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。
After we created the data, the next step is to perform various operations on it; so we need to update the data regularly. We also need to update the data in the case where we entered data incorrectly into the database. Here, we have to specify a read−write transaction because we want to write to the database, not just read from it.
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。
If we want to modify it or make an entry which is already present in the database we use the put() function.
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。
We use the put() function on the object store for which the transaction happened and we need to update data.
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 -
Let us look at the script below to understand how to update or modify the data in objectstore using put() function −
<!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>