diff --git a/src/App.vue b/src/App.vue
index 897f872bd8..b591546072 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -34,6 +34,7 @@ import DatabaseIcon from "@/components/icons/DatabaseIcon.vue";
 import QueryHistory from "@/components/editor/QueryHistory.vue";
 import DangerConfirmDialog from "@/components/editor/DangerConfirmDialog.vue";
 import DataTransferDialog from "@/components/transfer/DataTransferDialog.vue";
+import SchemaDiffDialog from "@/components/diff/SchemaDiffDialog.vue";
 import type { ConnectionConfig } from "@/types/database";
 import { useConnectionStore } from "@/stores/connectionStore";
 import { useQueryStore } from "@/stores/queryStore";
@@ -102,8 +103,11 @@ const selectedSql = ref("");
 const formatSqlRequestId = ref(0);
 const showDangerDialog = ref(false);
 const showTransferDialog = ref(false);
+const showSchemaDiffDialog = ref(false);
 const transferPrefillConnectionId = ref("");
 const transferPrefillDatabase = ref("");
+const schemaDiffPrefillConnectionId = ref("");
+const schemaDiffPrefillDatabase = ref("");
 const databaseOptions = ref<Record<string, string[]>>({});
 const loadingDatabaseOptions = ref<Record<string, boolean>>({});
 const checkingUpdates = ref(false);
@@ -135,6 +139,15 @@ watch(() => connectionStore.transferSource, (v) => {
   }
 });
 
+watch(() => connectionStore.schemaDiffSource, (v) => {
+  if (v) {
+    schemaDiffPrefillConnectionId.value = v.connectionId;
+    schemaDiffPrefillDatabase.value = v.database;
+    showSchemaDiffDialog.value = true;
+    connectionStore.schemaDiffSource = null;
+  }
+});
+
 function onConnectionConnectStarted(name: string) {
   toast(t("connection.connecting", { name }), 30000);
 }
@@ -1140,6 +1153,11 @@ async function setupFileDrop() {
         :prefill-connection-id="transferPrefillConnectionId"
         :prefill-database="transferPrefillDatabase"
       />
+      <SchemaDiffDialog
+        v-model:open="showSchemaDiffDialog"
+        :prefill-connection-id="schemaDiffPrefillConnectionId"
+        :prefill-database="schemaDiffPrefillDatabase"
+      />
       <Dialog v-model:open="showUpdateDialog">
         <DialogContent class="sm:max-w-[520px]">
           <DialogHeader>
diff --git a/src/components/diff/SchemaDiffDialog.vue b/src/components/diff/SchemaDiffDialog.vue
new file mode 100644
index 0000000000..1754cd7a12
--- /dev/null
+++ b/src/components/diff/SchemaDiffDialog.vue
@@ -0,0 +1,386 @@
+<script setup lang="ts">
+import { computed, ref, watch } from "vue";
+import { useI18n } from "vue-i18n";
+import {
+  Dialog, DialogHeader, DialogTitle,
+  DialogFooter, DialogContent,
+} from "@/components/ui/dialog";
+import { Button } from "@/components/ui/button";
+import { Badge } from "@/components/ui/badge";
+import {
+  Select, SelectContent, SelectItem, SelectTrigger, SelectValue,
+} from "@/components/ui/select";
+import { useConnectionStore } from "@/stores/connectionStore";
+import DatabaseIcon from "@/components/icons/DatabaseIcon.vue";
+import * as api from "@/lib/tauri";
+import {
+  diffColumns, diffIndexes, diffTables, generateSyncSql,
+  type TableDiff,
+} from "@/lib/schemaDiff";
+import { useToast } from "@/composables/useToast";
+import { Loader2, Copy, Play, GitCompareArrows } from "lucide-vue-next";
+
+const { t } = useI18n();
+const { toast } = useToast();
+const open = defineModel<boolean>("open", { default: false });
+const store = useConnectionStore();
+
+const props = defineProps<{
+  prefillConnectionId?: string;
+  prefillDatabase?: string;
+}>();
+
