fix: add distinctClause transformation to SelectStmt and improve ColumnRef String field handling

Co-Authored-By: Dan Lynch <[email protected]>

Author: devin-ai-integration[bot]

packages/transform/src/transformers/v14-to-v15.ts

@@ -199,7 +199,12 @@ export class V14ToV15Transformer extends BaseTransformer {
     const transformedData = { ...node };
 
     if (transformedData.fields && Array.isArray(transformedData.fields)) {
-      transformedData.fields = transformedData.fields.map((field: any) => this.transform(field, context));
+      transformedData.fields = transformedData.fields.map((field: any) => {
+        if (field && typeof field === 'object') {
+          return this.transform(field, context);
+        }
+        return field;
+      });
     }
 
     return transformedData;
@@ -248,6 +253,10 @@ export class V14ToV15Transformer extends BaseTransformer {
       }
     }
 
+    if (transformedData.distinctClause && Array.isArray(transformedData.distinctClause)) {
+      transformedData.distinctClause = transformedData.distinctClause.map((item: any) => this.transform(item, context));
+    }
+    
     if (transformedData.withClause && typeof transformedData.withClause === 'object') {
       transformedData.withClause = { ...transformedData.withClause };
       if (transformedData.withClause.ctes && Array.isArray(transformedData.withClause.ctes)) {