fix(kingbase): quote MySQL-compatible identifiers

agents/common/src/main/java/com/dbx/agent/AbstractJdbcAgent.java

@@ -20,6 +20,16 @@ public abstract class AbstractJdbcAgent extends BaseDatabaseAgent {
         return connection;
     }
 
+    @Override
+    public String getIdentifierQuote() {
+        try {
+            String quote = requireConnected().getMetaData().getIdentifierQuoteString();
+            return quote == null || quote.trim().isEmpty() ? "" : quote.trim();
+        } catch (Exception ignored) {
+            return "";
+        }
+    }
+
     @Override
     public final void connect(ConnectParams params) {
         uncheckedVoid(() -> {

agents/common/src/main/java/com/dbx/agent/AgentProtocol.java

@@ -16,6 +16,7 @@ public final class AgentProtocol {
     public static final String METHOD_CANCEL_SESSION = "cancel_session";
     public static final String METHOD_TEST_CONNECTION = "test_connection";
     public static final String METHOD_VALIDATE_CONNECTION = "validate_connection";
+    public static final String METHOD_CONNECTION_INFO = "connection_info";
     public static final String METHOD_LIST_DATABASES = "list_databases";
     public static final String METHOD_LIST_SCHEMAS = "list_schemas";
     public static final String METHOD_LIST_TABLES = "list_tables";
@@ -100,6 +101,7 @@ public final class AgentProtocol {
         METHOD_CONNECT,
         METHOD_TEST_CONNECTION,
         METHOD_VALIDATE_CONNECTION,
+        METHOD_CONNECTION_INFO,
         METHOD_LIST_DATABASES,
         METHOD_LIST_SCHEMAS,
         METHOD_LIST_TABLES,

agents/common/src/main/java/com/dbx/agent/DatabaseAgent.java

@@ -13,6 +13,10 @@ public interface DatabaseAgent {
 
     boolean testConnection(ConnectParams params);
 
+    default String getIdentifierQuote() {
+        return "";
+    }
+
     List<DatabaseInfo> listDatabases();
 
     List<String> listSchemas();

agents/common/src/main/java/com/dbx/agent/JsonRpcServer.java

@@ -125,6 +125,9 @@ public final class JsonRpcServer {
             return Collections.singletonMap("ok", true);
         }
         ensureLiveConnection(method);
+        if (AgentProtocol.METHOD_CONNECTION_INFO.equals(method)) {
+            return Collections.singletonMap("identifierQuote", agent.getIdentifierQuote());
+        }
         if (AgentProtocol.METHOD_LIST_DATABASES.equals(method)) {
             return agent.listDatabases();
         }

agents/common/src/main/java/com/dbx/agent/PostgresLikeAgent.java

@@ -28,6 +28,11 @@ public abstract class PostgresLikeAgent extends AbstractJdbcAgent {
         return mysqlCompatMode;
     }
 
+    @Override
+    public String getIdentifierQuote() {
+        return mysqlCompatMode ? "`" : super.getIdentifierQuote();
+    }
+
     @Override
     public QueryResult executeQuery(String sql, String schema, ExecuteQueryOptions options) {
         return JdbcExecutor.current().execute(

agents/common/src/main/resources/agent-protocol-v1.json

@@ -39,6 +39,7 @@
     "connect",
     "test_connection",
     "validate_connection",
+    "connection_info",
     "list_databases",
     "list_schemas",
     "list_tables",

agents/common/src/main/resources/agent-protocol-v2.json

@@ -46,6 +46,7 @@
     "cancel_session",
     "test_connection",
     "validate_connection",
+    "connection_info",
     "list_databases",
     "list_schemas",
     "list_tables",