+const sourceConnectionId = ref("");
+const sourceDatabase = ref("");
+const sourceDatabases = ref<string[]>([]);
+const sourceSchema = ref("");
+
+const targetConnectionId = ref("");
+const targetDatabase = ref("");
+const targetDatabases = ref<string[]>([]);
+const targetSchema = ref("");
+
+const step = ref<"select" | "comparing" | "result">("select");
+const diffs = ref<TableDiff[]>([]);
+const syncSql = ref("");
+const executing = ref(false);
+
+const sqlConnections = computed(() =>
+  store.connections.filter((c) =>
+    !["redis", "mongodb", "elasticsearch"].includes(c.db_type),
+  ),
+);
+
+const canCompare = computed(() =>
+  sourceConnectionId.value && sourceDatabase.value &&
+  targetConnectionId.value && targetDatabase.value,
+);
+
+function connectionIconType(connectionId: string) {
+  const config = store.getConfig(connectionId);
+  return config?.driver_profile || config?.db_type || "mysql";
+}
+
+async function loadDatabases(connectionId: string, side: "source" | "target") {
+  if (!connectionId) return;
+  try {
+    await store.ensureConnected(connectionId);
+    const dbs = await api.listDatabases(connectionId);
+    const names = dbs.map((d) => d.name);
+    if (side === "source") {
+      sourceDatabases.value = names;
+      sourceDatabase.value = names.length === 1 ? names[0] : "";
+    } else {
+      targetDatabases.value = names;
+      targetDatabase.value = names.length === 1 ? names[0] : "";
+    }
+  } catch {
+    if (side === "source") sourceDatabases.value = [];
+    else targetDatabases.value = [];
+  }
+}
+
+async function resolveSchema(connectionId: string, database: string): Promise<string> {
+  const config = store.getConfig(connectionId);
+  const needsSchema = config?.db_type === "postgres" || config?.db_type === "sqlserver" || config?.db_type === "oracle" || config?.db_type === "redshift";
+  if (needsSchema) {
+    const schemas = await api.listSchemas(connectionId, database);
+    return schemas.includes("public") ? "public" : (schemas[0] ?? "");
+  }
+  return database;
+}
+
+async function startCompare() {
+  if (!canCompare.value) return;
+  step.value = "comparing";
+  diffs.value = [];
+  syncSql.value = "";
+
+  try {
+    await store.ensureConnected(sourceConnectionId.value);
+    await store.ensureConnected(targetConnectionId.value);
+
+    const srcSchema = await resolveSchema(sourceConnectionId.value, sourceDatabase.value);
+    const tgtSchema = await resolveSchema(targetConnectionId.value, targetDatabase.value);
+    sourceSchema.value = srcSchema;
+    targetSchema.value = tgtSchema;
+
+    const [srcTables, tgtTables] = await Promise.all([
+      api.listTables(sourceConnectionId.value, sourceDatabase.value, srcSchema),
+      api.listTables(targetConnectionId.value, targetDatabase.value, tgtSchema),
+    ]);
+
+    const srcNames = srcTables.filter((t) => t.table_type !== "VIEW").map((t) => t.name);
+    const tgtNames = tgtTables.filter((t) => t.table_type !== "VIEW").map((t) => t.name);
+    const { added, removed, common } = diffTables(srcNames, tgtNames);
+
+    const result: TableDiff[] = [];
+
+    for (const name of added) {
+      const ddl = await api.getTableDdl(sourceConnectionId.value, sourceDatabase.value, srcSchema, name);
+      result.push({ type: "added", name, ddl });
+    }
+
+    for (const name of removed) {
+      result.push({ type: "removed", name });
+    }
+
+    for (const name of common) {
+      const [srcCols, tgtCols, srcIdx, tgtIdx] = await Promise.all([
