Expo SQLite（旧版）

提供对数据库的访问的库，可通过类似 WebSQL 的 API 进行查询。

expo-sqlite 使你的应用能够访问可通过类似 WebSQL 的 API 进行查询的数据库。数据库在应用重新启动后保留。

¥expo-sqlite gives your app access to a database that can be queried through a WebSQL-like API. The database is persisted across restarts of your app.

安装

¥Installation

If you are installing this in an existing React Native app (bare workflow), start by installing expo in your project. Then, follow the additional instructions as mentioned by library's README under "Installation in bare React Native projects" section.

用法

¥Usage

导入现有数据库

¥Importing an existing database

要使用现有的 .db 文件打开新的 SQLite 数据库，请按照以下步骤操作：

¥To open a new SQLite database using an existing .db file you already have, follow the steps below:

const { getDefaultConfig } = require('expo/metro-config');

const defaultConfig = getDefaultConfig(__dirname);

defaultConfig.resolver.assetExts.push('db');

module.exports = defaultConfig;

import * as FileSystem from 'expo-file-system';
import * as SQLite from 'expo-sqlite/legacy';
import { Asset } from 'expo-asset';

async function openDatabase(pathToDatabaseFile: string): Promise<SQLite.SQLiteDatabase> {
  if (!(await FileSystem.getInfoAsync(FileSystem.documentDirectory + 'SQLite')).exists) {
    await FileSystem.makeDirectoryAsync(FileSystem.documentDirectory + 'SQLite');
  }
  const asset = await Asset.fromModule(require(pathToDatabaseFile)).downloadAsync();
  await FileSystem.copyAsync({
    from: asset.localUri,
    to: FileSystem.documentDirectory + 'SQLite/myDatabaseName.db',
  });
  return SQLite.openDatabase('myDatabaseName.db');
}

使用异步事务执行语句

¥Executing statements with an async transaction

import * as SQLite from 'expo-sqlite/legacy';

const db = SQLite.openDatabase('dbName', version);

const readOnly = true;
await db.transactionAsync(async tx => {
  const result = await tx.executeSqlAsync('SELECT COUNT(*) FROM USERS', []);
  console.log('Count:', result.rows[0]['COUNT(*)']);
}, readOnly);

在事务之外执行语句

¥Executing statements outside of a transaction

仅当必要时才应该使用这种执行方式。例如，当代码在事务中是无操作时。示例：PRAGMA foreign_keys = ON;。

¥You should use this kind of execution only when it is necessary. For instance, when code is a no-op within transactions. Example: PRAGMA foreign_keys = ON;.

import * as SQLite from 'expo-sqlite/legacy';

const db = SQLite.openDatabase('dbName', version);

await db.execAsync([{ sql: 'PRAGMA foreign_keys = ON;', args: [] }], false);
console.log('Foreign keys turned on');

API

import * as SQLite from 'expo-sqlite/legacy';

Classes

Methods

Interfaces

Types