IndexedDB - 刪除資料

有很多情況下，我們需要從資料庫中刪除資料；可能是出於儲存目的或者僅僅刪除不需要的資料以釋放空間。如果我們希望從資料庫中刪除這些不必要的資料，可以使用 .delete() 函式

語法

const request = objectStore.delete(data);

我們使用 delete() 函式刪除資料庫中不再需要的資料欄位。

示例

我們來看一個用於刪除資料的示例指令碼 −

<!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 deletename = store.delete(1);
         deletename.onsuccess = function(){
            document.write("id : 1 has been deleted");
         }
         transaction.oncomplete = function(){
            db.close;
         }
      }
   </script>
</body>
</html>

輸出

database opened successfully
id : 1 has been deleted

刪除 id:1 後資料庫 =

0  2
{id: 2, name: 'praneeth', branch: 'CSE'}
1  3
{id: 3, name: 'palli', branch: 'EEE'}
2  4
{id: 4, name: 'deevana', branch: 'CSE'}

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