update en/application-dev/database/database-mdds-guidelines.md.

Signed-off-by: N@ge-yafang <geyafang@huawei.com>

en/application-dev/database/database-mdds-guidelines.md

@@ -77,7 +77,7 @@ The following uses a single KV store as an example to describe the development p
 
 1.  Import the distributed database module.
 
-    ```
+    ```js
     import distributedData from '@ohos.data.distributedData';
     ```
 
@@ -88,7 +88,7 @@ The following uses a single KV store as an example to describe the development p
 
     The sample code is as follows:
 
-    ```
+    ```js
     let kvManager;
     try {
         const kvManagerConfig = {
@@ -118,7 +118,7 @@ The following uses a single KV store as an example to describe the development p
 
     The sample code is as follows:
 
-    ```
+    ```js
     let kvStore;
     try {
         const options = {
@@ -149,7 +149,7 @@ The following uses a single KV store as an example to describe the development p
 
     The following is the sample code for subscribing to the data changes of a single KV store:
 
-    ```
+    ```js
     kvStore.on('dataChange', distributedData.SubscribeType.SUBSCRIBE_TYPE_ALL, function (data) {
         console.log("dataChange callback call data: " + JSON.stringify(data));
     });
@@ -162,7 +162,7 @@ The following uses a single KV store as an example to describe the development p
 
     The following is the sample code for writing key-value pairs of the string type into the single KV store:
 
-    ```
+    ```js
     const KEY_TEST_STRING_ELEMENT = 'key_test_string';
     const VALUE_TEST_STRING_ELEMENT = 'value-test-string';
     try {
@@ -185,7 +185,7 @@ The following uses a single KV store as an example to describe the development p
 
     The following is the sample code for querying data of the string type from the single KV store:
 
-    ```
+    ```js
     const KEY_TEST_STRING_ELEMENT = 'key_test_string';
     const VALUE_TEST_STRING_ELEMENT = 'value-test-string';
     try {
@@ -210,7 +210,7 @@ The following uses a single KV store as an example to describe the development p
 
     The following is the sample code for data synchronization in a single KV store.  **deviceIds**  can be obtained by deviceManager by calling  **getTrustedDeviceListSync\(\)**, and  **1000**  indicates that the maximum delay time is 1000 ms.
 
-    ```
+    ```js
     import deviceManager from '@ohos.distributedHardware.deviceManager';
     
     let devManager;
@@ -231,5 +231,3 @@ The following uses a single KV store as an example to describe the development p
     }
     kvStore.sync(deviceIds, distributedData.SyncMode.PUSH_ONLY, 1000);
     ```
-
-