场景：
在移动应用开发中，确保应用在无网络连接时仍能正常运行并进行数据同步至关重要。
对于uni-app开发者而言，SQLite是理想的本地存储解决方案，支持结构化数据的存储和检索。本文将介绍如何在uni-app项目中使用SQLite实现离线数据同步，包括封装sqlite.js简化数据库操作、测试数据库连接，需要在真机或雷电模拟器上进行调试。不能用内嵌的web浏览器，因为封装的sqlite里面的plus是只识别安卓；
注意：为实现离线数据同步，不能依赖终端部署的JAR包，而是直接使用SQLite进行数据处理。
1、在你的uni-app项目中创建一个名为sqlite.js的文件，包含所有与SQLite数据库交互的方法
module.exports = {dbName: '444', // 数据库名称dbPath: '/storage/emulated/0/Pictures/444.db', // 数据库地址,推荐以下划线为开头 _doc/xxx.db /*** @Description: 创建数据库 或 有该数据库就打开* * * */openSqlite() {return new Promise((resolve, reject) => {// 打开数据库plus.sqlite.openDatabase({name: this.dbName,path: this.dbPath,success(e) {resolve(e); },fail(e) {reject(e); }})})},/*** @Description: 判断数据库是否打开 数据库打开了就返回 true,否则返回 false* * @createTime: * */isOpen() {var open = plus.sqlite.isOpenDatabase({name: this.dbName, // 数据库名称path: this.dbPath // 数据库地址})return open;},/*** @Description: 创建表（executeSql是执行增删改等操作的SQL语句）* * @createTime: * */ExecuteSQL(sql) {return new Promise((resolve, reject) => {plus.sqlite.executeSql({name: this.dbName,sql: sql,success(e) {resolve(e);},fail(e) {reject(e);}})})},/*** @Description: 查询表数据* * @createTime: 2023-10-12 08:52:15* */getTable(dbTable){return new Promise((resolve, reject) => {plus.sqlite.selectSql({name: this.dbName,sql: `SELECT * FROM ${dbTable}`,success(e) {resolve(e);},fail(e) {console.log(e)reject(e);}})})},/*** @Description: 查询表数据* * @createTime: 2023-10-12 08:52:15* */getSelectData(sql){return new Promise((resolve, reject) => {plus.sqlite.selectSql({name: this.dbName,sql: sql,success(e) {resolve(e);},fail(e) {console.log(e)reject(e);}})})},/*** @Description: 查询数据库所有表* * @createTime: 2023-10-12 09:01:05* */QueryAllTables(){return new Promise((resolve, reject) => {plus.sqlite.selectSql({name: this.dbName,sql: "SELECT * FROM sqlite_master WHERE type='table'",success(e) {resolve(e);},fail(e) {console.log(e)reject(e);}})})},/*** @Description: 查询数据库下的所有表* * @createTime: 2023-10-12 09:20:33* */selectTableName(){return new Promise((resolve, reject) => {plus.sqlite.selectSql({name: this.dbName,sql: "select * FROM chat where type='table'",success(e) {resolve(e);},fail(e) {console.log(e)reject(e);}})})},/*** @Description: 新增数据* * 向表格里添加数据 sql:'INSERT INTO dbTable VALUES('x','x','x')' 对应新增* 或者 sql:'INSERT INTO dbTable ('x','x','x') VALUES('x','x','x')' 具体新增* 插入 INSERT INTO 、 dbTable 是表名、根据表头列名插入列值* @createTime: 2023-10-12 10:21:32* *///使用// let arr = [// {id:121,dept_id: '100',dept_name: '你好呀'},// {id:332,dept_id: '200',dept_name: '你好呀'},// ]// arr.map((item) => {// let condition = "'id','dept_id','dept_name'"// let data = `'${item.id}','${item.dept_id}','${item.dept_name}'`// DB.insertTableData('表名',数据,字段).then((res) => {})// .catch((error) => {// console.log('失败', error)// })// })insertTableData(dbTable, data, condition) {// 判断有没有传参if (dbTable !