SQLite数据库数据查询练习

题目：

(1) 向表中插入20条数据  (10分)
(2) 查询学生表所有信息   (10分)
(3) 查询学生表信息，只显示名字，院系，和学号  (10分)
(4) 查询显示计算机和英语系学生的成绩   (10分)
(5) 查询18-22岁学生的成绩   (10分)
(6) 查询表中有共有多少条数据  (10分)
(7) 查询成绩表中分数最高的学生信息   (10分)
(8) 查询显示名字叫李四的学生信息   (10分)
(9) 查询语文成绩的总和   (10分)
(10) 查询英语平均成绩   (10分)

效果图：

项目结构：

布局文件代码：

item_layout.xml:

xml version="1.0" encoding="utf-8"?>
xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

            android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

                    android:id="@+id/code_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:textSize="18sp" />

                    android:id="@+id/name_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:textSize="18sp" />

                    android:id="@+id/age_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:textSize="18sp" />

                    android:id="@+id/sex_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:textSize="18sp" />

                    android:id="@+id/birth_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:textSize="18sp" />


    

            android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

                    android:id="@+id/department_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:textSize="18sp" />

                    android:id="@+id/address_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:textSize="18sp" />

                    android:id="@+id/chineseCode_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:textSize="18sp" />

                    android:id="@+id/englishCode_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:textSize="18sp" />


    

activity_main.xml:

xml version="1.0" encoding="utf-8"?>
xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.mrzhao.sqlitedemo2.MainActivity">

            android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

                    android:id="@+id/insert_bt"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="插入" />

                    android:id="@+id/bt1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="查询1" />

                    android:id="@+id/bt2"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="查询2" />

                    android:id="@+id/bt3"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="查询3" />

                    android:id="@+id/bt4"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="查询4" />


    

            android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

                    android:id="@+id/bt5"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="查询5" />


                    android:id="@+id/bt6"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="查询6" />

                    android:id="@+id/bt7"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="查询7" />

                    android:id="@+id/bt8"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="查询8" />

                    android:id="@+id/bt9"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="查询9" />


    
    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent">ListView>

db包下：

Config文件:

public class Config {
    //数据库的名字
    public static final String DATABASE_NAME = "student.db";
    //表名
    public static final String TABLE_NAME = "student";
    //数据库版本号
    public static final int DB_VERSION = 1;

}

SQLiteHelper文件：

public class SQLiteHelper extends SQLiteOpenHelper {
    public SQLiteHelper(Context context) {
        super(context, Config.DATABASE_NAME, null, Config.DB_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        //创建表：
        db.execSQL("create table if not exists student(_id integer primary key autoincrement,Id INT(10),name VARCHAR(10),age INT(4),sex VARCHAR(10),birth VARCHAR(10),department VARCHAR(10),address VARCHAR(100),chinesScore DOUBLE(10),englishScore DOUBLE(10))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

DBUtils文件:

public class DBUtils {
    private Context context;
    private SQLiteHelper helper;

    //最好使用单例模式
    public DBUtils(Context context) {
        this.context = context;
        helper = new SQLiteHelper(context);
    }

    /**
     * 向表中插入一个学生
     *
     * @param student
     * @return
     */
    public boolean insertData(Student student) {
        SQLiteDatabase db = helper.getReadableDatabase();
        ContentValues values = new ContentValues();

        values.put("Id", student.getId());
        values.put("name", student.getName());
        values.put("age", student.getAge());
        values.put("sex", student.getSex());
        values.put("birth", student.getBirth());
        values.put("department", student.getDepartment());
        values.put("address", student.getAddress());
        values.put("chinesScore", student.getChinesScore());
        values.put("englishScore", student.getEnglishScore());
        long insert = db.insert(Config.TABLE_NAME, null, values);
        if (insert > 0) {
            return true;
        }

