Android实现对SQLite数据库增删改查
时间: 2024-01-06 21:04:49 浏览: 36
好的,我可以帮你解答这个问题。在 Android 中实现对 SQLite 数据库的增删改查,需要通过 SQLiteOpenHelper 类来创建和管理数据库。下面是一个示例:
1. 创建 SQLiteOpenHelper 类
```java
public class DBHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "mydatabase.db";
private static final int DATABASE_VERSION = 1;
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql = "CREATE TABLE mytable (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER)";
db.execSQL(sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
String sql = "DROP TABLE IF EXISTS mytable";
db.execSQL(sql);
onCreate(db);
}
}
```
2. 增加数据
```java
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("name", "张三");
values.put("age", 18);
long id = db.insert("mytable", null, values);
```
3. 删除数据
```java
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getWritableDatabase();
String whereClause = "name=?";
String[] whereArgs = new String[]{"张三"};
int count = db.delete("mytable", whereClause, whereArgs);
```
4. 修改数据
```java
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("age", 20);
String whereClause = "name=?";
String[] whereArgs = new String[]{"张三"};
int count = db.update("mytable", values, whereClause, whereArgs);
```
5. 查询数据
```java
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getReadableDatabase();
String[] columns = new String[]{"name", "age"};
String selection = "name=?";
String[] selectionArgs = new String[]{"张三"};
String groupBy = null;
String having = null;
String orderBy = null;
String limit = null;
Cursor cursor = db.query("mytable", columns, selection, selectionArgs, groupBy, having, orderBy, limit);
while (cursor.moveToNext()) {
String name = cursor.getString(cursor.getColumnIndex("name"));
int age = cursor.getInt(cursor.getColumnIndex("age"));
}
```
以上就是 Android 实现对 SQLite 数据库增删改查的示例代码,你可以根据自己的需求进行修改。