function openDB(dbname, version = 1) {
    return new Promise((resolve, reject) => {
        // 兼容浏览器
        var indexedDB =
            window.indexedDB ||
            window.mozIndexedDB ||
            window.webkitIndexedDB ||
            window.msIndexedDB;
        let db;
        // 打开数据库,若没有就会创建
        const request = indexedDB.open(dbname, version);
        // 数据库打开成功回调
        request.onsuccess = function (event) {
            db = event.target.result;   // 数据库对象
            console.log("数据库打开成功");
            resolve(db);
        };
        // 数据库打开失败的回调
        request.onerror = function (event) {
            console.log("数据库打开失败");
        };
        // 数据库有更新的时候的回调
        request.onupgradeneeded = function (event) {
            // 数据库创建或升级的时候回调
            console.log("onupgradeneeded");
            db = event.target.result;
            var objectStore;
            // 创建数据库
            objectStore = db.createObjectStore("user", {
                keyPath: "uuid",  // 主键
                autoIncrement: true,    // 自增
            });
            // 创建索引，在后面查询数据的时候可以根据索引查
            objectStore.createIndex("uuid", "uuid", {unique: true});
            objectStore.createIndex("name", "name", {unique: false});
            objectStore.createIndex("age", "age", {unique: false});
        }
    })
}

// 插入数据
function addData(db, storeName, data) {
    var request = db
        .transaction([storeName], "readwrite")   // 事务对象，指定表格名称和操作的模式（“只读”或“读写”）
        .objectStore(storeName)     // 创建对象
        .add(data);
    request.onsuccess = function (event) {
        console.log("数据写入成功");
    }
    request.onerror = function (event) {
        console.log("数据写入失败");
    }
}

// 通过主键查询数据
function getDataByKey(db, storeName, key) {
    var transaction = db.transaction([storeName]);  // 声明事务
    var objectStore = transaction.objectStore(storeName);   // 仓库对象
    var request = objectStore.get(key);     // 通过主键获取数据  getAll 查询所有数据

    request.onerror = function (event) {
        console.log("事务失败")
    };

    request.onsuccess = function (event) {
        console.log("主键查询结果：", request.result);
    }
}

// 通过游标查询数据
function cursorGetData(db, storeName) {
    let list = [];
    var store = db
        .transaction(storeName,"readwrite")     // 事务
        .objectStore(storeName);    // 仓库对象
    var request = store.openCursor();   // 指针对象
    // 游标开启成功，逐行读取数据
    request.onsuccess = function (e) {
        var cursor = e.target.result;
        if (cursor){
            // 必须要检查
            list.push(cursor.value);
            cursor.continue();  // 遍历存储对象中的所有内容
        }else {
            console.log("游标读取的数据：",list);
        }
    };
}

// 通过索引查询数据
function getDataByIndex(db,storeName,indexName,indexValue) {
    var store = db.transaction(storeName,"readwrite").objectStore(storeName);
    var request = store.index(indexName).get(indexValue);
    request.onerror = function (){
        console.log("事务失败")
    };
    request.onsuccess = function (e) {
        var result = e.target.result;
        console.log("索引插叙结果：",result);
    };
}

// 通过索引和游标查询数据
function cursorGetDataByIndex(db, storeName, indexName, indexValue) {
    let list = [];
    var store = db.transaction(storeName,"readwrite").objectStore(storeName);
    var request = store
        .index(indexName)   // 索引对象
        .openCursor(IDBKeyRange.only(indexValue));  // 指针对象
    request.onsuccess = function (e) {
        var cursor = e.target.result;
        if (cursor){
            // 必须检查
            list.push(cursor.value);
            cursor.continue();  // 遍历循环存储对象中的所有内容
        } else {
            console.log("游标索引查询的结果：",list);
        }
    };
    request.onerror = function (e){};
}

// 通过索引和游标分页查询
function cursorGetDataByIndexAndPage(db,storeName,indexName,indexValue,page,pageSize) {
    let list = [];
    let counter = 0;    // 计时器
    let advanced = true;    // 是否跳过多少条数据
    var store = db.transaction(storeName,"readwrite").objectStore(storeName);   // 仓库
    var request = store
        .index(indexName)   // 索引对象
        .openCursor(IDBKeyRange.only(indexValue));  // 指针对象
    request.onsuccess = function (e) {
        var cursor = e.target.result;
        if (page>1 && advanced){
            advanced = false;
            cursor.advance((page-1) * pageSize);  // 跳过多少条
            return;
        }
        if (cursor){
            // 必须检查
            list.push(cursor.value);
            counter++;
            if (counter < pageSize){
                cursor.continue();
            } else {
                cursor = null;
                console.log("分页查询结果：",list);
            }
        } else {
            console.log("分页查询结果为：",list);
        }
    };
    request.onerror = function (e) {};
}

// 更新数据
function updateDB(db,storeName,data) {
    var request = db
        .transaction([storeName],"readwrite")
        .objectStore(storeName)
        .put(data);
    request.onerror = function () {
        console.log("更新失败")
    };
    request.onsuccess = function (){
        console.log("更新成功")
    };
}

// 通过主键删除数据
function deleteDB(db,storeName,id) {
    var request = db
        .transaction([storeName],"readwrite")
        .objectStore(storeName)
        .delete(id);
    request.onsuccess = function () {
        console.log("删除成功")
    };
    request.onerror = function () {
        console.log("删除失败")
    };
}

// 通过索引和游标删除数据
function cursorDelete(db, storeName, indexName, indexValue) {
    var store = db.transaction([storeName],"readwrite").objectStore(storeName);
    var request = store.index(indexName).openCursor(IDBKeyRange.only(indexValue));
    request.onsuccess = function (e) {
        var cursor = e.target.result;
        var deleteRequest;
        if(cursor){
            deleteRequest = cursor.delete();
            deleteRequest.onerror = function (){
                console.log("游标删除失败");
            };
            deleteRequest.onsuccess = function (){
                console.log("游标删除成功")
            };
            cursor.continue();
        }
    };
}

// 关闭数据库
function closeDB(db) {
    db.close;
    console.log("数据库关闭")
}

// 删除数据库
function deleteDBAll(dbName) {
    console.log(dbName);
    var request = window.indexedDB.deleteDatabase(dbName);
    request.onsuccess = function (event){
        console.log("删除成功")

    };
    request.onerror = function (event){
        console.log("删除失败")

    };
}