fix(gaussdb): support M-mode type metadata

apps/desktop/src/lib/table/postgresDataTypeHelp.ts

@@ -153,3 +153,26 @@ function floatHelpKey(normalizedType: string): "real" | "double" | undefined {
   if (value >= 1 && value <= 24) return "real";
   return value >= 25 && value <= 53 ? "double" : undefined;
 }
+
+/**
+ * Converts a GaussDB M-mode PostgreSQL internal type name to its MySQL-style
+ * display name. Returns the original name if no conversion applies.
+ *
+ * GaussDB M mode returns PostgreSQL internal type names (e.g. bpchar, int4,
+ * numeric, int1) but should display MySQL-compatible names.
+ */
+export function gaussdbMTypeDisplayName(typeName: string): string {
+  const s = typeName.trim().toLowerCase();
+  if (s === "bpchar") return "char";
+  if (s === "int4" || s === "integer") return "int";
+  if (s === "int2" || s === "smallint") return "smallint";
+  if (s === "int8" || s === "bigint") return "bigint";
+  if (s === "int1") return "tinyint";
+  if (s === "numeric") return "decimal";
+  if (s === "float4" || s === "real") return "float";
+  if (s === "float8" || s === "double precision") return "double";
+  if (s === "bool" || s === "boolean") return "boolean";
+  if (s === "character varying") return "varchar";
+  if (s === "character") return "char";
+  return typeName;
+}