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"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

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

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

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

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

<TextView
android:id="@+id/sex_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layou
4000
t_margin="5dp"
android:textSize="18sp" />

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

</LinearLayout>

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

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

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

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

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

</LinearLayout>

</LinearLayout>activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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">

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

<Button
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" />

<Button
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" />

<Button
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" />

<Button
android:id="@+id/bt3"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:onClick="onClic
20000
k"
android:text="查询3" />

<Button
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" />

</LinearLayout>

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

<Button
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" />

<Button
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" />

<Button
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" />

<Button
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" />

<Button
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" />

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

}
}
}