diff --git a/src/App.vue b/src/App.vue
index 0f869a181..67998e89a 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -29,6 +29,7 @@ import { useDataGridActions } from "@/composables/useDataGridActions";
 import { useTauriEvents } from "@/composables/useTauriEvents";
 import { setLocale, currentLocale } from "@/i18n";
 import * as api from "@/lib/api";
+import { resolveDefaultDatabase } from "@/lib/defaultDatabase";
 import { resolveExecutableSql } from "@/lib/sqlExecutionTarget";
 import { isTauriRuntime } from "@/lib/tauriRuntime";
 import { isCloseTabShortcut, isExecuteSqlShortcut } from "@/lib/keyboardShortcuts";
@@ -204,24 +205,31 @@ async function openSqlFile() {
   }
 }
 
-function newQuery() {
+async function newQuery() {
   const connId = connectionStore.activeConnectionId || connectionStore.connections[0]?.id;
   if (!connId) return;
   const conn = connectionStore.getConfig(connId);
   if (!conn) return;
   connectionStore.activeConnectionId = connId;
-  queryStore.createTab(conn.id, conn.database || "");
+  const tabId = queryStore.createTab(conn.id, resolveDefaultDatabase(conn, []));
+  try {
+    await connectionStore.ensureConnected(connId);
+    const options = await getDatabaseOptions(connId);
+    queryStore.updateDatabase(tabId, resolveDefaultDatabase(conn, options));
+  } catch (e: any) {
+    toast(t("connection.connectFailed", { message: e?.message || String(e) }), 5000);
+  }
 }
 
 async function openConnectionQuery(connectionId: string) {
   const connection = connectionStore.getConfig(connectionId);
   if (!connection) return;
   connectionStore.activeConnectionId = connectionId;
-  const tabId = queryStore.createTab(connectionId, connection.database || "");
+  const tabId = queryStore.createTab(connectionId, resolveDefaultDatabase(connection, []));
   try {
     await connectionStore.ensureConnected(connectionId);
     const options = await getDatabaseOptions(connectionId);
-    if (!connection.database && options[0]) queryStore.updateDatabase(tabId, options[0]);
+    queryStore.updateDatabase(tabId, resolveDefaultDatabase(connection, options));
   } catch (e: any) {
     toast(t("connection.connectFailed", { message: e?.message || String(e) }), 5000);
   }
@@ -253,12 +261,12 @@ async function changeActiveConnection(connectionId: string) {
   if (!tab) return;
   const connection = connectionStore.getConfig(connectionId);
   if (!connection) return;
-  queryStore.updateConnection(tab.id, connectionId, connection.database || "");
+  queryStore.updateConnection(tab.id, connectionId, resolveDefaultDatabase(connection, []));
   connectionStore.activeConnectionId = connectionId;
   try {
     await connectionStore.ensureConnected(connectionId);
     const options = await getDatabaseOptions(connectionId);
-    if (!connection.database && options[0]) queryStore.updateDatabase(tab.id, options[0]);
+    queryStore.updateDatabase(tab.id, resolveDefaultDatabase(connection, options));
   } catch (e: any) {
     toast(t("connection.connectFailed", { message: e?.message || String(e) }), 5000);
   }
@@ -269,6 +277,18 @@ function changeActiveDatabase(database: string) {
   if (tab) queryStore.updateDatabase(tab.id, database);
 }
 