== undefined && data !== undefined) {// 判断传的参是否有值var bol = (JSON.stringify(data) == "{}");if (!bol) {if (condition == undefined) var sql = `INSERT INTO ${dbTable} VALUES('${data}')`;else var sql = `INSERT INTO ${dbTable} (${condition}) VALUES(${data})`;return new Promise((resolve, reject) => {// 表格添加数据plus.sqlite.executeSql({name: this.dbName,sql: sql,success(e) {resolve(e);},fail(e) {reject(e);}})})} else {return new Promise((resolve, reject) => { reject("错误添加") })}} else {return new Promise((resolve, reject) => { reject("错误添加") })}},/*** @Description: 数据库建表* * 数据库建表 sql:'CREATE TABLE IF NOT EXISTS dbTable("id" varchar(50),"name" TEXT) * 创建 CREATE TABLE IF NOT EXISTS 、 dbTable 是表名，不能用数字开头、括号里是表格的表头* @createTime: 2023-10-12 09:26:44* */// 使用// DB.createTable('bus_mzpy','"id" INTEGER PRIMARY KEY AUTOINCREMENT,"mzpy_name" TEXT ,"dept_id" INTEGER ,"dept_name" TEXT ,"mzpy_concent" TEXT')createTable(dbTable, data) { return new Promise((resolve, reject) => {// executeSql: 执行增删改等操作的SQL语句plus.sqlite.executeSql({name: this.dbName,sql: `CREATE TABLE IF NOT EXISTS ${dbTable}(${data})`,success(e) {resolve(e);},fail(e) {reject(e);}})})},/*** @Description: 数据库删表 sql:'DROP TABLE dbTable'* * @createTime: 2023-10-12 09:28:46* */dropTable(dbTable) {return new Promise((resolve, reject) => {plus.sqlite.executeSql({name: this.dbName,sql: `DROP TABLE ${dbTable}`,success(e) {resolve(e);},fail(e) {reject(e);}})})},/*** @Description: 根据条件向表里插入数据、更新或覆盖* * 根据条件向表格里添加数据 有数据更新、无数据插入* (建表时需要设置主键) 例如 --- "roomid" varchar(50) PRIMARY KEY* @createTime: 2023-10-12 09:31:19* 1,名字 ，id,name */insertOrReplaceData(dbTable, data, condition) {// 判断有没有传参if (dbTable !== undefined && data !== undefined) {if (condition == undefined) var sql = `INSERT OR REPLACE INTO ${dbTable} VALUES('${data}')`;else var sql = `INSERT OR REPLACE INTO ${dbTable} (${condition}) VALUES(${data})`;return new Promise((resolve, reject) => {// 表格添加数据plus.sqlite.executeSql({name: this.dbName,sql: sql,success(e) {resolve(e);},fail(e) {reject(e);}})})} else {return new Promise((resolve, reject) => { reject("错误添加") })}},/*** @Description: 表里查询数据* * 查询获取数据库里的数据 sql:'SELECT * FROM dbTable WHERE lname = 'lvalue''* 查询 SELECT * FROM 、 dbTable 是表名、 WHERE 查找条件 lname,lvalue 是查询条件的列名和列值* @createTime: 2023-10-12 09:44:08* */ selectTableData(dbTable, lname, lvalue, cc, dd) {if (dbTable !== undefined) {let sql;// 第一个是表单名称，后两个参数是列表名，用来检索// 两个检索条件if (lname !== undefined && cc !== undefined) sql=`SELECT * FROM ${dbTable} WHERE ${lname} = '${lvalue}' AND ${cc} = '${dd}'`;// 一个检索条件if (lname !