fix(dameng): preserve cloned column comments

apps/desktop/src/components/objects/ObjectBrowser.vue

@@ -60,7 +60,18 @@ import { supportsSchemaDiagram, supportsTableImport, supportsTableStructureEditi
 import { codeMirrorSqlDialect, connectionObjectTreeNodeSchema, connectionUsesDatabaseObjectTreeMode, effectiveDatabaseTypeForConnection, tableStructureDatabaseTypeForConnection } from "@/lib/database/jdbcDialect";
 import { getTableMetadataCapabilities, type TableMetadataCapabilities } from "@/lib/table/tableMetadataCapabilities";
 import { buildTableSelectSql } from "@/lib/table/tableSelectSql";
-import { buildDropObjectSql, buildDropTableSql, buildDuplicateTableStructureSql, buildCopyTableDataSql, buildEmptyTableSql, buildTruncateTableSql, supportsDropTableCascade, supportsTruncateTableCascade, type TableAdminSqlOptions } from "@/lib/database/dbAdminSql";
+import {
+  buildDropObjectSql,
+  buildDropTableSql,
+  buildDuplicateTableStructureSql,
+  buildCopyTableDataSql,
+  buildEmptyTableSql,
+  buildTruncateTableSql,
+  collectDuplicateTableColumnComments,
+  supportsDropTableCascade,
+  supportsTruncateTableCascade,
+  type TableAdminSqlOptions,
+} from "@/lib/database/dbAdminSql";
 import { useToast } from "@/composables/useToast";
 import { buildExecutableObjectSourceStatements, buildRoutineRenameObjectSourceStatements, executeObjectSourceSave, formatObjectSourceSaveError, supportsSourceBackedRoutineRename } from "@/lib/table/objectSourceEditor";
 import { buildRenameObjectSql, supportsObjectRename } from "@/lib/table/objectRenameSql";
@@ -1809,6 +1820,30 @@ function requestDuplicateStructure(row: ObjectBrowserRow) {
   showDuplicateDialog.value = true;
 }
 
