Sqlite数据库

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//数据库类

public class StudentDatabase extends SQLiteOpenHelper {

    public StudentDatabase(@Nullable Context context) {
        super(context, "student.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase pSQLiteDatabase) {
        pSQLiteDatabase.execSQL("create table student(id int(10),name varchar(20),className varchar(60),major varchar(60),score int(20))");
    }

    //插入数据
    public void insert(StudentBean pBean){
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("id", pBean.getId());
        values.put("name", pBean.getName());
        values.put("className", pBean.getClassName());
        values.put("major", pBean.getMajor());
        values.put("score", pBean.getScore());
        db.insert("student", null, values);
    }

    //删除数据
    public void delete(StudentBean stu){
        SQLiteDatabase db = getWritableDatabase();
        db.delete("student", "id=?", new String[]{stu.getId()+""});
    }

 	//删除表
    public void deleteTable(SQLiteDatabase db){
        db.execSQL("delete from info");
    }
    
    //修改数据
    public void update(String oldName,StudentBean pBean){
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("id", pBean.getId());
        values.put("name", pBean.getName());
        values.put("className", pBean.getClassName());
        values.put("major", pBean.getMajor());
        values.put("score", pBean.getScore());
        db.update("student", values, "name=?", new String[]{oldName});
    }

    //查询数据
    public List<StudentBean> select(){
        ArrayList<StudentBean> beans = new ArrayList<>();
        SQLiteDatabase db = getWritableDatabase();
        Cursor cursor = db.query("student", null, null, null, null, null, null);
        while (cursor.moveToNext()){
            int id = cursor.getInt(cursor.getColumnIndex("id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));
            String className = cursor.getString(cursor.getColumnIndex("className"));
            String major = cursor.getString(cursor.getColumnIndex("major"));
            int score = cursor.getInt(cursor.getColumnIndex("score"));
            beans.add(new StudentBean(id, name, className, major, score));
        }
        return beans;
    }
    
    @Override
    public void onUpgrade(SQLiteDatabase pSQLiteDatabase, int pI, int pI1) {

    }
}

添加数据和查询数据是最简单的，直接调用添加、查询的方法就行。

删除：以ListView为例，长按点击条目的时候调用数据库删除的方法，数据库删除后，列表也得删除数据

listview.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> pAdapterView, View pView, int pI, long pL) {
                mDatabase.delete(mDatabase.select().get(pI));
                mAdapter.delete(pI);
                Toast.makeText(HomeActivity.this, "删除成功", Toast.LENGTH_SHORT).show();
                return true;
            }
        });

适配器删除：

public void delete(int pos){
        mBeans.remove(pos);
        notifyDataSetChanged();
    }

修改：

listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> pAdapterView, View pView, int pI, long pL) {
                pos = pI;
                Intent intent = new Intent(HomeActivity.this,UpdateActivity.class);
                //点击的条目内容传到修改页面，修改页面修改完之后把修改的数据传过来就行
                intent.putExtra("data", mDatabase.select().get(pI));
                startActivityForResult(intent,UPDATE_TYPE);
            }
        });

这两段代码在一个页面，修改页面的传值这里没有体现

if(requestCode == UPDATE_TYPE && resultCode == 300){
            //获取修改完的数据
            StudentBean bean = (StudentBean) data.getSerializableExtra("bean");
            StudentBean studentBean = mDatabase.select().get(pos);
            List<StudentBean> select = mDatabase.select();
            select.set(pos, bean);
            mAdapter.loadBeans(select);
            mDatabase.update(studentBean.getId()+"", bean);
            mDatabase.update(studentBean.getName(), bean);
            mDatabase.update(studentBean.getClassName(), bean);
            mDatabase.update(studentBean.getMajor(), bean);
            mDatabase.update(studentBean.getScore()+"", bean);
        }

//删除表：有个出问卷调查的功能，之后需要把问卷调查的数据都删除

InfoDatabase database = newd InfoDatabase(this);
SQLiteDatabase writableDatabase = database .getWritableDatabase();
database .delete(writableDatabase);