+        api.getColumns(sourceConnectionId.value, sourceDatabase.value, srcSchema, name),
+        api.getColumns(targetConnectionId.value, targetDatabase.value, tgtSchema, name),
+        api.listIndexes(sourceConnectionId.value, sourceDatabase.value, srcSchema, name),
+        api.listIndexes(targetConnectionId.value, targetDatabase.value, tgtSchema, name),
+      ]);
+
+      const colDiffs = diffColumns(srcCols, tgtCols);
+      const idxDiffs = diffIndexes(srcIdx, tgtIdx);
+
+      if (colDiffs.length > 0 || idxDiffs.length > 0) {
+        result.push({
+          type: "modified",
+          name,
+          columns: colDiffs.length > 0 ? colDiffs : undefined,
+          indexes: idxDiffs.length > 0 ? idxDiffs : undefined,
+        });
+      }
+    }
+
+    diffs.value = result;
+    const srcConfig = store.getConfig(targetConnectionId.value);
+    syncSql.value = generateSyncSql(result, srcConfig?.db_type || "mysql");
+    step.value = "result";
+  } catch (e: any) {
+    toast(e?.message || String(e), 5000);
+    step.value = "select";
+  }
+}
+
+async function executeSql() {
+  if (!syncSql.value.trim() || executing.value) return;
+  executing.value = true;
+  try {
+    await store.ensureConnected(targetConnectionId.value);
+    const statements = syncSql.value
+      .split(";")
+      .map((s) => s.trim())
+      .filter((s) => s && !s.startsWith("--"));
+
+    for (const sql of statements) {
+      await api.executeQuery(targetConnectionId.value, targetDatabase.value, sql);
+    }
+    toast(t("diff.syncSuccess"), 2000);
+    open.value = false;
+  } catch (e: any) {
+    toast(e?.message || String(e), 5000);
+  } finally {
+    executing.value = false;
+  }
+}
+
+function copySql() {
+  navigator.clipboard.writeText(syncSql.value);
+  toast(t("grid.copied"));
+}
+
+function diffBadgeVariant(type: string) {
+  if (type === "added") return "default";
+  if (type === "removed") return "destructive";
+  return "secondary";
+}
+
+function diffLabel(type: string) {
+  if (type === "added") return t("diff.added");
+  if (type === "removed") return t("diff.removed");
+  return t("diff.modified");
+}
+
+function resetResult() {
+  step.value = "select";
+  diffs.value = [];
+  syncSql.value = "";
+}
+
+watch(sourceConnectionId, (id) => {
+  sourceDatabase.value = "";
+  loadDatabases(id, "source");
+  resetResult();
+});
+
+watch(targetConnectionId, (id) => {
+  targetDatabase.value = "";
+  loadDatabases(id, "target");
+  resetResult();
+});
+
+watch(sourceDatabase, () => resetResult());
+watch(targetDatabase, () => resetResult());
+
+watch(open, async (val) => {
+  if (val) {
+    step.value = "select";
+    diffs.value = [];
+    syncSql.value = "";
+    if (props.prefillConnectionId) {
+      sourceConnectionId.value = props.prefillConnectionId;
+      await loadDatabases(props.prefillConnectionId, "source");
+      if (props.prefillDatabase) {
+        sourceDatabase.value = props.prefillDatabase;
+      }
+    }
+  }
+});
+</script>
+
+<template>
+  <Dialog v-model:open="open">
+    <DialogContent class="sm:max-w-2xl max-h-[80vh] flex flex-col overflow-hidden">
+      <DialogHeader>
+        <DialogTitle class="flex items-center gap-2">
+          <GitCompareArrows class="w-4 h-4" />
+          {{ t('diff.title') }}
+        </DialogTitle>
+      </DialogHeader>
+
+      <div class="flex-1 min-h-0 overflow-auto space-y-4 py-2">
+        <!-- Source / Target Selection -->
+        <div class="grid grid-cols-2 gap-4">
+          <div class="space-y-2">
+            <Label class="text-xs font-medium">{{ t('diff.source') }}</Label>
