javascript 使用javascript从web sql中的结果集中删除行
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delete row from result set in web sql with javascript
提问by Kaijin
I understand that the result set from web sql isn't quite an array, more of an object? I'm cycling through a result set and to speed things up I'd like to remove a row once it's been found. I've tried "delete" and "splice", the former does nothing and the latter throws an error. Here's a piece of what I'm trying to do, notice the delete on line 18:
我知道来自 web sql 的结果集不是一个数组，更像是一个对象？我正在循环查看结果集，为了加快速度，我想在找到一行后将其删除。我试过“删除”和“拼接”，前者什么都不做，后者抛出一个错误。这是我正在尝试做的一部分，注意第 18 行的删除：
function selectFromReverse(reverseRay,suggRay){
var reverseString = reverseRay.toString();
db.transaction(function (tx) {
tx.executeSql('SELECT votecount, comboid FROM counterCombos WHERE comboid IN ('+reverseString+') AND votecount>0', [], function(tx, results){
processSelectFromReverse(results,suggRay);
});
}, function(){onError});
}
function processSelectFromReverse(results,suggRay){
var i = suggRay.length;
while(i--){
var j = results.rows.length;
while(j--){
console.log('searching');
var found = 0;
if(suggRay[i].reverse == results.rows.item(j).comboid){
delete results.rows.item(j);
console.log('found');
found++;
break;
}
}
if(found == 0){
console.log('lost');
}
}
}
回答by Kyaw Tun
Actually you use DELETE sql command to delete the record from the database. For example:
实际上您使用 DELETE sql 命令从数据库中删除记录。例如：
tx.executeSql('DELETE FROM counterCombos WHERE comboid = ?', [comboid], success, error);
processSelectFromReversecould modified to include txas input like
processSelectFromReverse可以修改为包括tx作为输入
processSelectFromReverse(results,suggRay,tx)
回答by Ryan
Web SQL has been dropped from the HTML5 workupfor almost 2 years now and isn't supported. Web Storageand Indexed DBhave taken its place.
Web SQL 已从 HTML5 工作中删除近 2 年，并且不受支持。Web Storage和Indexed DB已经取而代之。
Your syntax for deleting objects: delete object;is correct. It's not used often in JavaScript but I have used it and that is the correct usage.
您删除对象的语法：delete object;是正确的。它在 JavaScript 中并不经常使用，但我已经使用过它，这是正确的用法。
Using web-storage (more commonly called local storage) you would instansiate a localStorageobject which comes with the method removeItem(item key), already built in.
使用网络存储（通常称为本地存储），您可以实例化一个localStorage对象，该对象removeItem(item key)已经内置。
You can see more at the above link on webstorage or go here for a tutorial.
您可以在上面的 webstorage 链接中查看更多信息，或者到这里查看教程。
回答by arielf
If your concern is IOS or Android, making an application that is wrapped natively would allow you to create a javascript interface. From this interface you can access (for android) sqlite and create a nice, query0able solution. The downside is this would require people downloading your application rather then accessing a site.
如果您关心的是 IOS 或 Android，那么制作一个原生包装的应用程序将允许您创建一个 javascript 界面。从这个界面你可以访问（对于安卓）sqlite 并创建一个很好的、可查询的解决方案。缺点是这需要人们下载您的应用程序而不是访问站点。
indexeddb support is growing rather slowly. With a proper coding style you could probably use local storage (as mentioned in the above comments) with pretty respectable speeds.
indexeddb 支持增长相当缓慢。通过适当的编码风格，您可能可以以相当可观的速度使用本地存储（如上述评论中所述）。