        return false;
    }

    /**
     * 查询全部的学生数据信息
     *
     * @return
     */
    public List<Student> getAllStudent() {
        List<Student> list = new ArrayList<>();
        SQLiteDatabase db = helper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from " + Config.TABLE_NAME, null);
        if (cursor != null && cursor.getCount() > 0) {
            while (cursor.moveToNext()) {

                int id = cursor.getInt(cursor.getColumnIndex("Id"));
                String name = cursor.getString(cursor.getColumnIndex("name"));
                int age = cursor.getInt(cursor.getColumnIndex("age"));
                String sex = cursor.getString(cursor.getColumnIndex("sex"));
                String birth = cursor.getString(cursor.getColumnIndex("birth"));
                String department = cursor.getString(cursor.getColumnIndex("department"));
                String address = cursor.getString(cursor.getColumnIndex("address"));
                double chinesScore = cursor.getDouble(cursor.getColumnIndex("chinesScore"));
                double englishScore = cursor.getDouble(cursor.getColumnIndex("englishScore"));

                Student student = new Student(id, name, age, sex, birth, department, address, chinesScore, englishScore);
                list.add(student);
            }
        }

        return list;
    }

    /**
     * 查询学生表信息，只显示名字，院系，和学号
     *
     * @return
     */
    public List<Student> getStudentNameAndCode() {
        List<Student> list = new ArrayList<>();
        SQLiteDatabase db = helper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from " + Config.TABLE_NAME, null);
        if (cursor != null && cursor.getCount() > 0) {
            while (cursor.moveToNext()) {
                int id = cursor.getInt(cursor.getColumnIndex("Id"));
                String name = cursor.getString(cursor.getColumnIndex("name"));
                String department = cursor.getString(cursor.getColumnIndex("department"));
                Student student = new Student(id, name, 0, "", "", department, "", 0, 0);
                list.add(student);
            }
        }
        return list;
    }

    /**
     * 查询显示计算机和英语系学生的成绩
     *
     * @return
     */
    public List<Student> getAllStudentEnglshAndCompute() {
        List<Student> list = new ArrayList<>();
        SQLiteDatabase db = helper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from " + Config.TABLE_NAME + " where department in ('英语系' , '计算机')", null);
        if (cursor != null && cursor.getCount() > 0) {
            while (cursor.moveToNext()) {

                int id = cursor.getInt(cursor.getColumnIndex("Id"));
                String name = cursor.getString(cursor.getColumnIndex("name"));
                int age = cursor.getInt(cursor.getColumnIndex("age"));
                String sex = cursor.getString(cursor.getColumnIndex("sex"));
                String birth = cursor.getString(cursor.getColumnIndex("birth"));
                String department = cursor.getString(cursor.getColumnIndex("department"));
                String address = cursor.getString(cursor.getColumnIndex("address"));
                double chinesScore = cursor.getDouble(cursor.getColumnIndex("chinesScore"));
                double englishScore = cursor.getDouble(cursor.getColumnIndex("englishScore"));

                Student student = new Student(id, name, age, sex, birth, department, address, chinesScore, englishScore);
                list.add(student);
            }
        }

        return list;
    }


    /**
     * 查询18-22岁学生的成绩
     *
     * @return
     */
    public List<Student> getAllStudentAge() {
        List<Student> list = new ArrayList<>();
        SQLiteDatabase db = helper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from " + Config.TABLE_NAME + " where age > 18 and age < 22", null);
        if (cursor != null && cursor.getCount() > 0) {
            while (cursor.moveToNext()) {

                int id = cursor.getInt(cursor.getColumnIndex("Id"));
                String name = cursor.getString(cursor.getColumnIndex("name"));
                int age = cursor.getInt(cursor.getColumnIndex("age"));
                String sex = cursor.getString(cursor.getColumnIndex("sex"));
                String birth = cursor.getString(cursor.getColumnIndex("birth"));
                String department = cursor.getString(cursor.getColumnIndex("department"));
                String address = cursor.getString(cursor.getColumnIndex("address"));
                double chinesScore = cursor.getDouble(cursor.getColumnIndex("chinesScore"));
                double englishScore = cursor.getDouble(cursor.getColumnIndex("englishScore"));