+            <Select :model-value="sourceConnectionId" @update:model-value="(v: any) => sourceConnectionId = String(v)">
+              <SelectTrigger class="h-8 text-xs">
+                <div class="flex items-center gap-2">
+                  <DatabaseIcon v-if="sourceConnectionId" :db-type="connectionIconType(sourceConnectionId)" class="w-3.5 h-3.5" />
+                  <SelectValue :placeholder="t('diff.selectConnection')" />
+                </div>
+              </SelectTrigger>
+              <SelectContent>
+                <SelectItem v-for="c in sqlConnections" :key="c.id" :value="c.id">
+                  <div class="flex items-center gap-2">
+                    <DatabaseIcon :db-type="c.driver_profile || c.db_type" class="w-3.5 h-3.5" />
+                    {{ c.name }}
+                  </div>
+                </SelectItem>
+              </SelectContent>
+            </Select>
+            <Select v-if="sourceDatabases.length" :model-value="sourceDatabase" @update:model-value="(v: any) => sourceDatabase = String(v)">
+              <SelectTrigger class="h-8 text-xs">
+                <SelectValue :placeholder="t('diff.selectDatabase')" />
+              </SelectTrigger>
+              <SelectContent>
+                <SelectItem v-for="db in sourceDatabases" :key="db" :value="db">{{ db }}</SelectItem>
+              </SelectContent>
+            </Select>
+          </div>
+
+          <div class="space-y-2">
+            <Label class="text-xs font-medium">{{ t('diff.target') }}</Label>
+            <Select :model-value="targetConnectionId" @update:model-value="(v: any) => targetConnectionId = String(v)">
+              <SelectTrigger class="h-8 text-xs">
+                <div class="flex items-center gap-2">
+                  <DatabaseIcon v-if="targetConnectionId" :db-type="connectionIconType(targetConnectionId)" class="w-3.5 h-3.5" />
+                  <SelectValue :placeholder="t('diff.selectConnection')" />
+                </div>
+              </SelectTrigger>
+              <SelectContent>
+                <SelectItem v-for="c in sqlConnections" :key="c.id" :value="c.id">
+                  <div class="flex items-center gap-2">
+                    <DatabaseIcon :db-type="c.driver_profile || c.db_type" class="w-3.5 h-3.5" />
+                    {{ c.name }}
+                  </div>
+                </SelectItem>
+              </SelectContent>
+            </Select>
+            <Select v-if="targetDatabases.length" :model-value="targetDatabase" @update:model-value="(v: any) => targetDatabase = String(v)">
+              <SelectTrigger class="h-8 text-xs">
+                <SelectValue :placeholder="t('diff.selectDatabase')" />
+              </SelectTrigger>
+              <SelectContent>
+                <SelectItem v-for="db in targetDatabases" :key="db" :value="db">{{ db }}</SelectItem>
+              </SelectContent>
+            </Select>
+          </div>
+        </div>
+
+        <Button v-if="step === 'select'" size="sm" :disabled="!canCompare" @click="startCompare">
+          <GitCompareArrows class="w-3.5 h-3.5 mr-1" />
+          {{ t('diff.compare') }}
+        </Button>
+
+        <!-- Comparing -->
+        <div v-if="step === 'comparing'" class="flex items-center justify-center py-8 text-sm text-muted-foreground">
+          <Loader2 class="w-4 h-4 animate-spin mr-2" />
+          {{ t('diff.comparing') }}
+        </div>
+
+        <!-- Results -->
+        <template v-if="step === 'result'">