+async function setActiveDatabaseAsDefault() {
+  const tab = activeTab.value;
+  if (!tab || !tab.connectionId || !tab.database) return;
+  await connectionStore.setDefaultDatabase(tab.connectionId, tab.database);
+}
+
+async function clearActiveDefaultDatabase() {
+  const tab = activeTab.value;
+  if (!tab || !tab.connectionId) return;
+  await connectionStore.clearDefaultDatabase(tab.connectionId);
+}
+
 function changeActiveSchema(schema: string | undefined) {
   const tab = activeTab.value;
   if (tab) queryStore.updateSchema(tab.id, schema);
@@ -453,6 +473,8 @@ onUnmounted(() => {
                   @change-connection="changeActiveConnection"
                   @change-database="changeActiveDatabase"
                   @change-schema="changeActiveSchema"
+                  @set-default-database="setActiveDatabaseAsDefault"
+                  @clear-default-database="clearActiveDefaultDatabase"
                 />
                 <ContentArea
                   :active-tab="activeTab"
diff --git a/src/components/editor/AiAssistant.vue b/src/components/editor/AiAssistant.vue
index b3555ce5b..8ed7a9b91 100644
--- a/src/components/editor/AiAssistant.vue
+++ b/src/components/editor/AiAssistant.vue
@@ -57,6 +57,7 @@ import {
 import type { AiMessage } from "@/lib/api";
 import type { ConnectionConfig, QueryTab } from "@/types/database";
 import { useDatabaseOptions } from "@/composables/useDatabaseOptions";
+import { resolveDefaultDatabase } from "@/lib/defaultDatabase";
 
 const { t } = useI18n();
 const settings = useSettingsStore();
@@ -143,12 +144,16 @@ async function changeConnection(connectionId: string) {
   connectionStore.activeConnectionId = connectionId;
   const tab = props.tab;
   if (tab) {
-    queryStore.updateConnection(tab.id, connectionId, conn.database || "");
+    queryStore.updateConnection(tab.id, connectionId, resolveDefaultDatabase(conn, []));
   } else {
-    queryStore.createTab(connectionId, conn.database || "");
+    queryStore.createTab(connectionId, resolveDefaultDatabase(conn, []));
   }
   try {
     await loadDatabaseOptions(connectionId);
+    const database = resolveDefaultDatabase(conn, allDbOptions.value[connectionId] || []);
+    if (tab) {
+      queryStore.updateDatabase(tab.id, database);
+    }
   } catch (e: any) {
     toast(t("connection.connectFailed", { message: e?.message || String(e) }), 5000);
   }
diff --git a/src/components/layout/EditorToolbar.vue b/src/components/layout/EditorToolbar.vue
index 3df791393..24711e863 100644
--- a/src/components/layout/EditorToolbar.vue
+++ b/src/components/layout/EditorToolbar.vue
@@ -6,6 +6,7 @@ import {
   Loader2,
   Square,
   Database,
+  Check,
   Table2,
   AlignLeft,
   GitBranch,
@@ -21,6 +22,7 @@ import { useConnectionStore } from "@/stores/connectionStore";
 import { useDatabaseOptions } from "@/composables/useDatabaseOptions";
 import { useSchemaOptions } from "@/composables/useSchemaOptions";
 import { connectionIconType } from "@/lib/connectionPresentation";
+import { isDefaultDatabase } from "@/lib/defaultDatabase";
 import { connectionDisplayName } from "@/lib/tabPresentation";
 import type { QueryTab, ConnectionConfig } from "@/types/database";
 
@@ -40,6 +42,8 @@ const emit = defineEmits<{
   changeConnection: [connectionId: string];
   changeDatabase: [database: string];
   changeSchema: [schema: string | undefined];
+  setDefaultDatabase: [];
+  clearDefaultDatabase: [];
 }>();
 
 const { t } = useI18n();
@@ -67,6 +71,8 @@ const activeSchemaOptions = computed(() => {
   return getSchemaOptionsForDb(connection.id, props.activeTab.database);
 });
 
