SQLite數據初級修煉01

對上述要求了做了一些小修改，完成了功能即可：
1：如數據就添加了3條，一般認爲小型dome，3條就可以代表數據的一般性了
2：刪除數據就是刪除一個工資爲5000的（salary = ? 5000）
3: 修改數據就是修改 性別爲女 姓名爲Liy
4:查詢數據就是 沒什麼可說的了 遊標，規範一下子。

1：數據庫創建與幫助類

package com.ys.sqlite;


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

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

/**
 * Date:2019/12/12
 * Time:15:17
 * author:Mr_YANG SQLite 數據庫的建立與升級
 */
public class MYSQLites extends SQLiteOpenHelper {
    private  Context Mcontext;



    public MYSQLites(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
        Mcontext=context;

    }

    public  static  final  String Table_staff="CREATE TABLE staff ("
            + " _id integer primary key autoincrement ,"
            + " name text ,"
            + " sex text ,"
            + " deparment text ,"
            + " salary text"
            + ")";

    @Override
    public void onCreate(SQLiteDatabase db) {
        String sql = Table_staff;
        db.execSQL(sql);
        Toast.makeText(Mcontext,"數據庫，表創建成功",Toast.LENGTH_LONG).show();
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        String sql = "DROP TABLE IF EXISTS staff";
        db.execSQL(sql);
        Toast.makeText(Mcontext,"數據庫結構發生變化，升級",Toast.LENGTH_LONG).show();
    }
}

2：主界面 簡單的封裝一下子，不嚴謹奧。

package com.ys.sqlite;

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

import androidx.appcompat.app.AppCompatActivity;

/**
 * 楊勝：
 * [email protected]
 */
public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Button button;
    private Button button2;
    private Button button3;
    private Button button4;
    private MYSQLites mysqLites;

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

    private void initView() {
        button = (Button) findViewById(R.id.button);
        button2 = (Button) findViewById(R.id.button2);
        button3 = (Button) findViewById(R.id.button3);
        button4 = (Button) findViewById(R.id.button4);

        button.setOnClickListener(this);
        button2.setOnClickListener(this);
        button3.setOnClickListener(this);
        button4.setOnClickListener(this);
        /**
         * 實列化數據庫 test.db
         */
        mysqLites = new MYSQLites(this, "test.db", null, 1);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.button:
                add();
                break;
            case R.id.button2:
                del();
                break;
            case R.id.button3:
                upd();
                break;
            case R.id.button4:
                query();
                break;
        }
    }

    /**
     * add 數據
     */
    private void add() {
        SQLiteDatabase db = mysqLites.getWritableDatabase();
        ContentValues values = new ContentValues();
        /*1*/
        values.put("_id", 1);
        values.put("name", "Tom");
        values.put("sex", "男");
        values.put("deparment", "Computer");
        values.put("salary", "5400");
        db.insert("staff", null, values);
        values.clear();
        /*2*/
        values.put("_id", 2);
        values.put("name", "Liy");
        values.put("sex", "男");
        values.put("deparment", "Computer");
        values.put("salary", "4800");
        db.insert("staff", null, values);
        values.clear();
        /*3*/
        values.put("_id", 3);
        values.put("name", "Napoleon");
        values.put("sex", "女");
        values.put("deparment", "Computer");
        values.put("salary", "5000");
        db.insert("staff", null, values);
        values.clear();
        Toast.makeText(this, "數據：添加", Toast.LENGTH_LONG).show();

    }

    /**
     * del 數據
     */
    private void del() {
        SQLiteDatabase db = mysqLites.getReadableDatabase();
        db.delete("staff", "salary = ?", new String[]{"5000"});
        Toast.makeText(this, "數據：刪除", Toast.LENGTH_LONG).show();
    }

    /**
     * upadte 數據
     */
    private void upd() {
        SQLiteDatabase db = mysqLites.getReadableDatabase();
        ContentValues values = new ContentValues();
        values.put("sex", "女");
        db.update("staff", values, "name = ?", new String[]{"Tom"});
        Toast.makeText(this, "數據：已更新", Toast.LENGTH_LONG).show();
    }

    /**
     * query 查詢數據
     */
    private void query() {
        SQLiteDatabase db = mysqLites.getReadableDatabase();
        /*相當於 select * from staff*/
        Cursor cursor = db.query("staff", null, null, null, null, null, null);
        if (cursor.moveToFirst()) {

            do {
                int _id = cursor.getInt(cursor.getColumnIndex("_id"));
                String name = cursor.getString(cursor.getColumnIndex("name"));
                String sex = cursor.getString(cursor.getColumnIndex("sex"));
                String deparment = cursor.getString(cursor.getColumnIndex("deparment"));
                String salary = cursor.getString(cursor.getColumnIndex("salary"));
                Toast.makeText(this, "數據：" + _id + name + sex + deparment + salary, Toast.LENGTH_LONG).show();

            } while (cursor.moveToNext());

        } else {
            Toast.makeText(this, "數據：還不存在", Toast.LENGTH_LONG).show();
        }
    }
}

xml代碼沒什麼可以說的，我就不po出來了。