update docs

Signed-off-by: NAnnie_wang <annie.wangli@huawei.com>

en/application-dev/reference/apis/js-apis-data-storage.md

@@ -22,10 +22,10 @@ import data_storage from '@ohos.data.storage';
 
 **System capability**: SystemCapability.DistributedDataManager.Preferences.Core
 
-| Name             | Type   | Readable | Writable | Description                                                 |
-| ---------------- | ------ | -------- | -------- | ----------------------------------------------------------- |
-| MAX_KEY_LENGTH   | string | Yes      | No       | Maximum length of a key. It must be less than 80 bytes.     |
-| MAX_VALUE_LENGTH | string | Yes      | No       | Maximum length of a value. It must be less than 8192 bytes. |
+| Name            | Type| Readable| Writable| Description                                 |
+| ---------------- | -------- | ---- | ---- | ------------------------------------- |
+| MAX_KEY_LENGTH   | number   | Yes  | No  | Maximum length of a key. It must be less than 80 bytes.    |
+| MAX_VALUE_LENGTH | number   | Yes  | No  | Maximum length of a value. It must be less than 8192 bytes.|
 
 
 ## data_storage.getStorageSync
@@ -53,8 +53,8 @@ Reads the specified file and loads its data to the **Storage** instance for data
 ```js
 import featureAbility from '@ohos.ability.featureAbility';
 
-var path;
-var context = featureAbility.getContext();
+let path;
+let context = featureAbility.getContext();
 context.getFilesDir().then((filePath) => {
   path = filePath;
   console.info("======================>getFilesDirPromise====================>");
@@ -86,8 +86,8 @@ Reads the specified file and loads its data to the **Storage** instance for data
 ```js
 import featureAbility from '@ohos.ability.featureAbility';
 
-var path;
-var context = featureAbility.getContext();
+let path;
+let context = featureAbility.getContext();
 context.getFilesDir().then((filePath) => {
   path = filePath;
   console.info("======================>getFilesDirPromise====================>");
@@ -129,8 +129,8 @@ Reads the specified file and loads its data to the **Storage** instance for data
 ```js
 import featureAbility from '@ohos.ability.featureAbility';
 
-var path;
-var context = featureAbility.getContext();
+let path;
+let context = featureAbility.getContext();
 context.getFilesDir().then((filePath) => {
   path = filePath;
   console.info("======================>getFilesDirPromise====================>");
@@ -165,8 +165,8 @@ Deletes the singleton **Storage** instance of a file from the memory, and delete
 ```js
 import featureAbility from '@ohos.ability.featureAbility';
 
-var path;
-var context = featureAbility.getContext();
+let path;
+let context = featureAbility.getContext();
 context.getFilesDir().then((filePath) => {
     path = filePath;
     console.info("======================>getFilesDirPromise====================>");
@@ -195,8 +195,8 @@ Deletes the singleton **Storage** instance of a file from the memory, and delete
 ```js
 import featureAbility from '@ohos.ability.featureAbility';
 
-var path;
-var context = featureAbility.getContext();
+let path;
+let context = featureAbility.getContext();
 context.getFilesDir().then((filePath) => {
   path = filePath;
   console.info("======================>getFilesDirPromise====================>");
@@ -237,8 +237,8 @@ Deletes the singleton **Storage** instance of a file from the memory, and delete
 ```js
 import featureAbility from '@ohos.ability.featureAbility';
 
-var path;
-var context = featureAbility.getContext();
+let path;
+let context = featureAbility.getContext();
 context.getFilesDir().then((filePath) => {
   path = filePath;
   console.info("======================>getFilesDirPromise====================>");
@@ -271,8 +271,8 @@ Removes the singleton **Storage** instance of a file from the cache. The removed
 ```js
 import featureAbility from '@ohos.ability.featureAbility';
 
-var path;
-var context = featureAbility.getContext();
+let path;
+let context = featureAbility.getContext();
 context.getFilesDir().then((filePath) => {
     path = filePath;
     console.info("======================>getFilesDirPromise====================>");
@@ -302,8 +302,8 @@ Removes the singleton **Storage** instance of a file from the cache. The removed
 ```js
 import featureAbility from '@ohos.ability.featureAbility';
 
