Android SQLite 数据库操作：学生信息管理系统

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; import android.widget.Toast;

public class MainActivity extends AppCompatActivity { private Button b1, b2, b3, b4; private EditText myno, myname, mypwd, confirmpwd, myclass; private TextView showtx; private Datahelper datahelper; private SQLiteDatabase writedb; private SQLiteDatabase readdb;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    datahelper = new Datahelper(this);
    writedb = datahelper.getWritableDatabase();
    readdb = datahelper.getReadableDatabase();

    myno = findViewById(R.id.xuehao1);
    myname = findViewById(R.id.xingm);
    mypwd = findViewById(R.id.mima1);
    confirmpwd = findViewById(R.id.queren);
    myclass = findViewById(R.id.banji);
    showtx = findViewById(R.id.jbxx);

    b1 = findViewById(R.id.dqcr);
    b2 = findViewById(R.id.fzzt);
    b3 = findViewById(R.id.sql);
    b4 = findViewById(R.id.sj);

    b1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent instant = new Intent(MainActivity.this, dqcrActivity.class);
            startActivity(instant);
        }
    });
    b2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent instant = new Intent(MainActivity.this, fzztActivity.class);
            startActivity(instant);
        }
    });
    b3.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent instant = new Intent(MainActivity.this, SQLActivity.class);
            startActivity(instant);
        }
    });

    b4.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            if (mypwd.getText().toString().equals(confirmpwd.getText().toString())) {
                String insertstr = "insert into login_tb(stuNo, stuname, stupwd, stuClass) values('"+ myno.getText().toString() + "', '" + myname.getText().toString() + "', '" + mypwd.getText().toString() + "', " + Integer.parseInt(myclass.getText().toString()) + ")";
                writedb.execSQL(insertstr);
                Toast.makeText(MainActivity.this, "插入成功", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(MainActivity.this, "两次输入密码不同", Toast.LENGTH_SHORT).show();
            }
        }
    });
}

public void queryData(View view) {
    Cursor cursor = readdb.rawQuery("select * from login_tb", null);
    StringBuilder showdata = new StringBuilder();
    while (cursor.moveToNext()) {
        String newNo = cursor.getString(0);
        String newName = cursor.getString(1);
        String newpwd = cursor.getString(2);
        int newclass = cursor.getInt(3);
        showdata.append(newNo).append(" ").append(newName).append(" ").append(newpwd).append(" ").append(newclass).append("\r");
    }
    showtx.setText(showdata.toString());
    cursor.close();
}

}

import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper;

public class Datahelper extends SQLiteOpenHelper { public Datahelper(Context context) { super(context, "mydat.db", null, 1); }

public void onCreate(SQLiteDatabase sqLiteDatabase) {
    String tbstr = "create table login_tb(stuNo varchar(12) primary key, stuname varchar(20),stupwd varchar(20),stuXlass Integer)";
    sqLiteDatabase.execSQL(tbstr);
    String gradestr = "create table mark_tb(stuNo varchar(12),subject varchar(20),cent real)";
    sqLiteDatabase.execSQL(gradestr);
}

@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

}

}