Fix transform query for external databases in presense of aliases #12032

src/Interpreters/JoinToSubqueryTransformVisitor.cpp

@@ -257,7 +257,7 @@ struct ColumnAliasesMatcher
             if (!last_table)
             {
                 IdentifierSemantic::coverName(node, alias);
-                node.setAlias("");
+                node.setAlias({});
             }
         }
         else if (node.compound())

src/Interpreters/PredicateRewriteVisitor.cpp

@@ -76,7 +76,7 @@ static void cleanAliasAndCollectIdentifiers(ASTPtr & predicate, std::vector<ASTI
     }
 
     if (const auto alias = predicate->tryGetAlias(); !alias.empty())
-        predicate->setAlias("");
+        predicate->setAlias({});
 
     if (ASTIdentifier * identifier = predicate->as<ASTIdentifier>())
         identifiers.emplace_back(identifier);

src/Storages/tests/gtest_transform_query_for_external_database.cpp

@@ -5,6 +5,7 @@
 #include <Parsers/parseQuery.h>
 #include <DataTypes/DataTypesNumber.h>
 #include <DataTypes/DataTypeDateTime.h>
+#include <DataTypes/DataTypeString.h>
 #include <Interpreters/Context.h>
 #include <Databases/DatabaseMemory.h>
 #include <Storages/StorageMemory.h>
@@ -27,6 +28,8 @@ struct State
         {"apply_type", std::make_shared<DataTypeUInt8>()},
         {"apply_status", std::make_shared<DataTypeUInt8>()},
         {"create_time", std::make_shared<DataTypeDateTime>()},
+        {"field", std::make_shared<DataTypeString>()},
+        {"value", std::make_shared<DataTypeString>()},
     };
 
     static const State & instance()
@@ -117,3 +120,12 @@ TEST(TransformQueryForExternalDatabase, Issue7245)
           R"(SELECT "apply_id", "apply_type", "apply_status", "create_time" FROM "test"."table" WHERE ("apply_type" = 2) AND ("create_time" > '2018-12-25 01:02:03') AND ("apply_status" IN (3, 4)))",
           state.context, state.columns);
 }
+
+TEST(TransformQueryForExternalDatabase, Aliases)
+{
+    const State & state = State::instance();
+
+    check("SELECT field AS value, field AS display WHERE field NOT IN ('') AND display LIKE '%test%'",
+          R"(SELECT "field" FROM "test"."table" WHERE ("field" NOT IN ('')) AND ("field" LIKE '%test%'))",
+          state.context, state.columns);
+}

src/Storages/transformQueryForExternalDatabase.cpp

@@ -71,6 +71,24 @@ public:
     }
 };
 
+class DropAliasesMatcher
+{
+public:
+    struct Data {};
+    Data data;
+
+    static bool needChildVisit(ASTPtr &, const ASTPtr &)
+    {
+        return true;
+    }
+
+    static void visit(ASTPtr & node, Data)
+    {
+        if (!node->tryGetAlias().empty())
+            node->setAlias({});
+    }
+};
+
 void replaceConstantExpressions(ASTPtr & node, const Context & context, const NamesAndTypesList & all_columns)
 {
     auto syntax_result = SyntaxAnalyzer(context).analyze(node, all_columns);
@@ -80,6 +98,13 @@ void replaceConstantExpressions(ASTPtr & node, const Context & context, const Na
     visitor.visit(node);
 }
 
+void dropAliases(ASTPtr & node)
+{
+    DropAliasesMatcher::Data data;
+    InDepthNodeVisitor<DropAliasesMatcher, true> visitor(data);
+    visitor.visit(node);
+}
+
 
 bool isCompatible(const IAST & node)
 {
@@ -192,6 +217,9 @@ String transformQueryForExternalDatabase(
         }
     }
 
+    ASTPtr select_ptr = select;
+    dropAliases(select_ptr);
+
     std::stringstream out;
     IAST::FormatSettings settings(out, true);
     settings.identifier_quoting_style = identifier_quoting_style;