+async function buildDuplicateStructurePlan(sourceName: string, targetName: string, schema: string | undefined, sourceColumns?: ColumnInfo[]) {
+  let columns = sourceColumns;
+  if (effectiveDatabaseType.value === "dameng" && !columns) {
+    try {
+      columns = await api.getColumns(props.connection.id, props.database, schema || "", sourceName, props.catalog);
+    } catch (error) {
+      console.warn(`Failed to load Dameng column comments for table clone: ${sourceName}`, error);
+    }
+  }
+  const columnComments = effectiveDatabaseType.value === "dameng" ? collectDuplicateTableColumnComments(columns ?? []) : [];
+  const sql = await buildDuplicateTableStructureSql({
+    databaseType: effectiveDatabaseType.value,
+    schema,
+    sourceName,
+    targetName,
+    columnComments,
+  });
+  return { sql, sourceColumns: columns, executeAsScript: columnComments.length > 0 };
+}
+
+function executeDuplicateStructurePlan(plan: { sql: string; executeAsScript: boolean }, schema: string | undefined) {
+  return plan.executeAsScript ? api.executeScript(props.connection.id, props.database, plan.sql, schema) : api.executeQuery(props.connection.id, props.database, plan.sql, schema);
+}
+
 async function confirmDuplicateStructure() {
   const row = duplicateTarget.value;
   const newName = duplicateTableName.value.trim();
@@ -1816,13 +1851,8 @@ async function confirmDuplicateStructure() {
   showDuplicateDialog.value = false;
   try {
     const schema = row.schema || selectedSchema.value;
-    const sql = await buildDuplicateTableStructureSql({
-      databaseType: effectiveDatabaseType.value,
-      schema,
-      sourceName: row.name,
-      targetName: newName,
-    });
-    const executed = await executeObjectBrowserSqlWithProductionGuard(sql, () => api.executeQuery(props.connection.id, props.database, sql, schema));
+    const plan = await buildDuplicateStructurePlan(row.name, newName, schema);
+    const executed = await executeObjectBrowserSqlWithProductionGuard(plan.sql, () => executeDuplicateStructurePlan(plan, schema));
     if (!executed) return;
     toast(t("contextMenu.duplicateStructureSuccess", { name: newName }));
     await reload();
@@ -1919,18 +1949,15 @@ async function confirmPasteTable() {
     const targetName = entry.targetName.trim();
     const schema = entry.schema || selectedSchema.value;
     try {
+      let sourceColumns: ColumnInfo[] | undefined;
       if (mode === "structure-and-data" || mode === "structure-only") {
-        const structureSql = await buildDuplicateTableStructureSql({
-          databaseType: effectiveDatabaseType.value,
-          schema,
-          sourceName: entry.sourceName,
-          targetName,
-        });
-        const executed = await executeObjectBrowserSqlWithProductionGuard(structureSql, () => api.executeQuery(props.connection.id, props.database, structureSql, schema));
+        const plan = await buildDuplicateStructurePlan(entry.sourceName, targetName, schema, sourceColumns);
+        sourceColumns = plan.sourceColumns;
+        const executed = await executeObjectBrowserSqlWithProductionGuard(plan.sql, () => executeDuplicateStructurePlan(plan, schema));
         if (!executed) return;
       }
       if (copyData) {
-        const sourceColumns = await api.getColumns(props.connection.id, props.database, schema || "", entry.sourceName, props.catalog);
+        sourceColumns ??= await api.getColumns(props.connection.id, props.database, schema || "", entry.sourceName, props.catalog);
         const dataCopyColumnOptions = tableDataCopyColumnOptions(effectiveDatabaseType.value, sourceColumns);
         if (dataCopyColumnOptions.columns.length === 0) {
           throw new Error("No writable columns available for table data copy.");

apps/desktop/src/lib/__tests__/database/dbAdminSql.spec.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it } from "vitest";
+import { collectDuplicateTableColumnComments } from "@/lib/database/dbAdminSql";
+
+describe("collectDuplicateTableColumnComments", () => {
+  it("preserves meaningful whitespace and excludes whitespace-only comments", () => {
+    expect(
+      collectDuplicateTableColumnComments([
+        { name: "LEADING", comment: "  leading" },
+        { name: "TRAILING", comment: "trailing  " },
+        { name: "BOTH", comment: "  Owner's; display name  " },
+        { name: "WHITESPACE_ONLY", comment: " \t\n" },
+        { name: "EMPTY", comment: "" },
+        { name: "NULL", comment: null },
+      ]),
+    ).toEqual([
+      { name: "LEADING", comment: "  leading" },
+      { name: "TRAILING", comment: "trailing  " },
+      { name: "BOTH", comment: "  Owner's; display name  " },
+    ]);
+  });
+});

apps/desktop/src/lib/database/dbAdminSql.ts

@@ -1,4 +1,4 @@
-import type { DatabaseObjectType, DatabaseType } from "@/types/database";
+import type { ColumnInfo, DatabaseObjectType, DatabaseType } from "@/types/database";
 import * as api from "@/lib/backend/api";
 
 export interface DropObjectSqlOptions {
@@ -55,6 +55,14 @@ export interface DuplicateTableStructureSqlOptions {
   schema?: string | null;
   sourceName: string;
   targetName: string;
+  columnComments?: Array<{ name: string; comment: string }>;
+}
+
+export function collectDuplicateTableColumnComments(columns: readonly Pick<ColumnInfo, "name" | "comment">[]): Array<{ name: string; comment: string }> {
+  return columns.flatMap((column) => {
+    const comment = column.comment;
+    return comment?.trim() ? [{ name: column.name, comment }] : [];
+  });
 }
 
 export interface CopyTableDataSqlOptions {