+const isActiveDatabaseDefault = computed(() => isDefaultDatabase(props.activeConnection, activeDatabaseValue.value));
+
 function databaseDisplayName(database: string): string {
   const connection = props.activeConnection;
   if (connection?.db_type === "redis" && database !== "") return `db${database}`;
@@ -210,6 +216,16 @@ function databaseDisplayName(database: string): string {
             </SelectItem>
           </SelectContent>
         </Select>
+        <Button
+          v-if="activeDatabaseValue"
+          variant="ghost"
+          size="sm"
+          class="h-6 px-2 text-[11px]"
+          @click="isActiveDatabaseDefault ? emit('clearDefaultDatabase') : emit('setDefaultDatabase')"
+        >
+          <Check v-if="isActiveDatabaseDefault" class="h-3 w-3" />
+          {{ isActiveDatabaseDefault ? t("editor.defaultDatabase") : t("editor.setDefaultDatabase") }}
+        </Button>
       </div>
       <div v-if="showSchemaSelector" class="flex items-center gap-1">
         <Layers class="h-3.5 w-3.5 shrink-0" />
diff --git a/src/components/sidebar/TreeItem.vue b/src/components/sidebar/TreeItem.vue
index 850d1b029..b092b8d04 100644
--- a/src/components/sidebar/TreeItem.vue
+++ b/src/components/sidebar/TreeItem.vue
@@ -51,8 +51,10 @@ import {
 import { useConnectionStore } from "@/stores/connectionStore";
 import { useQueryStore } from "@/stores/queryStore";
 import { useToast } from "@/composables/useToast";
+import { useDatabaseOptions } from "@/composables/useDatabaseOptions";
 import type { DatabaseType, QueryResult, TreeNode, TreeNodeType } from "@/types/database";
 import * as api from "@/lib/api";
+import { resolveDefaultDatabase } from "@/lib/defaultDatabase";
 import {
   DATABASE_EXPORT_PAGE_SIZE,
   DATABASE_EXPORT_ROW_LIMIT,
@@ -80,12 +82,14 @@ import DatabaseIcon from "@/components/icons/DatabaseIcon.vue";
 import ConnectionErrorIndicator from "@/components/connection/ConnectionErrorIndicator.vue";
 import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter } from "@/components/ui/dialog";
 import { Button } from "@/components/ui/button";
+import { Badge } from "@/components/ui/badge";
 import { Input } from "@/components/ui/input";
 
 const { t } = useI18n();
 const connectionStore = useConnectionStore();
 const queryStore = useQueryStore();
 const { toast } = useToast();
+const { getDatabaseOptions } = useDatabaseOptions();
 
 const props = defineProps<{
   node: TreeNode;
@@ -295,12 +299,39 @@ async function newQuery() {
   try {
     await connectionStore.ensureConnected(node.connectionId);
     connectionStore.activeConnectionId = node.connectionId;
-    queryStore.createTab(node.connectionId, node.database || "", undefined, "query");
+    if (node.database) {
+      queryStore.createTab(node.connectionId, node.database, undefined, "query");
+      return;
+    }
+    const connection = connectionStore.getConfig(node.connectionId);
+    if (!connection) return;
+    const options = await getDatabaseOptions(node.connectionId);
+    queryStore.createTab(node.connectionId, resolveDefaultDatabase(connection, options), undefined, "query");
   } catch (e: any) {
     toast(t("connection.connectFailed", { message: e?.message || String(e) }), 5000);
   }
 }
 
