SQLite数据库存储

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Update data
更新数据
Delete data
删除数据
Query data
这里写图片描述
MainActivity.class

package com.superxingyun.mydatabasehelper;import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.Toast;public class MainActivity extends AppCompatActivity {    private MyDatabaseHelper dbHelper;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        dbHelper = new MyDatabaseHelper(this, "Book_Store.db", null, 2);        Button create_database = (Button) findViewById(R.id.create_database);        Button add_data = (Button) findViewById(R.id.add_data);        Button update_data = (Button) findViewById(R.id.update_data);        Button delete_data = (Button) findViewById(R.id.delete_data);        Button query_data = (Button) findViewById(R.id.query_data);        //Create db        create_database.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                dbHelper.getWritableDatabase();            }        });        //Insert data        add_data.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                SQLiteDatabase db = dbHelper.getWritableDatabase();                ContentValues values = new ContentValues();                //组装第一条数据                values.put("name", "The Da Vinci Code");                values.put("author", "Dan Brown");                values.put("pages", 552);                values.put("price", 69.9);                db.insert("Book", null, values);                values.clear();//记得的清空                //组装第二条数据                values.put("name", "The Lost Symbo1");                values.put("author", "Dan Brown");                values.put("pages", 552);                values.put("price", 9.9);                db.insert("Book", null, values);                Toast.makeText(MainActivity.this, "Insert data", Toast.LENGTH_SHORT).show();            }        });        //Update data        update_data.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                SQLiteDatabase db = dbHelper.getWritableDatabase();                ContentValues values = new ContentValues();                values.put("price", 1.99);                db.update("Book", values, "name = ?", new String[]{"The Da Vinci Code"});                Toast.makeText(MainActivity.this, "Update data", Toast.LENGTH_SHORT).show();            }        });        //Delete data        delete_data.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                SQLiteDatabase db = dbHelper.getWritableDatabase();                db.delete("Book", "price > ?", new String[] { "5" });                Toast.makeText(MainActivity.this, "Delete data", Toast.LENGTH_SHORT).show();            }        });        //Query data        query_data.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                SQLiteDatabase db = dbHelper.getWritableDatabase();                //查询所有数据                Cursor cursor = db.query("Book", null, null, null, null, null, null);                if (cursor.moveToFirst()) {                    do {                        //遍历所有Curse对象                        String name =cursor.getString(cursor.getColumnIndex("name"));                        String author = cursor.getString(cursor.getColumnIndex("author"));                        int pages = cursor.getInt(cursor.getColumnIndex("pages"));                        double price = cursor.getDouble(cursor.getColumnIndex("price"));                        Log.i("info", "Book name is:" + name);                        Log.i("info", "Book author is:" + author);                        Log.i("info", "Book pages is:" + pages);                        Log.i("info", "Book price is:" + price);                    } while (cursor.moveToNext());                }                cursor.close();//关闭游标            }        });    }}

MyDatabaseHelper.class

package com.superxingyun.mydatabasehelper;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.widget.Toast;/* * Created by 月满轩尼诗 on 2016/10/8. */public class MyDatabaseHelper extends SQLiteOpenHelper {    public static final String CREATE_BOOK = "create table Book("        + "id integer primary key autoincrement,"        + "author text,"        + "price real,"        + "pages integer,"        + "name text)";    public static final String CREATE_CATEGORY = "create table Category("            + "id integer primary key autoincrement,"            + "category_name text,"            + "category_code integer)";    private Context mContext;    public MyDatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {        super(context, name, factory, version);        mContext = context;    }    @Override    public void onCreate(SQLiteDatabase sqLiteDatabase) {        sqLiteDatabase.execSQL(CREATE_BOOK);        sqLiteDatabase.execSQL(CREATE_CATEGORY);        Toast.makeText(mContext, "Create succeeded.", Toast.LENGTH_SHORT).show();    }    @Override    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {        sqLiteDatabase.execSQL("drop table if exists Book");        sqLiteDatabase.execSQL("drop table if exists Category");        onCreate(sqLiteDatabase);    }}

布局就是几个按钮，学习记录

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