Replace syntax "DEFAULT DATABASE ''" with "DEFAULT DATABASE NONE".

Show default database in system.users.

Author: Vitaly Baranov

src/Access/User.cpp

@@ -11,7 +11,7 @@ bool User::equal(const IAccessEntity & other) const
     const auto & other_user = typeid_cast<const User &>(other);
     return (authentication == other_user.authentication) && (allowed_client_hosts == other_user.allowed_client_hosts)
         && (access == other_user.access) && (granted_roles == other_user.granted_roles) && (default_roles == other_user.default_roles)
-        && (settings == other_user.settings) && (grantees == other_user.grantees);
+        && (settings == other_user.settings) && (grantees == other_user.grantees) && (default_database == other_user.default_database);
 }
 
 }

src/Access/UsersConfigAccessStorage.cpp

@@ -196,8 +196,7 @@ namespace
             user->access.revokeGrantOption(AccessType::ALL);
         }
 
-        String default_database = config.getString(user_config + ".default_database", "");
-        user->default_database = default_database;
+        user->default_database = config.getString(user_config + ".default_database", "");
 
         return user;
     }

src/Interpreters/InterpreterCreateUserQuery.cpp

@@ -59,8 +59,8 @@ namespace
         else if (query.default_roles)
             set_default_roles(*query.default_roles);
 
-        if (!query.default_database.empty())
-            user.default_database = query.default_database;
+        if (query.default_database)
+            user.default_database = *query.default_database;
 
         if (override_settings)
             user.settings = *override_settings;

src/Interpreters/InterpreterShowCreateAccessEntityQuery.cpp

@@ -82,7 +82,8 @@ namespace
             query->grantees->use_keyword_any = true;
         }
 
-        query->default_database = user.default_database;
+        if (!user.default_database.empty())
+            query->default_database = user.default_database;
 
         return query;
     }

src/Parsers/ASTCreateUserQuery.cpp

@@ -213,7 +213,11 @@ namespace
 
     void formatDefaultDatabase(const String & default_database, const IAST::FormatSettings & settings)
     {
-        settings.ostr << (settings.hilite ? IAST::hilite_keyword : "") << " DEFAULT DATABASE " << (settings.hilite ? IAST::hilite_none : "") << default_database;
+        settings.ostr << (settings.hilite ? IAST::hilite_keyword : "") << " DEFAULT DATABASE " << (settings.hilite ? IAST::hilite_none : "");
+        if (default_database.empty())
+            settings.ostr << (settings.hilite ? IAST::hilite_keyword : "") << "NONE" << (settings.hilite ? IAST::hilite_none : "");
+        else
+            settings.ostr << backQuoteIfNeed(default_database);
     }
 }
 
@@ -267,8 +271,8 @@ void ASTCreateUserQuery::formatImpl(const FormatSettings & format, FormatState &
     if (remove_hosts)
         formatHosts("DROP", *remove_hosts, format);
 
-    if (!default_database.empty())
-        formatDefaultDatabase(default_database, format);
+    if (default_database)
+        formatDefaultDatabase(*default_database, format);
 
     if (default_roles)
         formatDefaultRoles(*default_roles, format);

src/Parsers/ASTCreateUserQuery.h

@@ -53,7 +53,7 @@ class ASTCreateUserQuery : public IAST, public ASTQueryWithOnCluster
     std::shared_ptr<ASTSettingsProfileElements> settings;
     std::shared_ptr<ASTRolesOrUsersSet> grantees;
 
-    String default_database;
+    std::optional<String> default_database;
 
     String getID(char) const override;
     ASTPtr clone() const override;

src/Parsers/ParserCreateUserQuery.cpp

@@ -301,14 +301,24 @@ namespace
         });
     }
 
-    bool parseDefaultDatabase(IParserBase::Pos & pos, Expected & expected, String & default_database)
+    bool parseDefaultDatabase(IParserBase::Pos & pos, Expected & expected, std::optional<String> & default_database)
     {
         return IParserBase::wrapParseImpl(pos, [&]
         {
             if (!ParserKeyword{"DEFAULT DATABASE"}.ignore(pos, expected))
                 return false;
 
