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);
		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,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,whereValue);
	}
}

（编辑：李大同）

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