Web SQL 的使用

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    <title>Document</title>
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    <div id="content"></div>
    <script>
        // 返回数据库的实例
        var db = openDatabase('mydb', '1.0', 'Test DB', 2 * 1024 * 1024)
        // 实例上调用方法，接收一个回调函数
        db.transaction(function (tx) {
            //tx 是一个SQLTransaction对象，后面的所有操作都基于该对象。
            //创建表格
            tx.executeSql('CREATE TABLE IF NOT EXISTS STU(stuId unique,stuName)')
            //插入字段
            tx.executeSql(`INSERT INTO STU(stuId,stuName) values(111,222`)
            tx.executeSql(`INSERT INTO STU(stuId,stuName) values(${Math.random()},${Math.random()})`)
            tx.executeSql(`INSERT INTO STU(stuId,stuName) values(${Math.random()},${Math.random()})`)
            tx.executeSql(`INSERT INTO STU(stuId,stuName) values(${Math.random()},${Math.random()})`)
            tx.executeSql(`INSERT INTO STU(stuId,stuName) values(${Math.random()},${Math.random()})`)
            tx.executeSql(`INSERT INTO STU(stuId,stuName) values(${Math.random()},${Math.random()})`)
            tx.executeSql(`INSERT INTO STU(stuId,stuName) values(${Math.random()},${Math.random()})`)
            tx.executeSql(`INSERT INTO STU(stuId,stuName) values(${Math.random()},${Math.random()})`)
            tx.executeSql(`INSERT INTO STU(stuId,stuName) values(${Math.random()},${Math.random()})`)
        })
        // 查询
        db.transaction(function (tx) {
            tx.executeSql('SELECT * FROM STU', [], function (tx, result) {
                console.log(result.rows) //拿到数据
                msg = `<p>查询到的数据条数一共有:${result.rows.length}条</p>`
                content.innerHTML += msg
                for (var i = 0; i < result.rows.length; i++) {
                    msg = `<p><b>${result.rows.item(i).stuName}</b></p>`
                    content.innerHTML += msg
                }
            }, null)
        })

        // 删除数据
        db.transaction(function (tx) {
            tx.executeSql('DELETE FROM STU WHERE stuId=?', [111])
        })

        // 修改数据
        db.transaction(function (tx) {
            tx.executeSql('UPDATE STU SET stuName=? WHERE stuId=2', ["寒冰"])
        })
	 </script>
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