+          <div v-if="diffs.length === 0" class="py-6 text-center text-sm text-muted-foreground">
+            {{ t('diff.noDifferences') }}
+          </div>
+
+          <template v-else>
+            <!-- Diff Table -->
+            <div class="border rounded-lg overflow-hidden">
+              <div class="max-h-60 overflow-auto">
+                <table class="w-full text-xs table-fixed">
+                  <thead class="bg-muted sticky top-0 z-10">
+                    <tr>
+                      <th class="text-left px-3 py-2 font-medium w-1/4">{{ t('diff.table') }}</th>
+                      <th class="text-left px-3 py-2 font-medium w-16">{{ t('diff.status') }}</th>
+                      <th class="text-left px-3 py-2 font-medium">{{ t('diff.details') }}</th>
+                    </tr>
+                  </thead>
+                  <tbody>
+                    <tr v-for="d in diffs" :key="d.name" class="border-t border-border/50 hover:bg-accent/30">
+                      <td class="px-3 py-1.5 font-mono truncate">{{ d.name }}</td>
+                      <td class="px-3 py-1.5">
+                        <Badge :variant="diffBadgeVariant(d.type)" class="text-[10px] h-4 px-1.5">
+                          {{ diffLabel(d.type) }}
+                        </Badge>
+                      </td>
+                      <td class="px-3 py-1.5 text-muted-foreground">
+                        <template v-if="d.type === 'modified' && d.columns">
+                          <span v-for="(col, ci) in d.columns" :key="ci">
+                            <span :class="{
+                              'text-green-500': col.type === 'added',
+                              'text-red-500': col.type === 'removed',
+                              'text-yellow-500': col.type === 'modified',
+                            }">{{ col.type === 'added' ? '+' : col.type === 'removed' ? '-' : '~' }}{{ col.name }}</span>
+                            <span v-if="ci < d.columns!.length - 1">, </span>
+                          </span>
+                        </template>
+                        <span v-else-if="d.type === 'added'" class="text-green-500">{{ t('diff.newTable') }}</span>
+                        <span v-else-if="d.type === 'removed'" class="text-red-500">{{ t('diff.dropTable') }}</span>
+                      </td>
+                    </tr>
+                  </tbody>
+                </table>
+              </div>
+            </div>
+
+            <!-- SQL Preview -->
+            <div class="space-y-1">
+              <Label class="text-xs font-medium">{{ t('diff.generatedSql') }}</Label>
+              <textarea
+                v-model="syncSql"
+                class="w-full h-48 rounded-lg border bg-muted/20 p-3 font-mono text-xs resize-none focus:outline-none focus:ring-1 focus:ring-ring"
+              />
+            </div>
+          </template>
+        </template>
+      </div>
+
+      <DialogFooter v-if="step === 'result' && diffs.length > 0" class="flex items-center gap-2">
+        <Button variant="outline" size="sm" @click="copySql">
+          <Copy class="w-3 h-3 mr-1" /> {{ t('diff.copySql') }}
+        </Button>
+        <Button size="sm" :disabled="!syncSql.trim() || executing" @click="executeSql">
+          <Loader2 v-if="executing" class="w-3 h-3 animate-spin mr-1" />
+          <Play v-else class="w-3 h-3 mr-1" />
+          {{ t('diff.executeSync') }}
+        </Button>
+      </DialogFooter>
+    </DialogContent>
+  </Dialog>
+</template>