                Student student = new Student(id, name, age, sex, birth, department, address, chinesScore, englishScore);
                list.add(student);
            }
        }

        return list;
    }

    /**
     * 查询表中有共有多少条数据
     *
     * @return
     */
    public int getStudentCount() {
        SQLiteDatabase db = helper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from " + Config.TABLE_NAME, null);
        return cursor.getCount();
    }

    /**
     * 查询成绩表中分数最高的学生信息
     */
    public List<Student> getAllStudentScore() {
        List<Student> list = new ArrayList<>();
        SQLiteDatabase db = helper.getReadableDatabase();
        //降序的方式排列查询数据desc    升序 asc
        Cursor cursor = db.rawQuery("select * from " + Config.TABLE_NAME + " order by chinesScore desc", null);
        if (cursor != null && cursor.getCount() > 0) {
            //取出第一个 就是最高分
            while (cursor.moveToFirst()) {
                int id = cursor.getInt(cursor.getColumnIndex("Id"));
                String name = cursor.getString(cursor.getColumnIndex("name"));
                int age = cursor.getInt(cursor.getColumnIndex("age"));
                String sex = cursor.getString(cursor.getColumnIndex("sex"));
                String birth = cursor.getString(cursor.getColumnIndex("birth"));
                String department = cursor.getString(cursor.getColumnIndex("department"));
                String address = cursor.getString(cursor.getColumnIndex("address"));
                double chinesScore = cursor.getDouble(cursor.getColumnIndex("chinesScore"));
                double englishScore = cursor.getDouble(cursor.getColumnIndex("englishScore"));

                Student student = new Student(id, name, age, sex, birth, department, address, chinesScore, englishScore);
                list.add(student);
                break;
            }
        }
        return list;
    }

    /**
     * 查询显示名字叫李四的学生信息
     *
     * @return
     */
    public List<Student> getStudentLisi() {
        List<Student> list = new ArrayList<>();
        SQLiteDatabase db = helper.getReadableDatabase();

        Cursor cursor = db.rawQuery("select * from " + Config.TABLE_NAME + " where name =  '李四'", null);
        if (cursor != null && cursor.getCount() > 0) {
            while (cursor.moveToFirst()) {
                int id = cursor.getInt(cursor.getColumnIndex("Id"));
                String name = cursor.getString(cursor.getColumnIndex("name"));
                int age = cursor.getInt(cursor.getColumnIndex("age"));
                String sex = cursor.getString(cursor.getColumnIndex("sex"));
                String birth = cursor.getString(cursor.getColumnIndex("birth"));
                String department = cursor.getString(cursor.getColumnIndex("department"));
                String address = cursor.getString(cursor.getColumnIndex("address"));
                double chinesScore = cursor.getDouble(cursor.getColumnIndex("chinesScore"));
                double englishScore = cursor.getDouble(cursor.getColumnIndex("englishScore"));

                Student student = new Student(id, name, age, sex, birth, department, address, chinesScore, englishScore);
                list.add(student);
                break;
            }
        }
        return list;
    }


    /**
     * 获取语文成绩的总和
     *
     * @return
     */
    public double getAllStudentChineseScoreTotal() {

        double total = 0;
        SQLiteDatabase db = helper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from " + Config.TABLE_NAME, null);
        if (cursor != null && cursor.getCount() > 0) {
            while (cursor.moveToNext()) {
                double chinesScore = cursor.getDouble(cursor.getColumnIndex("chinesScore"));
                total += chinesScore;
            }
        }
        return total;
    }

    /**
     * 获取英语的平均成绩
     * @return
     */
    public double getAllStudentEnglishScore() {

        double total = 0;
        SQLiteDatabase db = helper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from " + Config.TABLE_NAME, null);
        if (cursor != null && cursor.getCount() > 0) {
            while (cursor.moveToNext()) {
                double englishScore = cursor.getDouble(cursor.getColumnIndex("englishScore"));
                total += englishScore;
            }
        }
        return total/cursor.getCount();
    }

