Android SQLite 数据库操作示例 - 学生信息管理

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 Datahelper datahelper;
    private SQLiteDatabase writedb;
    private SQLiteDatabase readdb;
    private EditText myno, myname, mypwd, confirmpwd, myclass;
    private TextView showtx;
    private Button summitbt, querybt;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        b1=findViewById(R.id.dqcr);
        b2=findViewById(R.id.fzzt);
        b3=findViewById(R.id.sql);
        b4=findViewById(R.id.sj);

        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);

        summitbt = findViewById(R.id.zhu1);
        querybt = findViewById(R.id.cha1);

        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) {
                Intent instant = new Intent(MainActivity.this,zscgActivity.class);
                startActivity(instant);
            }
        });

        summitbt.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();
                }
            }
        });

        querybt.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(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),stuClass 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) {

    }

}