diff --git a/src/components/sidebar/TreeItem.vue b/src/components/sidebar/TreeItem.vue
index f1ed847439..2b40954bd4 100644
--- a/src/components/sidebar/TreeItem.vue
+++ b/src/components/sidebar/TreeItem.vue
@@ -324,6 +324,15 @@ function openTransfer() {
   }
 }
 
+function openSchemaDiff() {
+  if (props.node.connectionId) {
+    connectionStore.schemaDiffSource = {
+      connectionId: props.node.connectionId,
+      database: props.node.database ?? "",
+    };
+  }
+}
+
 const canExpand = !leafTypes.has(props.node.type);
 const canPin = computed(() => pinnableTypes.has(props.node.type));
 const isPinned = computed(() => props.node.pinned || connectionStore.isTreeNodePinned(props.node.id));
@@ -459,6 +468,9 @@ async function showMore() {
         <ContextMenuItem @click="openTransfer">
           <ArrowRightLeft class="w-4 h-4" /> {{ t('transfer.dataTransfer') }}
         </ContextMenuItem>
+        <ContextMenuItem @click="openSchemaDiff">
+          <ArrowRightLeft class="w-4 h-4" /> {{ t('diff.title') }}
+        </ContextMenuItem>
       </template>
 
       <template v-if="node.type === 'table' || node.type === 'view'">
diff --git a/src/i18n/locales/en.ts b/src/i18n/locales/en.ts
index bdef4d44e9..e0258cb153 100644
--- a/src/i18n/locales/en.ts
+++ b/src/i18n/locales/en.ts
@@ -295,4 +295,26 @@ export default {
     overallProgress: "Overall progress",
     dataTransfer: "Data Transfer",
   },
+  diff: {
+    title: "Compare Databases",
+    source: "Source",
+    target: "Target",
+    selectConnection: "Select connection",
+    selectDatabase: "Select database",
+    compare: "Compare",
+    comparing: "Comparing schemas...",
+    noDifferences: "No differences found",
+    table: "Table",
+    status: "Status",
+    details: "Details",
+    added: "Added",
+    removed: "Removed",
+    modified: "Modified",
+    newTable: "New table",
+    dropTable: "Drop table",
+    generatedSql: "Sync SQL",
+    copySql: "Copy SQL",
+    executeSync: "Execute Sync",
+    syncSuccess: "Sync executed successfully",
+  },
 };
diff --git a/src/i18n/locales/zh-CN.ts b/src/i18n/locales/zh-CN.ts
index 48a0fb0609..ace0e0ebf5 100644
--- a/src/i18n/locales/zh-CN.ts
+++ b/src/i18n/locales/zh-CN.ts
@@ -300,4 +300,26 @@ export default {
     overallProgress: "整体进度",
     dataTransfer: "数据传输",
   },
+  diff: {
+    title: "比较数据库",
+    source: "源数据库",
+    target: "目标数据库",
+    selectConnection: "选择连接",
+    selectDatabase: "选择数据库",
+    compare: "开始比较",
+    comparing: "正在比较结构...",
+    noDifferences: "两个数据库结构完全一致",
+    table: "表名",
+    status: "状态",
+    details: "详情",
+    added: "新增",
+    removed: "删除",
+    modified: "修改",
+    newTable: "新增表",
+    dropTable: "删除表",
+    generatedSql: "同步 SQL",
+    copySql: "复制 SQL",
+    executeSync: "执行同步",
+    syncSuccess: "同步执行成功",
+  },
 };
diff --git a/src/lib/schemaDiff.ts b/src/lib/schemaDiff.ts
new file mode 100644
index 0000000000..44ec2761db
--- /dev/null
+++ b/src/lib/schemaDiff.ts
@@ -0,0 +1,210 @@
+import type { ColumnInfo, IndexInfo, DatabaseType } from "@/types/database";
+
+export interface ColumnDiff {
+  type: "added" | "removed" | "modified";
+  name: string;
+  source?: ColumnInfo;
+  target?: ColumnInfo;
+  changes?: string[];
+}
+
+export interface IndexDiff {
+  type: "added" | "removed";
+  name: string;
+  source?: IndexInfo;
+  target?: IndexInfo;
+}
+
+export interface TableDiff {
+  type: "added" | "removed" | "modified";
+  name: string;
+  columns?: ColumnDiff[];
+  indexes?: IndexDiff[];
+  ddl?: string;
+}
+
+export function diffColumns(
