Indexeddb 简明教程

IndexedDB - Updating Data

创建数据后，下一步是执行各种操作；因此，我们需要定期更新数据。在数据库中输入数据不正确的情况下，还需要更新数据。在这里，我们必须指定一个读写事务，因为我们希望写入数据库，而不仅仅是从数据库中读取。

如果我们要修改或进行数据库中已存在的条目，我们将使用 put() 函数。

Syntax

var requestUpdate = objectStore.put(data);

我们对事务发生的对象存储使用 put() 函数，并且我们需要更新数据。

Example

让我们看下面的脚本，以了解如何使用 put() 函数更新或修改 objectstore 中的数据 -

<!DOCTYPE html>
<html lang="en">
<head>
   <title>Document</title>
</head>
<body>
   <script>
      const request = indexedDB.open("botdatabase",1);
      request.onupgradeneeded = function(){
         const db = request.result;
         const store = db.createObjectStore("bots",{ keyPath: "id"});
      }
      request.onsuccess = function(){
         document.write("database opened successfully");
         const db = request.result;
         const transaction=db.transaction("bots","readwrite");
         const store = transaction.objectStore("bots");
         store.add({id: 1, name: "jason",branch: "IT"});
         store.add({id: 2, name: "praneeth",branch: "CSE"});
         store.add({id: 3, name: "palli",branch: "EEE"});
         store.add({id: 4, name: "abdul",branch: "IT"});
         store.put({id: 4, name: "deevana",branch: "CSE"});
         const idquery = store.get(4);
         idquery.onsuccess = function(){
            document.write("idquery",idquery.result);
         }
         transaction.oncomplete = function(){
            db.close;
         }
      }
   </script>
</body>
</html>

Output

database opened successfully
idquery {id: 4, name: 'deevana', branch: 'CSE'}
Previously the data stored in id: 4 was
Name: abdul Branch : IT
But as we updated the entry the values are changed.