第十周 增删改查

package com.example.bbb;
import android.os.Bundle;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    public void add(View v) {
        StuOpenHelper helper = new StuOpenHelper(this);
        SQLiteDatabase db = helper.getWritableDatabase();
        String name = ((EditText) findViewById(R.id.et_name)).getText()
                .toString();
        int age = Integer.parseInt(((EditText) findViewById(R.id.et_age))
                .getText().toString());
        db.execSQL("insert into stuinfo (name,age) values(?,?)", new Object[] {
                name, age });
        Toast.makeText(this, "ok", 0).show();
    }
    public void delete(View view) {
        StuOpenHelper helper = new StuOpenHelper(this);
        SQLiteDatabase db = helper.getWritableDatabase();
        db.execSQL("delete from stuinfo where _id=?", new Object[] { 2 });
        Toast.makeText(this, "删除成功", 0).show();
    }
    public void update(View view) {
        StuOpenHelper helper = new StuOpenHelper(this);
        SQLiteDatabase db = helper.getWritableDatabase();
        db.execSQL("update stuinfo set name=? where _id=?", new Object[] {
                "micky", 3 });
        Toast.makeText(this, "修改成功", 0).show();
    }

    public void search(View view) {
        StuOpenHelper helper = new StuOpenHelper(this);
        SQLiteDatabase db = helper.getWritableDatabase();
        String s = "";
        Cursor cursor = db.rawQuery("select * from stuinfo", null);
        if (cursor.getCount() != 0) {

            while (cursor.moveToNext()) {
                s += cursor.getInt(0) + "   " + cursor.getString(1) + "   "
                        + cursor.getInt(2) + "
";
            }
        }
        ((TextView) (findViewById(R.id.tv_show))).setText(s);
    }
}

　　

package com.example.bbb;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class StuOpenHelper extends SQLiteOpenHelper {
    public StuOpenHelper(Context context) {
        super(context, "stu.db", null, 1);
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table stuinfo(_id integer primary key autoincrement,name varchar(20),age integer)");
    }
    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
    }
}

　　

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout android:padding="16dp" android:orientation="vertical" android:background="@drawable/bg" android:layout_height="match_parent" android:layout_width="match_parent" xmlns:android="http://schemas.android.com/apk/res/android">
    <LinearLayout android:layout_height="wrap_content" android:layout_width="match_parent" android:layout_marginTop="130dp">
        <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textSize="18sp" android:text="姓 名 ："/>
        <EditText android:layout_height="wrap_content" android:layout_width="match_parent" android:textSize="16sp" android:hint="请输入姓名" android:id="@+id/et_name"/>
    </LinearLayout>
    -<LinearLayout android:layout_height="wrap_content" android:layout_width="match_parent" android:layout_marginBottom="10dp">
    <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:textSize="18sp" android:text="年 龄："/>
    <EditText android:layout_height="wrap_content" android:layout_width="match_parent" android:textSize="16sp" android:hint="输入年龄" android:id="@+id/et_age"/>
</LinearLayout>
    -<LinearLayout android:layout_height="wrap_content" android:layout_width="match_parent">
    <Button android:background="#B9B9FF" android:layout_height="wrap_content" android:layout_width="0dp" android:textSize="18sp" android:text="添加" android:id="@+id/btn_add" android:onClick="add" android:layout_weight="1" android:layout_marginRight="2dp"/>
    <Button android:background="#DCB5FF" android:layout_height="wrap_content" android:layout_width="0dp" android:textSize="18sp" android:text="查询" android:id="@+id/btn_query" android:onClick="search" android:layout_weight="1" android:layout_marginRight="2dp"/>
    <Button android:background="#E6CAFF" android:layout_height="wrap_content" android:layout_width="0dp" android:textSize="18sp" android:text="修改" android:id="@+id/btn_update" android:onClick="update" android:layout_weight="1" android:layout_marginRight="2dp"/>
    <Button android:background="#ACD6FF" android:layout_height="wrap_content" android:layout_width="0dp" android:textSize="18sp" android:text="删除" android:id="@+id/btn_delete" android:onClick="delete" android:layout_weight="1"/>
</LinearLayout>
    -<ScrollView android:layout_height="wrap_content" android:layout_width="match_parent">
    <TextView android:layout_height="wrap_content" android:layout_width="match_parent" android:layout_marginTop="25dp" android:textSize="20sp" android:id="@+id/tv_show"/>
</ScrollView>
</LinearLayout>