}

Student自定义学生类文件：

public class Student {

    private int Id;
    private String name;
    private int age;
    private String sex;
    private String birth;
    private String department;
    private String address;
    private double chinesScore;
    private double englishScore;


    public Student(int id, String name, int age, String sex, String birth, String department, String address, double chinesScore, double englishScore) {
        Id = id;
        this.name = name;
        this.age = age;
        this.sex = sex;
        this.birth = birth;
        this.department = department;
        this.address = address;
        this.chinesScore = chinesScore;
        this.englishScore = englishScore;
    }

    public int getId() {
        return Id;
    }

    public void setId(int id) {
        Id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getBirth() {
        return birth;
    }

    public void setBirth(String birth) {
        this.birth = birth;
    }

    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public double getChinesScore() {
        return chinesScore;
    }

    public void setChinesScore(double chinesScore) {
        this.chinesScore = chinesScore;
    }

    public double getEnglishScore() {
        return englishScore;
    }

    public void setEnglishScore(double englishScore) {
        this.englishScore = englishScore;
    }

    @Override
    public String toString() {
        return "Student{" +
                "Id=" + Id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                ", birth='" + birth + '\'' +
                ", department='" + department + '\'' +
                ", address='" + address + '\'' +
                ", chinesScore=" + chinesScore +
                ", englishScore=" + englishScore +
                '}';
    }
}

MyAdapter适配器文件：

public class MyAdapter extends BaseAdapter {
    private List<Student> list;
    private Context context;
    private LayoutInflater inflater;

    public MyAdapter(List<Student> list, Context context) {
        this.list = list;
        this.context = context;
        inflater = LayoutInflater.from(context);
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        if (convertView == null) {
            holder = new ViewHolder();
            convertView = inflater.inflate(R.layout.item_layout, parent, false);

            holder.codeTv = (TextView) convertView.findViewById(R.id.code_tv);
            holder.nameTv = (TextView) convertView.findViewById(R.id.name_tv);
            holder.ageTv = (TextView) convertView.findViewById(R.id.age_tv);
            holder.sexTv = (TextView) convertView.findViewById(R.id.sex_tv);
            holder.birthTv = (TextView) convertView.findViewById(R.id.birth_tv);
            holder.departmentTv = (TextView) convertView.findViewById(R.id.department_tv);
            holder.addressTv = (TextView) convertView.findViewById(R.id.address_tv);
            holder.chineseTv = (TextView) convertView.findViewById(R.id.chineseCode_tv);
            holder.englishTv = (TextView) convertView.findViewById(R.id.englishCode_tv);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }
        Student student = list.get(position);

        holder.codeTv.setText(student.getId() + "");
        holder.nameTv.setText(student.getName());
        holder.ageTv.setText(student.getAge() + "");
        holder.sexTv.setText(student.getSex());
        holder.birthTv.setText(student.getBirth());
        holder.departmentTv.setText(student.getDepartment());
        holder.addressTv.setText(student.getAddress());
        holder.chineseTv.setText(student.getChinesScore() + "");
        holder.englishTv.setText(student.getEnglishScore() + "");


        return convertView;
    }

    static class ViewHolder {
        TextView codeTv, nameTv, ageTv, sexTv, birthTv, departmentTv, addressTv, chineseTv, englishTv;
    }
}

MainActivity：

public class MainActivity extends AppCompatActivity {

    private ListView listView;
    private DBUtils dbUtils;
    private List<Student> list = new ArrayList<>();
    private MyAdapter myAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView = (ListView) findViewById(R.id.listView);
        dbUtils = new DBUtils(this);
        myAdapter = new MyAdapter(list, this);
        listView.setAdapter(myAdapter);