+async function setNodeAsDefaultDatabase() {
+  const node = props.node;
+  if (!node.connectionId || !node.database) return;
+  try {
+    await connectionStore.setDefaultDatabase(node.connectionId, node.database);
+  } catch (e: any) {
+    toast(t("connection.saveFailed", { message: e?.message || String(e) }), 5000);
+  }
+}
+
+async function clearNodeDefaultDatabase() {
+  const node = props.node;
+  if (!node.connectionId) return;
+  try {
+    await connectionStore.clearDefaultDatabase(node.connectionId);
+  } catch (e: any) {
+    toast(t("connection.saveFailed", { message: e?.message || String(e) }), 5000);
+  }
+}
+
 async function refresh() {
   const node = props.node;
   node.isExpanded = false;
@@ -818,6 +849,13 @@ const canOpenFieldLineage = computed(() => {
   );
 });
 const isPinned = computed(() => props.node.pinned || connectionStore.isTreeNodePinned(props.node.id));
+const isNodeDefaultDatabase = computed(
+  () =>
+    (props.node.type === "database" || props.node.type === "redis-db" || props.node.type === "mongo-db") &&
+    !!props.node.connectionId &&
+    !!props.node.database &&
+    connectionStore.isDefaultDatabase(props.node.connectionId, props.node.database),
+);
 const hasTypeMenu = computed(() => {
   const t = props.node.type;
   return (
@@ -1047,6 +1085,9 @@ const isDragging = computed(() => dragState.active && dragState.draggedId === pr
             @vue:mounted="($event: any) => $event.el.focus()"
           />
           <span v-else class="min-w-0 flex-1 truncate">{{ isGroupLabel(node) ? t(node.label) : node.label }}</span>
+          <Badge v-if="isNodeDefaultDatabase" variant="secondary" class="h-4 px-1.5 text-[10px]">
+            {{ t("editor.defaultDatabase") }}
+          </Badge>
           <span v-if="columnComment" class="truncate text-muted-foreground/60 text-[10px] max-w-[40%]">{{
             columnComment
           }}</span>
@@ -1165,6 +1206,12 @@ const isDragging = computed(() => dragState.active && dragState.draggedId === pr
         <ContextMenuItem @click="newQuery">
           <TerminalSquare class="w-4 h-4" /> {{ t("contextMenu.newQuery") }}
         </ContextMenuItem>
+        <ContextMenuItem v-if="node.type === 'database' && !isNodeDefaultDatabase" @click="setNodeAsDefaultDatabase">
+          <Database class="w-4 h-4" /> {{ t("contextMenu.setDefaultDatabase") }}
+        </ContextMenuItem>
+        <ContextMenuItem v-if="node.type === 'database' && isNodeDefaultDatabase" @click="clearNodeDefaultDatabase">
+          <Database class="w-4 h-4" /> {{ t("contextMenu.clearDefaultDatabase") }}
+        </ContextMenuItem>
         <ContextMenuItem v-if="canCreateTable" @click="createTable">
           <Plus class="w-4 h-4" /> {{ t("contextMenu.createTable") }}
         </ContextMenuItem>
@@ -1194,6 +1241,18 @@ const isDragging = computed(() => dragState.active && dragState.draggedId === pr
         </ContextMenuItem>
       </template>
 
+      <template v-if="node.type === 'redis-db' || node.type === 'mongo-db'">
+        <ContextMenuItem @click="newQuery">
+          <TerminalSquare class="w-4 h-4" /> {{ t("contextMenu.newQuery") }}
+        </ContextMenuItem>
+        <ContextMenuItem v-if="!isNodeDefaultDatabase" @click="setNodeAsDefaultDatabase">
+          <Database class="w-4 h-4" /> {{ t("contextMenu.setDefaultDatabase") }}
+        </ContextMenuItem>
+        <ContextMenuItem v-if="isNodeDefaultDatabase" @click="clearNodeDefaultDatabase">
+          <Database class="w-4 h-4" /> {{ t("contextMenu.clearDefaultDatabase") }}
+        </ContextMenuItem>
+      </template>
+
       <template v-if="node.type === 'table' || node.type === 'view'">
         <ContextMenuItem @click="openData">
           <TableProperties class="w-4 h-4" /> {{ t("contextMenu.viewData") }}
diff --git a/src/i18n/locales/en.ts b/src/i18n/locales/en.ts
index 381ac9a59..8533375b2 100644
--- a/src/i18n/locales/en.ts
+++ b/src/i18n/locales/en.ts
@@ -134,6 +134,8 @@ export default {
     selectConnection: "Select connection",
     selectDatabase: "Select database",
     selectSchema: "Select schema",
+    setDefaultDatabase: "Set Default",
+    defaultDatabase: "Default",
   },
   tabs: {
     sql: "SQL",
@@ -415,6 +417,8 @@ export default {
     closeOtherTabs: "Close Other Tabs",
     closeAllTabs: "Close All Tabs",
     copyName: "Copy Name",
+    setDefaultDatabase: "Set as Default Database",
+    clearDefaultDatabase: "Clear Default Database",
     exportDatabase: "Export Database",
     exportDatabaseSuccess: "Exported {count} tables, up to {limit} rows each",
     exportDatabaseFailed: "Failed to export database: {message}",
diff --git a/src/i18n/locales/zh-CN.ts b/src/i18n/locales/zh-CN.ts
index 6c13b92b5..40cc9ac81 100644
--- a/src/i18n/locales/zh-CN.ts
+++ b/src/i18n/locales/zh-CN.ts
@@ -133,6 +133,8 @@ export default {
     selectConnection: "选择连接",
     selectDatabase: "选择数据库",
     selectSchema: "选择模式",
+    setDefaultDatabase: "设为默认",
+    defaultDatabase: "默认库",
   },
   tabs: {
     sql: "SQL",
@@ -407,6 +409,8 @@ export default {
     closeOtherTabs: "关闭其他标签页",
     closeAllTabs: "关闭全部标签页",
     copyName: "复制名称",
+    setDefaultDatabase: "设为默认数据库",
+    clearDefaultDatabase: "取消默认数据库",
     exportDatabase: "导出数据库",
     exportDatabaseSuccess: "已导出 {count} 张表，每表最多 {limit} 行",
     exportDatabaseFailed: "导出数据库失败：{message}",
diff --git a/src/lib/defaultDatabase.ts b/src/lib/defaultDatabase.ts
new file mode 100644
index 000000000..c0c6cccb7
--- /dev/null
+++ b/src/lib/defaultDatabase.ts
@@ -0,0 +1,12 @@
+import type { ConnectionConfig } from "@/types/database";
+
+export function resolveDefaultDatabase(connection: Pick<ConnectionConfig, "database">, options: string[]): string {
+  return connection.database || options[0] || "";
+}
+
+export function isDefaultDatabase(
+  connection: Pick<ConnectionConfig, "database"> | undefined,
+  database: string,
+): boolean {
+  return !!connection?.database && !!database && connection.database === database;
+}
diff --git a/src/stores/connectionStore.ts b/src/stores/connectionStore.ts
index 08812086e..25bc2d028 100644
--- a/src/stores/connectionStore.ts
+++ b/src/stores/connectionStore.ts
@@ -264,6 +264,28 @@ export const useConnectionStore = defineStore("connection", () => {
     invalidateCompletionCache(config.id);
   }
 
