SQLite数据库操作

Android SQLiteOpenHelper SQLite数据库增删改查操作

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class ToDoDB extends SQLiteOpenHelper {
    private final static String DATABASE_NAME = "todo_db";
    private final static int DATABASE_VERSION = 1;
    private final static String TABLE_NAME = "todo_table";
    public final static String FIELD_id = "_id";
    public final static String FIELD_TEXT = "todo_text";

    public ToDoDB(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        /* 建立table */
        String sql = "CREATE TABLE " + TABLE_NAME + " (" + FIELD_id
                + " INTEGER primary key autoincrement, " + " " + FIELD_TEXT
                + " text)";
        db.execSQL(sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        String sql = "DROP TABLE IF EXISTS " + TABLE_NAME;
        db.execSQL(sql);
        onCreate(db);
    }

    public Cursor select() {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db
                .query(TABLE_NAME, null, null, null, null, null, null);
        return cursor;
    }

    public long insert(String text) {
        SQLiteDatabase db = this.getWritableDatabase();
        /* 将新增的值放入ContentValues */
        ContentValues cv = new ContentValues();
        cv.put(FIELD_TEXT, text);
        long row = db.insert(TABLE_NAME, null, cv);
        return row;
    }

    public void delete(int id) {
        SQLiteDatabase db = this.getWritableDatabase();
        String where = FIELD_id + " = ?";
        String[] whereValue = { Integer.toString(id) };
        db.delete(TABLE_NAME, where, whereValue);
    }

    public void update(int id, String text) {
        SQLiteDatabase db = this.getWritableDatabase();
        String where = FIELD_id + " = ?";
        String[] whereValue = { Integer.toString(id) };
        /* 将修改的值放入ContentValues */
        ContentValues cv = new ContentValues();
        cv.put(FIELD_TEXT, text);
        db.update(TABLE_NAME, cv, where, whereValue);
    }
}