-            return parseIdentifierOrStringLiteral(pos, expected, default_database);
+            if (ParserKeyword{"NONE"}.ignore(pos, expected))
+            {
+                default_database = "";
+                return true;
+            }
+
+            String db_name;
+            if (!parseIdentifierOrStringLiteral(pos, expected, db_name))
+                return false;
+            default_database = db_name;
+            return true;
         });
     }
 }
@@ -360,8 +370,8 @@ bool ParserCreateUserQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expec
     std::shared_ptr<ASTRolesOrUsersSet> default_roles;
     std::shared_ptr<ASTSettingsProfileElements> settings;
     std::shared_ptr<ASTRolesOrUsersSet> grantees;
+    std::optional<String> default_database;
     String cluster;
-    String default_database;
 
     while (true)
     {
@@ -402,7 +412,7 @@ bool ParserCreateUserQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expec
         if (!grantees && parseGrantees(pos, expected, attach_mode, grantees))
             continue;
 
-        if (default_database.empty() && parseDefaultDatabase(pos, expected, default_database))
+        if (!default_database && parseDefaultDatabase(pos, expected, default_database))
             continue;
 
         if (alter)

src/Storages/System/StorageSystemUsers.cpp

@@ -50,6 +50,7 @@ NamesAndTypesList StorageSystemUsers::getNamesAndTypes()
         {"grantees_any", std::make_shared<DataTypeUInt8>()},
         {"grantees_list", std::make_shared<DataTypeArray>(std::make_shared<DataTypeString>())},
         {"grantees_except", std::make_shared<DataTypeArray>(std::make_shared<DataTypeString>())},
+        {"default_database", std::make_shared<DataTypeString>()},
     };
     return names_and_types;
 }
@@ -85,14 +86,16 @@ void StorageSystemUsers::fillData(MutableColumns & res_columns, ContextPtr conte
     auto & column_grantees_list_offsets = assert_cast<ColumnArray &>(*res_columns[column_index++]).getOffsets();
     auto & column_grantees_except = assert_cast<ColumnString &>(assert_cast<ColumnArray &>(*res_columns[column_index]).getData());
     auto & column_grantees_except_offsets = assert_cast<ColumnArray &>(*res_columns[column_index++]).getOffsets();
+    auto & column_default_database = assert_cast<ColumnString &>(*res_columns[column_index++]);
 
     auto add_row = [&](const String & name,
                        const UUID & id,
                        const String & storage_name,
                        const Authentication & authentication,
                        const AllowedClientHosts & allowed_hosts,
                        const RolesOrUsersSet & default_roles,
-                       const RolesOrUsersSet & grantees)
+                       const RolesOrUsersSet & grantees,
+                       const String & default_database)
     {
         column_name.insertData(name.data(), name.length());
         column_id.push_back(id.toUnderType());
@@ -180,6 +183,8 @@ void StorageSystemUsers::fillData(MutableColumns & res_columns, ContextPtr conte
         for (const auto & except_name : grantees_ast->except_names)
             column_grantees_except.insertData(except_name.data(), except_name.length());
         column_grantees_except_offsets.push_back(column_grantees_except.size());
+
+        column_default_database.insertData(default_database.data(), default_database.length());
     };
 
     for (const auto & id : ids)
@@ -192,7 +197,7 @@ void StorageSystemUsers::fillData(MutableColumns & res_columns, ContextPtr conte
         if (!storage)
             continue;
 
-        add_row(user->getName(), id, storage->getStorageName(), user->authentication, user->allowed_client_hosts, user->default_roles, user->grantees);
+        add_row(user->getName(), id, storage->getStorageName(), user->authentication, user->allowed_client_hosts, user->default_roles, user->grantees, user->default_database);
     }
 }