HarmonyOS Next 入门实战 - 关系型数据库、smartdb

SQLite数据库

HarmonyOS的关系型数据库基于SQLite
导入模块

import { relationalStore } from '@kit.ArkData';

实现步骤：

1. 获取RdbStore对象，用于创建数据库，数据表，以及数据库升级等操作

let storeConfig = {name: 'Poetry.db',  //数据库文件名securityLevel: relationalStore.SecurityLevel.S1,  //安全级别encrypt: false, //是否加密，可选，默认不加密customDir: '', 	//自定义路径，可选，目录：context.databaseDir + '/rdb/' + customDirisReadOnly: false, //是否已只读方式打开，可选，默认false
}relationalStore.getRdbStore(this.context, this.storeConfig).then(store => {//创建表store.executeSql('sql')//判断版本store.version}).catch((err: Error) => {})

2. 插入数据

let data :ValuesBucket={name:"zhangsan",age: 23,
}
store.insert("tableName",data).then((rowId)=>{//操作成功返回rowId,否则返回-1
})store.batchInsert() //用于插入批量数据

3. 修改，删除数据：通过组件提供的谓词(Predicates)修改或删除组件

let data :ValuesBucket={name:"zhangsan",age: 26,
}
let predicates = new relationalStore.RdbPredicates("tableName")
predicates.equalTo("name","zhangsan")
//更新数据
store.update(data,predicates).then((value)=>{})//删除数据
store.delete(predicates).then((value)=>{})

4. 查询数据

let predicates = new relationalStore.RdbPredicates("tableName")
predicates.equalTo("name","zhangsan")
store.query(predicates).then((resultSet)=>{while (resultSet.goToNextRow()){const name = resultSet.getString(resultSet.getColumnIndex("name"))const age = resultSet.getLong(resultSet.getColumnIndex("age"))}resultSet.close()
})
//也可以通过下面接口使用sql查询
store.querySql(sql: string, bindArgs?: Array<ValueType>): Promise<ResultSet>;

5. 备份数据和恢复数据

//备份数据
store.backup("backup.db")
//恢复数据
store.restore("backup.db")

SmartDB

SmartDB与Android中的room组件类似，可以简化我们数据库操作的步骤，使代码更易维护。
安装和导入模块

//安装模块
ohpm install @liushengyi/smartdb
//导入模块
import sql from "@liushengyi/smartdb"

定义数据结构：

export class Poetry {@sql.SqlColumn(sql.ColumnType.TEXT)uuid?: string@sql.SqlColumn(sql.ColumnType.TEXT)title?: string@sql.SqlColumn(sql.ColumnType.TEXT)dynasty?: string@sql.SqlColumn(sql.ColumnType.TEXT)author?: string@sql.SqlColumn(sql.ColumnType.TEXT)introduction?: string@sql.SqlColumn(sql.ColumnType.TEXT)text?: string@sql.SqlColumn(sql.ColumnType.TEXT)textAlign?: string@sql.SqlColumn(sql.ColumnType.TEXT)translation?: string@sql.SqlColumn(sql.ColumnType.TEXT)rectify?: string@sql.SqlColumn(sql.ColumnType.TEXT)searchKey?: string
}

执行数据库操作：进行增删改查、事务操作

export class PoetryDao {public static TABLE_NAME = "Poetry"public static SQL_CREATE_TABLE ="CREATE TABLE IF NOT EXISTS `Poetry` (`uuid` TEXT NOT NULL, `title` TEXT, `dynasty` TEXT, `author` TEXT, `introduction` TEXT, `text` TEXT, `textAlign` TEXT, `translation` TEXT, `rectify` TEXT, `searchKey` TEXT, PRIMARY KEY(`uuid`))"@sql.SqlQuery(`select * from ${PoetryDao.TABLE_NAME} where uuid=#{uuid}`)@sql.ReturnType(Poetry)queryOne(@sql.Param('uuid') uuid: string): Promise<Poetry> {return sql.PromiseNull()}@sql.SqlQuery(`select count(*) from ${PoetryDao.TABLE_NAME} `)@sql.ReturnType(Number)queryCount(): Promise<Number> {return sql.PromiseNull()}@sql.SqlInsert(`insert into ${PoetryDao.TABLE_NAME} values (#{data.uuid},#{data.title},#{data.dynasty},#{data.author},#{data.introduction},#{data.text},#{data.textAlign},#{data.translation},#{data.rectify},#{data.searchKey})`)insert(@sql.Param('data') data: Poetry): Promise<void> {return sql.PromiseNull()}@sql.Transactional()async insertPoetryAll(list: Poetry[]) {for (let item of list) {await this.insert(item)}}
}

数据库管理：创建数据库、数据库升级

export class DatabaseManager {static readonly DATABASE_VERSION = 1static readonly DATABASE_NAME = 'poetry.db'static init(context: Context) {sql.dbHelper.initDb(context,DatabaseManager.DATABASE_NAME,DatabaseManager.DATABASE_VERSION,new DbOpenHelperImpl())}
}class DbOpenHelperImpl extends sql.DbOpenHelper {//创建数据库onCreate(db: relationalStore.RdbStore): void {db.executeSql(PoetryDao.SQL_CREATE_TABLE)}//升级数据onUpgrade(db: relationalStore.RdbStore, oldVersion: number, newVersion: number): void {}
}

最后在app启动的时候调用初始化方法

export default class EntryAbility extends UIAbility {onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {hilog.info(0x0000, 'testTag', '%{public}s', 'Ability onCreate');DatabaseManager.init(this.context)}
}

数据初始化和使用

将json格式的数据插入到数据库中

poetryDao: PoetryDao = new PoetryDao()new Promise<boolean>(async (resolve, reject) => {try {let count = await this.poetryDao.queryCount()if (!count) {let list = await (await import("resources/rawfile/poetry.json")).defaultlet poetryArray: Array<Poetry> = []for (let item of list) {let poetry = item as Poetrypoetry.uuid = util.generateRandomUUID()if (poetry.rectify) {poetry.rectify = JSON.stringify(poetry.rectify)}poetryArray.push(poetry)}this.poetryDao.insertPoetryAll(poetryArray)resolve(true)} else {resolve(false)}} catch (e) {reject(e)}
})

读取数据

//读取所有数据
new PoetryDao().queryList().then((value) => {})
//读取一条数据
new PoetryDao().queryOne("id").then((value) => {})

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本文的技术设计和实现都是基于作者工作中的经验总结，如有错误，请留言指正，谢谢。