HarmonyOS NEXT 中级开发笔记：体育赛车应用中的鸿蒙数据库实践

// 使用@ohos.data.relationalStore构建数据库  import relationalStore from '@ohos.data.relationalStore';  
const SQL_CREATE_TABLE = `  CREATE TABLE IF NOT EXISTS user_profile (      uid INTEGER PRIMARY KEY AUTOINCREMENT,      name TEXT NOT NULL,      level INTEGER DEFAULT 1  );  CREATE TABLE IF NOT EXISTS car_config (      car_id INTEGER PRIMARY KEY,      engine_level INTEGER CHECK(engine_level BETWEEN 1 AND 5),      tire_type TEXT DEFAULT 'standard'  );`  
let db: relationalStore.RdbStore;  relationalStore.getRdbStore(this.context, {      name: "race_db.db",      securityLevel: relationalStore.SecurityLevel.S1  }, (err, store) => {      db = store;      db.executeSql(SQL_CREATE_TABLE);  });  

async function saveRaceResult(trackId: string, lapTime: number) {      await db.beginTransaction();      try {          const valueBucket = {              'track_id': trackId,              'lap_time': lapTime,              'record_date': new Date().toISOString()          };          await db.insert('race_records', valueBucket);          await db.commit();      } catch (e) {          await db.rollback();          console.error(`Transaction failed: ${e}`);      }  }  

let predicates = new relationalStore.RdbPredicates('race_records');  predicates.orderByDesc('lap_time')            .limit(10)            .equalTo('track_id', 'nurburgring');  
db.query(predicates, ['track_id', 'lap_time'], (err, resultSet) => {      if (resultSet.rowCount > 0) {          resultSet.goToFirstRow();          do {              console.log(`Record: ${resultSet.getString(1)} - ${resultSet.getDouble(2)}s`);          } while(resultSet.goToNextRow());      }      resultSet.close();  });