SQLHelper

public class DBHelper extends SQLiteOpenHelper {

static String name="shuai.db";
static  int version=1;
public DBHelper(Context context) {                     //构造函数的name和version提到外面方便调用
super(context, name, null, version);
}

@Override
public void onCreate(SQLiteDatabase db) {              //创建数据库的表，可以创建多个表
db.execSQL("create table shuai(name text PRIMARY KEY autoincrement"); //name属性为主键并自增

}

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

}
}

public class ShuaiDB {
Context context;
SQLiteDatabase db;
List<Shuai> list;

public ShuaiDB(Context context) {
this.context = context;

DBHelper sdb=new DBHelper(context);
db=sdb.getReadableDatabase();
}
//增加
public  void add(){
ContentValues cv=new ContentValues();
cv.put("name","shuai");
cv.put("value","1000");
db.insert("shuai","name",cv);                        //"shuai"为表名,"name"为主键
}

//删除
public  void del(String name){
if(cheak(name)){
db.delete("shuai","name=?",new String[]{name});
}
else{
Toast.makeText(context,"查无此人",Toast.LENGTH_LONG).show();
}
}
//修改
public void gai(String beforename){
ContentValues cv=new ContentValues();
cv.put("name","shuai2");
cv.put("value","2000");
db.update("shuai",cv,"name=?",new String[]{beforename});
}

//查询
public List search(){
list=new ArrayList<>();
Cursor cursor;
cursor=db.rawQuery("select *from shuai",null);
if(cursor!=null){
while (cursor.moveToNext()){
String name=cursor.getString(cursor.getColumnIndex("name"));
String value=cursor.getString(cursor.getColumnIndex("value"));
Shuai ss=new Shuai(name,value);
list.add(ss);
}
}
return  list;
}

//判断是否存在name
boolean cheak(String name){
Cursor cursor;
cursor=db.rawQuery("select *from shuai where name=?",new String[]{name});
if(cursor.moveToNext()){
return true;
}
return  false;
}
}

public class Home extends BaseActivity implements View.OnClickListener{
Button add,del,xiu,search;
List<Shuai> list;
ShuaiDB sdb;
TextView show;
@Override
public void setview() {
sdb=new ShuaiDB(this);
setContentView(R.layout.home);
add= (Button) findViewById(R.id.add);
del= (Button) findViewById(R.id.del);
xiu= (Button) findViewById(R.id.gai);
search= (Button) findViewById(R.id.search);
show= (TextView) findViewById(R.id.show);
}

@Override
public void inview() {
add.setOnClickListener(this);
del.setOnClickListener(this);
xiu.setOnClickListener(this);
search.setOnClickListener(this);
}

@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.add:
sdb.add();
break;
case R.id.del:
sdb.del("shuai");
break;
case R.id.gai:
sdb.gai("shuai");
break;
case R.id.search:
list=sdb.search();
show.setText(list.toString()+list.size()+"");
break;
}
}
}