-var path;
-var context = featureAbility.getContext();
+let path;
+let context = featureAbility.getContext();
 context.getFilesDir().then((filePath) => {
   path = filePath;
   console.info("======================>getFilesDirPromise====================>");
@@ -344,8 +344,8 @@ Removes the singleton **Storage** instance of a file from the cache. The removed
 ```js
 import featureAbility from '@ohos.ability.featureAbility';
 
-var path;
-var context = featureAbility.getContext();
+let path;
+let context = featureAbility.getContext();
 context.getFilesDir().then((filePath) => {
   path = filePath;
   console.info("======================>getFilesDirPromise====================>");
@@ -864,15 +864,15 @@ Subscribes to data changes. The **StorageObserver** needs to be implemented. Whe
 
 **Parameters**
 
-| Name  | Type                                               | Description                                    |
-| -------- | --------------------------------------------------- | ---------------------------------------- |
-| type     | string                                              | Event type. The value **change** indicates data change events.|
-| callback | Callback<[StorageObserver](#storageobserver)> | Callback used to return data changes.                          |
+| Name  | Type                                               |  Mandatory| Description                                    |
+| -------- | --------------------------------------------------- | ------ |---------------------------------------- |
+| type     | string                                              |Yes| Event type. The value **change** indicates data change events.|
+| callback | Callback<[StorageObserver](#storageobserver)> | Yes|Callback used to return data changes.                          |
 
 **Example**
 
 ```js
-var observer = function (key) {
+let observer = function (key) {
     console.info("The key of " + key + " changed.");
 }
 storage.on('change', observer);
@@ -891,15 +891,15 @@ Unsubscribes from data changes.
 
 **Parameters**
 
-| Name  | Type                                               | Description                                    |
-| -------- | --------------------------------------------------- | ---------------------------------------- |
-| type     | string                                              | Event type. The value **change** indicates data change events.|
-| callback | Callback<[StorageObserver](#storageobserver)> | Callback used to return data changes.                |
+| Name  | Type                                               | Mandatory|  Description                                |
+| -------- | --------------------------------------------------- | ------ |---------------------------------------- |
+| type     | string                                              |Yes| Event type. The value **change** indicates data change events.|
+| callback | Callback<[StorageObserver](#storageobserver)> | Yes|Callback used to return data changes.                |
 
 **Example**
 
 ```js
-var observer = function (key) {
+let observer = function (key) {
     console.info("The key of " + key + " changed.");
 }
 storage.off('change', observer);

en/application-dev/reference/errorcodes/errorcode-data-rdb.md

+# RDB Error Codes
+
+## 14800010 Invalid RDB Name
+
+**Error Message**
+
+Invalid database name.
+
+**Description**
+
+The RDB store name is invalid.
+
+**Possible Causes**
+
+The RDB store name is empty or exceeds 1024 bytes.
+
+**Solution**
+
+Check that the RDB store name is not empty and does not exceed 1024 bytes.
+
+## 14800011 Database File Corrupted
+
+**Error Message**
+
+Database corrupted.
+
+**Description**
+
+The RDB store is corrupted when an API for adding, deleting, querying, or synchronizing data is invoked.
+
+**Possible Causes**
+
+The RDB store file has been corrupted.
+
+**Solution**
+
+1. Restore the RDB store using the backup file.
+2. If no RDB backup file is available, delete the RDB store and create it again.
+
+## 14800012 Empty Result Set or Invalid Position
+
+**Error Message**
+
+The result set is empty or the specified location is invalid.
+
+**Description**
+
+The result set is empty or the specified location is invalid.
+
+**Possible Causes**
+
+The result set is empty, or the specified row number in the result set is out of range [0, m - 1]. **m** is **resultsetV9.rowCount**.
+
+**Solution**
+
+Check whether the result set is empty or whether the specified row number is out of range.
+
+## 14800013 Null Column Value or Column Data Type Incompatible With the API Called
+
+**Error Message**
+
+The column value is null or the column type is incompatible.
+
+**Description**
+
+The column value is null, or the column data type is incompatible with the API called.
+
+**Possible Causes**
+
+1. The result set is empty.
+2. The current row number in the result set is out of range [0, m - 1]. **m** is **resultsetV9.rowCount**.
+3. The column number is out of the range [0, n - 1]. **n** is **resultsetV9.columnCount**.
+4. The API called does not support the type of the column data.
+
+**Solution**
+
+1. Check whether the result set is empty.
+2. Check whether the row number and column number of the result set are out of range.
+3. Check whether the column data type is supported.

en/application-dev/reference/errorcodes/errorcode-preferences.md

+# Preferences Error Codes
+
+## 15500010 Failed to Delete Preferences
+**Error Message**
+
+Failed to delete preferences.
+
+**Description**
+
+Failed to delete the preference.
+
+**Possible Causes**
+
+The possible causes are as follows:
+1. The file name is incorrect.
+2. The file path is incorrect.
+
+**Solution**
+
+1. Check that the file name is correct.
+2. Check that the file path is correct.