HarmonyOS NEXT 使用 relationalStore 实现数据库操作

import relationalStore from '@ohos.data.relationalStore';import promptAction from '@ohos.promptAction';
@Entry@Componentstruct RdbStoreExample {  @State userList: Array<{ id: number; name: string; age: number }> = [];  @State nameInput: string = '';  @State ageInput: string = '';  private rdbStore: relationalStore.RdbStore | null = null;  private rdbConfig: relationalStore.RdbStoreConfig = {    name: 'UserData.db',    securityLevel: relationalStore.SecurityLevel.S1  };  private CREATE_TABLE_USER =     'CREATE TABLE IF NOT EXISTS User (' +    'id INTEGER PRIMARY KEY AUTOINCREMENT, ' +    'name TEXT NOT NULL, ' +    'age INTEGER NOT NULL)';
  aboutToAppear() {    this.openRdbStore();  }
  aboutToDisappear() {    this.closeRdbStore();  }
  // 打开数据库  async openRdbStore() {    try {      this.rdbStore = await relationalStore.getRdbStore(this.rdbConfig, 1,         (version: number, rdbStore: relationalStore.RdbStore) => {          if (version === 1) {            rdbStore.executeSql(this.CREATE_TABLE_USER, []);          }        });      await this.queryUsers();    } catch (error) {      console.error(`Failed to open RDB store: ${error}`);      promptAction.showToast({ message: '数据库打开失败' });    }  }
  // 关闭数据库  async closeRdbStore() {    if (this.rdbStore) {      try {        await this.rdbStore.close();        this.rdbStore = null;      } catch (error) {        console.error(`Failed to close RDB store: ${error}`);      }    }  }
  // 插入数据  async insertUser() {    if (!this.nameInput || !this.ageInput) {      promptAction.showToast({ message: '请输入姓名和年龄' });      return;    }        try {      const valuesBucket = {        name: this.nameInput,        age: parseInt(this.ageInput)      };            const id = await this.rdbStore?.insert('User', valuesBucket);      if (id && id > 0) {        promptAction.showToast({ message: '插入成功' });        await this.queryUsers();        this.nameInput = '';        this.ageInput = '';      }    } catch (error) {      console.error(`Failed to insert data: ${error}`);      promptAction.showToast({ message: '插入失败' });    }  }
  // 查询数据  async queryUsers() {    try {      const resultSet = await this.rdbStore?.querySql(        'SELECT * FROM User', []);            if (resultSet) {        const users = [];        resultSet.goToFirstRow();                while (!resultSet.isAtEnd()) {          users.push({            id: resultSet.getLong(resultSet.getColumnIndex('id')),            name: resultSet.getString(resultSet.getColumnIndex('name')),            age: resultSet.getInt(resultSet.getColumnIndex('age'))          });          resultSet.goToNextRow();        }                this.userList = users;        resultSet.close();      }    } catch (error) {      console.error(`Failed to query data: ${error}`);      promptAction.showToast({ message: '查询失败' });    }  }
  // 更新数据  async updateUser(id: number, name: string, age: number) {    try {      const valuesBucket = {        name: name,        age: age      };            const conditions = new relationalStore.RdbStorePredicates('User');      conditions.equalTo('id', id.toString());            const rowsAffected = await this.rdbStore?.update(        valuesBucket, conditions);            if (rowsAffected && rowsAffected > 0) {        promptAction.showToast({ message: '更新成功' });        await this.queryUsers();      }    } catch (error) {      console.error(`Failed to update data: ${error}`);      promptAction.showToast({ message: '更新失败' });    }  }
  // 删除数据  async deleteUser(id: number) {    try {      const conditions = new relationalStore.RdbStorePredicates('User');      conditions.equalTo('id', id.toString());            const rowsAffected = await this.rdbStore?.delete(conditions);            if (rowsAffected && rowsAffected > 0) {        promptAction.showToast({ message: '删除成功' });        await this.queryUsers();      }    } catch (error) {      console.error(`Failed to delete data: ${error}`);      promptAction.showToast({ message: '删除失败' });    }  }
  build() {    Column() {      // 输入表单      Column() {        Input({          placeholder: '请输入姓名',          type: InputType.Text        })        .width('100%')        .margin({ top: 10, bottom: 10 })        .onChange((value: string) => {          this.nameInput = value;        })                Input({          placeholder: '请输入年龄',          type: InputType.Number        })        .width('100%')        .margin({ top: 10, bottom: 10 })        .onChange((value: string) => {          this.ageInput = value;        })                Button('添加用户')        .width('100%')        .onClick(() => {          this.insertUser();        })      }      .width('90%')      .margin({ top: 20, bottom: 20 })            // 用户列表      List() {        ForEach(this.userList, (user) => {          ListItem() {            Row() {              Column() {                Text(`姓名: ${user.name}`)                Text(`年龄: ${user.age}`)              }              .width('70%')                            Column() {                Button('修改')                .onClick(() => {                  const newName = promptAction.showPromptDialog({                    message: '请输入新姓名',                    defaultValue: user.name                  });                  const newAge = promptAction.showPromptDialog({                    message: '请输入新年龄',                    defaultValue: user.age.toString()                  });                  if (newName && newAge) {                    this.updateUser(user.id, newName, parseInt(newAge));                  }                })                                Button('删除')                .onClick(() => {                  this.deleteUser(user.id);                })              }              .width('30%')            }            .width('100%')          }        })      }      .width('90%')      .margin({ top: 10, bottom: 10 })    }    .width('100%')    .height('100%')    .padding(15)  }}