+  source: ColumnInfo[],
+  target: ColumnInfo[],
+): ColumnDiff[] {
+  const diffs: ColumnDiff[] = [];
+  const targetMap = new Map(target.map((c) => [c.name, c]));
+  const sourceMap = new Map(source.map((c) => [c.name, c]));
+
+  for (const sc of source) {
+    const tc = targetMap.get(sc.name);
+    if (!tc) {
+      diffs.push({ type: "added", name: sc.name, source: sc });
+    } else {
+      const changes: string[] = [];
+      if (sc.data_type.toLowerCase() !== tc.data_type.toLowerCase()) {
+        changes.push(`type: ${tc.data_type} → ${sc.data_type}`);
+      }
+      if (sc.is_nullable !== tc.is_nullable) {
+        changes.push(`nullable: ${tc.is_nullable ? "YES" : "NO"} → ${sc.is_nullable ? "YES" : "NO"}`);
+      }
+      if ((sc.column_default ?? "") !== (tc.column_default ?? "")) {
+        changes.push(`default: ${tc.column_default ?? "NULL"} → ${sc.column_default ?? "NULL"}`);
+      }
+      if (changes.length > 0) {
+        diffs.push({ type: "modified", name: sc.name, source: sc, target: tc, changes });
+      }
+    }
+  }
+
+  for (const tc of target) {
+    if (!sourceMap.has(tc.name)) {
+      diffs.push({ type: "removed", name: tc.name, target: tc });
+    }
+  }
+
+  return diffs;
+}
+
+export function diffIndexes(
+  source: IndexInfo[],
+  target: IndexInfo[],
+): IndexDiff[] {
+  const diffs: IndexDiff[] = [];
+  const targetMap = new Map(target.map((i) => [i.name, i]));
+  const sourceMap = new Map(source.map((i) => [i.name, i]));
+
+  for (const si of source) {
+    if (si.is_primary) continue;
+    if (!targetMap.has(si.name)) {
+      diffs.push({ type: "added", name: si.name, source: si });
+    }
+  }
+
+  for (const ti of target) {
+    if (ti.is_primary) continue;
+    if (!sourceMap.has(ti.name)) {
+      diffs.push({ type: "removed", name: ti.name, target: ti });
+    }
+  }
+
+  return diffs;
+}
+
+export function diffTables(
+  sourceTables: string[],
+  targetTables: string[],
+): { added: string[]; removed: string[]; common: string[] } {
+  const targetSet = new Set(targetTables);
+  const sourceSet = new Set(sourceTables);
+  return {
+    added: sourceTables.filter((t) => !targetSet.has(t)),
+    removed: targetTables.filter((t) => !sourceSet.has(t)),
+    common: sourceTables.filter((t) => targetSet.has(t)),
+  };
+}
+
+function quoteId(name: string, dbType: DatabaseType): string {
+  if (dbType === "mysql" || dbType === "doris" || dbType === "starrocks") {
+    return `\`${name.replace(/`/g, "``")}\``;
+  }
+  return `"${name.replace(/"/g, '""')}"`;
+}
+
+function columnDef(col: ColumnInfo, dbType: DatabaseType): string {
+  let def = `${quoteId(col.name, dbType)} ${col.data_type}`;
+  if (!col.is_nullable) def += " NOT NULL";
+  if (col.column_default !== null && col.column_default !== undefined) {
+    def += ` DEFAULT ${col.column_default}`;
+  }
+  return def;
+}
+
+export function generateSyncSql(
+  diffs: TableDiff[],
+  dbType: DatabaseType,
+): string {
+  const lines: string[] = [];
+  const isMySQL = dbType === "mysql" || dbType === "doris" || dbType === "starrocks";
+
+  for (const diff of diffs) {
+    const qt = quoteId(diff.name, dbType);
+
+    if (diff.type === "added" && diff.ddl) {
+      lines.push(`-- Create table: ${diff.name}`);
+      lines.push(diff.ddl + ";");
+      lines.push("");
+      continue;
+    }
+
+    if (diff.type === "removed") {
+      lines.push(`-- Drop table: ${diff.name}`);
+      lines.push(`DROP TABLE IF EXISTS ${qt};`);
+      lines.push("");
+      continue;
+    }
+