== undefined && cc == undefined) sql = `SELECT * FROM ${dbTable} WHERE ${lname} = '${lvalue}'`;if (lname == undefined) sql = `SELECT * FROM ${dbTable}`;return new Promise((resolve, reject) => {// 表格查询数据 执行查询的SQL语句plus.sqlite.selectSql({name: this.dbName,sql: sql,success(e) {resolve(e);},fail(e) {reject(e);}})})} else {return new Promise((resolve, reject) => { reject("错误查询") });}},/*** @Description: 表里删除数据* * 删除表里的数据 sql:'DELETE FROM dbTable WHERE lname = 'lvalue''* 删除 DELETE FROM 、 dbTable 是表名、 WHERE 查找条件 lname,lvalue 是查询条件的列名和列值* @createTime: 2023-10-12 09:40:37* */deleteTableData(dbTable, lname, lvalue, ww, ee) {if(dbTable !== undefined){let sql;if(lname == undefined){sql = `DELETE FROM ${dbTable}`;}else{if (ww !== undefined) {// 两个检索条件sql = `DELETE FROM ${dbTable} WHERE ${lname} = '${lvalue}' AND ${ww} = '${ee}'`;} else {// 一个检索条件sql = `DELETE FROM ${dbTable} WHERE ${lname} = '${lvalue}'`;}}return new Promise((resolve, reject) => {// 删除表数据plus.sqlite.executeSql({name: this.dbName,sql: sql,success(e) {resolve(e);},fail(e) {reject(e);}})})} else {return new Promise((resolve, reject) => { reject("错误删除") });}},/*** @Description: 表里修改数据* * 修改数据表里的数据 sql:"UPDATE dbTable SET 列名 = '列值',列名 = '列值' WHERE lname = 'lvalue'"* 修改 UPDATE 、 dbTable 是表名, data: 要修改的列名=修改后列值, lname,lvalue 是查询条件的列名和列值* @createTime: 2023-10-12 09:37:59* */updateTableData(dbTable, data, lname, lvalue) {let sql;if (lname == undefined) sql = `UPDATE ${dbTable} SET ${data}`;else sql = `UPDATE ${dbTable} SET ${data} WHERE ${lname} = '${lvalue}'`;// WHERE 前面是要修改的列名、列值，后面是条件的列名、列值return new Promise((resolve, reject) => {// 修改表数据plus.sqlite.executeSql({name: this.dbName,sql: sql,success(e) {resolve(e);},fail(e) {reject(e);}})})},/*** @Description: 获取指定数据条数* * 获取指定数据条数 sql:"SELECT * FROM dbTable ORDER BY 'id' DESC LIMIT 15 OFFSET 'num'"* dbTable 表名, ORDER BY 代表排序默认正序, id 是排序的条件 DESC 代表倒序，从最后一条数据开始拿* LIMIT 15 OFFSET '${num}',这句的意思是跳过 num 条拿 15 条数据, num 为跳过多少条数据是动态值* 例 初始num设为0，就从最后的数据开始拿15条，下次不拿刚获取的数据，所以可以让num为15，这样就能一步一步的拿完所有的数据* @createTime: 2023-10-12 09:33:43* */pullSQL(dbTable, id, num) {return new Promise((resolve, reject) => {plus.sqlite.selectSql({name: this.dbName,sql: `SELECT * FROM ${dbTable} ORDER BY '${id}' DESC LIMIT 15 OFFSET '${num}'`,success(e) {resolve(e);},fail(e) {reject(e);}})})},/*** @Description: 关闭数据库* * @createTime: 2023-10-12 09:23:56* */closeSqlite() {return new Promise((resolve, reject) => {plus.sqlite.closeDatabase({name: this.dbName,success(e) {resolve(e);},fail(e) {reject(e);}})})},
}2、测试数据库是否成功打开
import DB from '@/sqlite/sqlite.js' //引入//创建数据库 DB.openSqlite() // // //测试保存console.log("是否打开数据库" + DB.isOpen())// // 类似这样DB.getTable('jc_repair_historical_record').then((res) => {console.log('11111111db文件', res)}).catch((error) => {console.log('查询失败', error)})//关闭数据库DB.closeSqlite()3、在真机或雷电模拟器上测试
由于plus相关的API仅能在真机或类似安卓手机的雷电模拟器上运行，因此这是验证SQLite数据库操作的最佳环境。请确保你已准备好相应的设备或模拟器，并按照上述步骤进行测试。
最后感谢阅读，如有不足指出，请指正，谢谢。