+  async function setDefaultDatabase(connectionId: string, database: string) {
+    const config = getConfig(connectionId);
+    if (!config || config.database === database) return;
+    await updateConnection({
+      ...config,
+      database,
+    });
+  }
+
+  async function clearDefaultDatabase(connectionId: string) {
+    const config = getConfig(connectionId);
+    if (!config || !config.database) return;
+    await updateConnection({
+      ...config,
+      database: undefined,
+    });
+  }
+
+  function isDefaultDatabase(connectionId: string, database: string): boolean {
+    return getConfig(connectionId)?.database === database && database !== "";
+  }
+
   async function connect(config: ConnectionConfig) {
     config = normalizeConnection(config);
     const pendingNode = findNode(treeNodes.value, config.id);
@@ -934,6 +956,9 @@ export const useConnectionStore = defineStore("connection", () => {
     addConnection,
     addEphemeralConnection,
     updateConnection,
+    setDefaultDatabase,
+    clearDefaultDatabase,
+    isDefaultDatabase,
     removeConnection,
     editingConnectionId,
     startEditing,
diff --git a/tests/defaultDatabase.test.ts b/tests/defaultDatabase.test.ts
new file mode 100644
index 000000000..02e6115c3
--- /dev/null
+++ b/tests/defaultDatabase.test.ts
@@ -0,0 +1,22 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import { isDefaultDatabase, resolveDefaultDatabase } from "../src/lib/defaultDatabase.ts";
+
+test("优先使用连接上已保存的默认数据库", () => {
+  assert.equal(resolveDefaultDatabase({ database: "analytics" }, ["app", "analytics"]), "analytics");
+});
+
+test("默认数据库为空时回退到首个可选数据库", () => {
+  assert.equal(resolveDefaultDatabase({ database: undefined }, ["app", "analytics"]), "app");
+});
+
+test("没有默认数据库且无候选项时返回空字符串", () => {
+  assert.equal(resolveDefaultDatabase({ database: undefined }, []), "");
+});
+
+test("判断当前数据库是否为默认数据库", () => {
+  assert.equal(isDefaultDatabase({ database: "analytics" }, "analytics"), true);
+  assert.equal(isDefaultDatabase({ database: "analytics" }, "app"), false);
+  assert.equal(isDefaultDatabase(undefined, "analytics"), false);
+  assert.equal(isDefaultDatabase({ database: "analytics" }, ""), false);
+});