+    if (diff.type === "modified") {
+      const parts: string[] = [];
+
+      if (diff.columns) {
+        for (const col of diff.columns) {
+          if (col.type === "added" && col.source) {
+            parts.push(`  ADD COLUMN ${columnDef(col.source, dbType)}`);
+          } else if (col.type === "removed") {
+            parts.push(`  DROP COLUMN ${quoteId(col.name, dbType)}`);
+          } else if (col.type === "modified" && col.source) {
+            if (isMySQL) {
+              parts.push(`  MODIFY COLUMN ${columnDef(col.source, dbType)}`);
+            } else {
+              const qn = quoteId(col.name, dbType);
+              if (col.changes?.some((c) => c.startsWith("type:"))) {
+                parts.push(`  ALTER COLUMN ${qn} TYPE ${col.source.data_type}`);
+              }
+              if (col.changes?.some((c) => c.startsWith("nullable:"))) {
+                parts.push(
+                  col.source.is_nullable
+                    ? `  ALTER COLUMN ${qn} DROP NOT NULL`
+                    : `  ALTER COLUMN ${qn} SET NOT NULL`,
+                );
+              }
+              if (col.changes?.some((c) => c.startsWith("default:"))) {
+                if (col.source.column_default !== null && col.source.column_default !== undefined) {
+                  parts.push(`  ALTER COLUMN ${qn} SET DEFAULT ${col.source.column_default}`);
+                } else {
+                  parts.push(`  ALTER COLUMN ${qn} DROP DEFAULT`);
+                }
+              }
+            }
+          }
+        }
+      }
+
+      if (diff.indexes) {
+        for (const idx of diff.indexes) {
+          if (idx.type === "added" && idx.source) {
+            const cols = idx.source.columns.map((c) => quoteId(c, dbType)).join(", ");
+            const unique = idx.source.is_unique ? "UNIQUE " : "";
+            lines.push(`CREATE ${unique}INDEX ${quoteId(idx.name, dbType)} ON ${qt} (${cols});`);
+          } else if (idx.type === "removed") {
+            if (isMySQL) {
+              lines.push(`DROP INDEX ${quoteId(idx.name, dbType)} ON ${qt};`);
+            } else {
+              lines.push(`DROP INDEX IF EXISTS ${quoteId(idx.name, dbType)};`);
+            }
+          }
+        }
+      }
+
+      if (parts.length > 0) {
+        lines.push(`-- Alter table: ${diff.name}`);
+        if (isMySQL) {
+          lines.push(`ALTER TABLE ${qt}`);
+          lines.push(parts.join(",\n") + ";");
+        } else {
+          for (const part of parts) {
+            lines.push(`ALTER TABLE ${qt}${part};`);
+          }
+        }
+        lines.push("");
+      }
+    }
+  }
+
+  return lines.join("\n").trim();
+}
diff --git a/src/stores/connectionStore.ts b/src/stores/connectionStore.ts
index ddbb172f32..9764d5e567 100644
--- a/src/stores/connectionStore.ts
+++ b/src/stores/connectionStore.ts
@@ -17,6 +17,7 @@ export const useConnectionStore = defineStore("connection", () => {
   const completionTablesCache = ref<Record<string, SqlCompletionTable[]>>({});
   const completionColumnsCache = ref<Record<string, ColumnInfo[]>>({});
   const transferSource = ref<{ connectionId: string; database: string } | null>(null);
+  const schemaDiffSource = ref<{ connectionId: string; database: string } | null>(null);
 
   function startEditing(id: string) {
     editingConnectionId.value = id;
@@ -645,5 +646,6 @@ export const useConnectionStore = defineStore("connection", () => {
     exportConnectionsToFile,
     importConnectionsFromFile,
     transferSource,
+    schemaDiffSource,
   };
 });