Android 中 SQLite 的應用總結

通過一個demo程序測試了SQLite的語句應用。裏面涉及到，數據庫建立，表的建立，表中數據的添加，更改，刪除，查詢
1. 數據庫的建立
    Android中集成了SQLite數據庫，但是不回自動提供數據庫，所以我們想應用的話第一步是建立自己的數據庫。
    首先引入包   import android.database.sqlite.SQLiteDatabase;
    下面一句話初始化數據庫，也就是建立自己命名的數據句 
    db = openOrCreateDatabase(dbName,MODE_PRIVATE,null);
2. 建立表
    執行語句是
    db.execSQL("CREATE TABLE IF NOT EXISTS mytable(id INTEGER PRIMARY KEY AUTOINCREMENT, name varchar(30), score INTEGER);");
    此語句是通過調用SQLiteDatabase的execSQL()方法，在裏面書寫SQL語句完成的。
3. 數據的添加、更改、刪除
    添加
    db.execSQL("INSERT INTO mytable VALUES('61', 'zhang', '5');");
     更改              
    db.execSQL("UPDATE mytable SET name='pei' WHERE id='61';");
     刪除             
     db.execSQL("DELETE FROM mytable WHERE id='61';");
4. 數據的查詢
    查詢可以通過Android的query方法，此方法會返回一個Cursor對象，通過對Cursor對象的各種操作，可以獲得所需數據。
    獲取對象方法
     Cursor cursor = db.query(tableName,null,null,null,null,null,null);//後面這一堆參數可缺省
    具體實現在下面JAVA代碼的90-108行
5. 代碼
    .XML

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<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:background="@drawable/b2"
    tools:context=".MainActivity">
    //title
    <TextView android:text="Hello SQLite!!"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/titleTextView"/>
    //create SQLite
    <Button
        android:text="創建數據庫"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/initSQL"
        android:layout_below="@+id/titleTextView"
        android:layout_marginTop="20dp"
        android:layout_alignLeft="@+id/titleTextView"
        />
    //create table
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="創建表"
        android:id="@+id/createTable"
        android:layout_below="@+id/initSQL"
        android:layout_marginTop="20dp"
        android:layout_alignLeft="@+id/titleTextView"
        />

    //Android modification data
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Android修改數據"
        android:id="@+id/AndroidModData"
        android:layout_below="@+id/createTable"
        android:layout_marginTop="20dp"
        android:layout_alignLeft="@+id/titleTextView"
        />

    //query data
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="查詢數據"
        android:id="@+id/queryData"
        android:layout_below="@+id/AndroidModData"
        android:layout_marginTop="20dp"
        android:layout_alignLeft="@+id/initSQL"
        />

    //SQL modification data
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="SQL 修改數據"
        android:id="@+id/SQLModData"
        android:layout_below="@+id/queryData"
        android:layout_marginTop="20dp"
        android:layout_alignLeft="@+id/initSQL"
        />

</RelativeLayout>

    .JAVA

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package com.example.warrior.sqliteoperator;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;


public class MainActivity
extends Activity
{

    private Button initButton;
    private Button tableButton;
    private Button btn_SqlMod;
    private Button btn_AndroidMod;
    private Button btn_Query;
    private final
String dbName =
"SQLdb";
    private final
String tableName =
"mytable";
    private SQLiteDatabase db 
= null;
    private int i
= 1;
    @Override
    protected 
void onCreate(Bundle savedInstanceState)
{
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initButton = 
(Button)findViewById(R.id.initSQL);
        initButton.setOnClickListener(new
View.OnClickListener()
{
            @Override
            public 
void onClick(View v)
{
                db = openOrCreateDatabase(dbName,MODE_PRIVATE,null);
                Toast.makeText(getApplicationContext(),"create
SQLite Success!!", 1000).show();
            }
        });

        //create table
        tableButton = 
(Button)findViewById(R.id.createTable);
        tableButton.setOnClickListener(new
View.OnClickListener()
{
            @Override
            public 
void onClick(View v)
{
                if(db
!= 
null){
                    db.execSQL("CREATE TABLE IF NOT EXISTS mytable(id INTEGER PRIMARY KEY AUTOINCREMENT, name varchar(30), score INTEGER);");
                    Toast.makeText(getApplicationContext(),"create
table success!!", 1000).show();
                }else
{
                    Toast.makeText(getApplicationContext(),"None
SQL", 1000).show();
                }
            }
        });

        //sql modification data
        btn_SqlMod = 
(Button)findViewById(R.id.SQLModData);
        btn_SqlMod.setOnClickListener(new
View.OnClickListener()
{
            @Override
            public 
void onClick(View v)
{
                if(db
!= 
null){
                    db.execSQL("INSERT INTO mytable VALUES('61', 'zhang', '5');");
                    Toast.makeText(getApplicationContext(),"ADD
SUCCESS!!",1000).show();
                    db.execSQL("UPDATE mytable SET name='pei' WHERE id='61';");
                    Toast.makeText(getApplicationContext(),
"UPDATE SUCCESS!!", 1000).show();
                    db.execSQL("DELETE FROM mytable WHERE id='61';");
                    Toast.makeText(getApplicationContext(),
"DELETE SUCCESS!!", 1000).show();
                }else
{
                    Toast.makeText(getApplicationContext(),
"NO SQL", 2000).show();
                }
            }
        });


        btn_Query = 
(Button)findViewById(R.id.queryData);
        btn_Query.setOnClickListener(new
View.OnClickListener()
{
            @Override
            public 
void onClick(View v)
{
                if(db
!= 
null){
                    queryData();
                    Toast.makeText(getApplicationContext(),
"SELECT SUCCESS!!", 2000).show();
                }else
{
                    Toast.makeText(getApplicationContext(),
"NO SQL", 2000).show();
                }
            }
        });


    }

    public void queryData(){
        Cursor 
cursor = db.query(tableName,null,null,null,null,null,null);
        String str 
= "";
        if(cursor.getCount()
!= 0){
            cursor.moveToFirst();//跳到第一個遊標
            for(int i=0;i<cursor.getCount();i=
i+1){
                str = str 
+ cursor.getString(0)+""+cursor.getString(1)+""+cursor.getString(2)+"\n";
                cursor.moveToNext();//下一個遊標
            }
        }
        new AlertDialog.Builder(MainActivity.this).setTitle("query
message!!")
                .setMessage(str)
                .setNegativeButton("yes",
new DialogInterface.OnClickListener()
{
                    @Override
                    public 
void onClick(DialogInterface 
dialog, int which)
{

                    }
                }).show();
    }


    @Override
    public boolean onCreateOptionsMenu(Menu
menu) 
{
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main,
menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem
item) 
{
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id
= item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id
== R.id.action_settings)
{
            return true;
        }

        return 
super.onOptionsItemSelected(item);
    }
}

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