如何在 Cordova 中压缩 SQL 指令? [英] How to compact SQL instructions in Cordova?

问题描述

我正在制作一个将使用数据库的小应用程序，我想知道如何转换它:

I'm making a tiny app that will use Databases, I want to know how to convert this:

function testDB()
{
    var db = window.openDatabase("Database", "1.0", "mydatabase", 2000000);
    db.transaction(queryNames, errorDB);
}
function queryNames(tx) 
{
    tx.executeSql('SELECT name FROM people WHERE id=13', [], listNames, errorDB);
}
function listNames(tx, results) 
{
    for (var i=0;i<results.rows.length;i++)
    {
        alert(results.rows.item(i).name);
    }
}
function errorDB(err)
{
    alert("Fatal error");
}

这样的事情(如果可能更紧凑):

To something like this (either if it is possible more compacted):

function testDB()
{
    var db = window.openDatabase("Database", "1.0", "mydatabase", 2000000);
    db.transaction(queryNames('SELECT name FROM people WHERE id=13'), errorDB);
}
function queryNames(tx, query) 
{
    tx.executeSql(, [], 
    function listNames(tx, results) 
    {
        for (var i=0;i<results.rows.length;i++)
        {
            alert(results.rows.item(i).name);
        }
    },
    errorDB);
}
function errorDB(err)
{
    alert("Fatal error");
}

简而言之，我正在尝试回收"代码.感谢阅读.

In few words, I'm trying to "recycle" the code. Thanks for reading.

推荐答案

SQLite 调用是一个事件.我使用 jQuery 创建了以下函数(该函数也在控制台中记录结果，因此您需要控制台插件才能工作):

The SQLite call is an event. I have created the following function by using jQuery (The function is also logging the results in the console, so you need the console plugin for working):

var db = window.openDatabase("Database", "1.0", "mydatabase", 2000000);

function queryDB(query) {

    var start    = Date.now();
    var deferred = $.Deferred();
    db.transaction(function (tx) {
        tx.executeSql(query, [], function (tx, results) {
            console.log("Rows: " + results.rows.length + " Time: " + (Date.now() - start) + "ms Query: " + query);
            deferred.resolve(results);
        }, function (error) {
            console.log("Error processing SQL: " + error.code + " " + error.no + " Query: " + query);
        });
    }, function (error) {
        console.log("Transaction Error: " + error.code + " " + error.no + " Query: " + query);
    });
    return deferred.promise();
}

函数调用是:

$.when(queryDB("SELECT * FROM table")).done(function (results) {
        // Here your logic with the results
});

这种方式的好处是，可以同时调用多个查询:

The advantage of this way is, that you can call multiple queries the same time:

$.when(queryDB("SELECT * FROM table1"), queryDB("SELECT * FROM table2")).done(function (results1, results2) {
        // Here your logic with the results
});

这篇关于如何在 Cordova 中压缩 SQL 指令?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！