Android：数据库增删改查、SQLite、ORM、Cursor

1.继承类SQLiteOpenHelper：

public class MySQLiteHelper extends SQLiteOpenHelper
{
    //重写构造方法
    public MySQLiteHelper(Context context, String name, CursorFactory factory,
            int version)
    {
        super(context, name, factory, version);
    }
    //创建表
    @Override
    public void onCreate(SQLiteDatabase db)
    {
        db.execSQL("CREATE TABLE person(personid INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR(20),phone VARCHAR(20))" );
        db.execSQL("CREATE TABLE student(personid INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR(20),phone VARCHAR(20))" );
    }
    //升级表（当Database的Version低于当前new里的Version，直接执行下面方法）
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
    {
                                   
        int v = newVersion - oldVersion;
        switch (v)
        {
        case 3:
            db.execSQL("ALTER TABLE person ADD salary3 VARCHAR(20)");
        case 2:
            db.execSQL("ALTER TABLE person ADD salary2 VARCHAR(20)");
        case 1:
            db.execSQL("ALTER TABLE person ADD salary1 VARCHAR(20)");
        default:
            break;
        }
    }
}

2.实现增删改查：

/**
 *
CREATE TABLE person
(
       personid INTEGER PRIMARY KEY AUTOINCREMENT,
       name VARCHAR(20),
       phone VARCHAR(20)
)
DROP TABLE person  //删除表
INSERT INTO person(name,phone) VALUES ("rongqin","1598088588")  //插入
UPDATE person SET name="Andfeel" WHERE personid=2   //改
ALTER TABLE person ADD salary      //增加列
DELETE FROM person WHERE name="Andfeel"    //删除
                    
SELECT * FROM person WHERE name="Andfeel"
SELECT phone,name FROM person
SELECT name,phone FROM person ORDER BY name ASC"//ASC升序     DESC降序 
                    
 *
 */
public class MainActivity extends Activity implements OnClickListener
{
                      
    private TextView textView;
    private MySQLiteHelper mDBHelper;
    private MySQLiteHelper bHelper;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
                          
        findViewById(R.id.btn__create_table).setOnClickListener(this);
        findViewById(R.id.btn_delete_table).setOnClickListener(this);
        findViewById(R.id.btn_alter_table).setOnClickListener(this);
        findViewById(R.id.btn_insert).setOnClickListener(this);
        findViewById(R.id.btn_delete).setOnClickListener(this);
        findViewById(R.id.btn_update).setOnClickListener(this);
        findViewById(R.id.btn_select).setOnClickListener(this);
        textView = (TextView) findViewById(R.id.textView1);
                          
        //创建数据库
        mDBHelper = new MySQLiteHelper(this, "one.db", null, 3);
    }
                      
    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
    @Override
    public void onClick(View v)
    {
        switch (v.getId())
        {
        case R.id.btn__create_table:
            btnCreateTable();
            break;
        case R.id.btn_delete_table:
            btnDeleteTable();
            break;
        case R.id.btn_alter_table:
            btnAlterTable();
            break;
        case R.id.btn_insert:
            btnInsert();
            break;
        case R.id.btn_delete:
            btnDelete();
            break;
        case R.id.btn_update:
            btnUpdate();
            break;
        case R.id.btn_select:
            btnSelect();
            break;
                          
        default:
            break;
        }
    }
    private void btnSelect()//查
    {
        SQLiteDatabase db = mDBHelper.getWritableDatabase();
                          
//        Cursor cursor = db.rawQuery("SELECT * FROM person WHERE name = ?", new String[]{"rongqin"});
//        cursor.moveToFirst();
                          
        Cursor cursor = db.query(
                "person",                       //表名
                new String[]{"phone","name"},   //查询的列名
                "name=?",                     //查询条件
                new String[]{"huangxx"},        //查询参数
                null, null,
                "phone DESC");                  //排序，升序为ASC，降序为DESC
        boolean hasdata = cursor.moveToFirst();//游标移到第一行
                          
        StringBuilder sb = new StringBuilder();
        while(hasdata)//是否有数据
        {
            int columnIndex = cursor.getColumnIndex("name");//得到name的列数
            String name = cursor.getString(columnIndex);//得到name这一列的值
                              
            int columnIndex2 = cursor.getColumnIndex("phone");
            String phone = cursor.getString(columnIndex2);
                              
            sb.append("name:").append(name).append(" phone:").append(phone).append("--");
            hasdata = cursor.moveToNext();//游标移动到下一行，判断是否有值
        }
        textView.setText(sb.toString());
    }
    private void btnUpdate()//改
    {
        SQLiteDatabase db = mDBHelper.getWritableDatabase();
//        db.execSQL("UPDATE person SET phone='0592xxxxxx' WHERE personid=5");
                          
        ContentValues values = new ContentValues();
        values.put("name", "haoyouduo");
        values.put("phone", "666666");
        db.update("person", values , "personid=?" , new String[]{"8"});
    }
    private void btnDelete()//删
    {
        SQLiteDatabase db = mDBHelper.getWritableDatabase();
//        db.execSQL("DELETE FROM person WHERE name='Andfeel'");
                          
        db.delete("person","name = ? and personid = ?", new String[]{"haoyouduo" , "5"});
    }
    private void btnInsert()//增
    {
        SQLiteDatabase db = mDBHelper.getWritableDatabase();
//        db.execSQL("INSERT INTO person(name,phone) VALUES ('rongqin',1598088588)");
                          
        ContentValues values = new ContentValues();
        values.put("name", "huangxx");
        values.put("phone", "158888");
        db.insert("person", null , values );
    }
    private void btnAlterTable()//扩展表
    {
                          
    }
    private void btnDeleteTable()//删除表
    {
                          
    }
    private void btnCreateTable()//创建表
    {
                          
    }
}

其他总结:

1.关闭数据源

/**
 * 关闭数据源
 */
public void closeConnection()
{
    if (mDb != null && mDb.isOpen())
        mDb.close();
    if (mDbHelper != null)
        mDbHelper.close();
}

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