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| package com.example.sqltest;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class MyDataBaseAdapter {
// 用于打印log
private static final String TAG = "MyDataBaseAdapter";
// 表中一条数据的名称
public static final String KEY_ID = "_id";
// 表中一条数据的内容
public static final String KEY_NUM = "num";
// 表中一条数据的id
public static final String KEY_DATA = "data";
// 数据库名称为data
private static final String DB_NAME = "Examples1.db";
// 数据库表名
private static final String DB_TABLE = "table1";
// 数据库版本
private static final int DB_VERSION = 1;
// 本地Context对象
private Context mContext = null;
// 创建一个表
private static final String DB_CREATE = "CREATE TABLE " + DB_TABLE + " ("
+ KEY_ID + " INTEGER PRIMARY KEY," + KEY_NUM + " INTERGER,"
+ KEY_DATA + " TEXT)";
// 执行open（）打开数据库时，保存返回的数据库对象
private SQLiteDatabase mSQLiteDatabase = null;
// 由SQLiteOpenHelper继承过来
private DatabaseHelper mDatabaseHelper = null;
private static class DatabaseHelper extends SQLiteOpenHelper {
/* 构造函数-创建一个数据库 */
DatabaseHelper(Context context) {
// 当调用getWritableDatabase()
// 或 getReadableDatabase()方法时
// 则创建一个数据库
super(context, DB_NAME, null, DB_VERSION);
}
/* 创建一个表 */
@Override
public void onCreate(SQLiteDatabase db) {
// 数据库没有表时创建一个
db.execSQL(DB_CREATE);
}
/* 升级数据库 */
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS notes");
onCreate(db);
}
}
/* 构造函数-取得Context */
public MyDataBaseAdapter(Context context) {
mContext = context;
}
// 打开数据库，返回数据库对象
public void open() throws SQLException {
mDatabaseHelper = new DatabaseHelper(mContext);
mSQLiteDatabase = mDatabaseHelper.getWritableDatabase();
}
// 关闭数据库
public void close() {
mDatabaseHelper.close();
}
/* 插入一条数据 */
public long insertData(int num, String data) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_NUM, num);
initialValues.put(KEY_DATA, data);
return mSQLiteDatabase.insert(DB_TABLE, KEY_ID, initialValues);
}
/* 删除一条数据 */
public boolean deleteData(long rowId) {
return mSQLiteDatabase.delete(DB_TABLE, KEY_ID + "=" + rowId, null) > 0;
}
/* 通过Cursor查询所有数据 */
public Cursor fetchAllData() {
return mSQLiteDatabase.query(DB_TABLE, new String[] { KEY_ID, KEY_NUM,
KEY_DATA }, null, null, null, null, null);
}
/* 查询指定数据 */
public Cursor fetchData(long rowId) throws SQLException {
Cursor mCursor = mSQLiteDatabase.query(true, DB_TABLE, new String[] {
KEY_ID, KEY_NUM, KEY_DATA }, KEY_ID + "=" + rowId, null, null,
null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
/* 更新一条数据 */
public boolean updateData(long rowId, int num, String data) {
ContentValues args = new ContentValues();
args.put(KEY_NUM, num);
args.put(KEY_DATA, data);
return mSQLiteDatabase.update(DB_TABLE, args, KEY_ID + "=" + rowId,
null) > 0;
}
}
|