安卓数据库增删改查源码
时间: 2023-09-01 17:10:44 浏览: 63
好的,以下是一个使用 SQLite 数据库进行增删改查的 Android 源代码示例:
1. 创建数据库帮助类 DBHelper.java
```
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "my_database.db";
private static final int DATABASE_VERSION = 1;
private static final String TABLE_NAME = "my_table";
private static final String COLUMN_ID = "_id";
private static final String COLUMN_NAME = "name";
private static final String COLUMN_AGE = "age";
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String query = "CREATE TABLE " + TABLE_NAME + " (" +
COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
COLUMN_NAME + " TEXT, " +
COLUMN_AGE + " INTEGER);";
db.execSQL(query);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
String query = "DROP TABLE IF EXISTS " + TABLE_NAME;
db.execSQL(query);
onCreate(db);
}
}
```
2. 在 Activity 中使用 DBHelper 进行增删改查操作 MainActivity.java
```
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
private DBHelper dbHelper;
private SQLiteDatabase db;
private TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = findViewById(R.id.textView);
dbHelper = new DBHelper(this);
db = dbHelper.getWritableDatabase();
// 插入数据
ContentValues values = new ContentValues();
values.put(DBHelper.COLUMN_NAME, "Tom");
values.put(DBHelper.COLUMN_AGE, 18);
db.insert(DBHelper.TABLE_NAME, null, values);
// 更新数据
values.put(DBHelper.COLUMN_AGE, 20);
db.update(DBHelper.TABLE_NAME, values, DBHelper.COLUMN_NAME + "=?", new String[]{"Tom"});
// 查询数据
Cursor cursor = db.query(DBHelper.TABLE_NAME, null, null, null, null, null, null);
if (cursor != null) {
StringBuilder sb = new StringBuilder();
while (cursor.moveToNext()) {
int id = cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_ID));
String name = cursor.getString(cursor.getColumnIndex(DBHelper.COLUMN_NAME));
int age = cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_AGE));
sb.append("id: ").append(id).append(", name: ").append(name).append(", age: ").append(age).append("\n");
}
textView.setText(sb.toString());
cursor.close();
}
// 删除数据
db.delete(DBHelper.TABLE_NAME, DBHelper.COLUMN_NAME + "=?", new String[]{"Tom"});
dbHelper.close();
}
}
```
以上代码演示了如何使用 SQLite 数据库进行增删改查操作,具体包括:
- 创建数据库帮助类 DBHelper.java
- 在 Activity 中使用 DBHelper 进行数据库操作,包括插入数据、更新数据、查询数据和删除数据
注意:上述代码仅为示例,实际开发中需要根据具体需求进行修改和完善。
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