    }

    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.insert_bt:
                //插入20条数据

                dbUtils.insertData(new Student(1001, "张三", 16, "男", "1989", "英语系", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "李四", 21, "男", "1989", "体育系", "北京市", 10, 90));
                dbUtils.insertData(new Student(1001, "李四", 122, "男", "1989", "计算机", "北京市", 200, 90));
                dbUtils.insertData(new Student(1001, "王五", 18, "男", "1989", "计算机", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "赵六", 19, "男", "1989", "体育系", "北京市", 140, 90));
                dbUtils.insertData(new Student(1001, "呵呵", 22, "女", "1989", "计算机", "北京市", 150, 90));
                dbUtils.insertData(new Student(1001, "嘻嘻", 21, "男", "1989", "体育系", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "大师兄", 28, "男", "1989", "计算机", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "沙师弟", 20, "女", "1989", "语文系", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "师傅", 18, "男", "1989", "英语系", "北京市", 160, 90));
                dbUtils.insertData(new Student(1001, "白龙马", 19, "男", "1989", "语文系", "北京市", 100, 90));

                dbUtils.insertData(new Student(1001, "猪八戒", 20, "女", "1989", "英语系", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "你好", 22, "男", "1989", "英语系", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "马云", 967, "男", "1989", "体育系", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "马化腾", 6, "女", "1989", "语文系", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "张朝阳", 457, "男", "1989", "英语系", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "周鸿祎", 23, "男", "1989", "计算机", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "李彦宏", 64, "男", "1989", "体育系", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "王健林", 23, "男", "1989", "计算机", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "张磊", 14, "男", "1989", "语文系", "北京市", 100, 90));
                dbUtils.insertData(new Student(1001, "柴伟", 16, "男", "1989", "体育系", "北京市", 100, 90));


                break;
            case R.id.bt1:
                //查询学生表所有信息
                List<Student> allStudent = dbUtils.getAllStudent();
                list.clear();
                list.addAll(allStudent);
                myAdapter.notifyDataSetChanged();
                break;
            case R.id.bt2:
                // 查询学生表信息，只显示名字，院系，和学号
                List<Student> list1 = dbUtils.getStudentNameAndCode();
                list.clear();
                list.addAll(list1);
                myAdapter.notifyDataSetChanged();
                break;
            case R.id.bt3:
                //  查询显示计算机和英语系学生的成绩
                List<Student> list2 = dbUtils.getAllStudentEnglshAndCompute();
                list.clear();
                list.addAll(list2);
                myAdapter.notifyDataSetChanged();
                break;
            case R.id.bt4:
                // 查询18-22岁学生的成绩
                List<Student> list3 = dbUtils.getAllStudentAge();
                list.clear();
                list.addAll(list3);
                myAdapter.notifyDataSetChanged();
                break;
            case R.id.bt5:
                // 查询表中有共有多少条数据
                int studentCount = dbUtils.getStudentCount();
                Toast.makeText(this, "" + studentCount, Toast.LENGTH_SHORT).show();
                break;
            case R.id.bt6:
                //查询成绩表中分数最高的学生信息
                List<Student> list4 = dbUtils.getAllStudentScore();
                list.clear();
                list.addAll(list4);
                myAdapter.notifyDataSetChanged();
                break;
            case R.id.bt7:
                //查询显示名字叫李四的学生信息
                List<Student> list5 = dbUtils.getStudentLisi();
                list.clear();
                list.addAll(list5);
                myAdapter.notifyDataSetChanged();
                break;
            case R.id.bt8:
                // 查询语文成绩的总和
                double cs = dbUtils.getAllStudentChineseScoreTotal();
                Toast.makeText(this, ""+cs, Toast.LENGTH_SHORT).show();
                break;
            case R.id.bt9:
                //查询英语平均成绩
                double es = dbUtils.getAllStudentEnglishScore();
                Toast.makeText(this, ""+es, Toast.LENGTH_SHORT).show();

                break;

        }
    }
}