection<ColumnProjection> getColumnProjections(final Collection<Projection> projections) {
           Collection<ColumnProjection> result = new LinkedList<>();
           int mockSeq = 0;
           for (Projection each : projections) {
               if (each instanceof ColumnProjection) {
                   result.add((ColumnProjection) each);
               }
               if (each instanceof ExpressionProjection) {
                   ExpressionProjection expressionProjection = (ExpressionProjection) each;
                   ColumnProjection projection = new ColumnProjection(null, "mock" + mockSeq++, expressionProjection.getAlias().get());
                   result.add(projection);
               }
               if (each instanceof ShorthandProjection) {
                   result.addAll(((ShorthandProjection) each).getActualColumns().values());
               }
           }
           return result;
       }
   ```
   I just don't know if changing this will cause other problems


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