Android 中 SQLite 的应用总结

通过一个demo程序测试了SQLite的语句应用。里面涉及到，数据库建立，表的建立，表中数据的添加，更改，删除，查询
1. 数据库的建立

    Android中集成了SQLite数据库，但是不回自动提供数据库，所以我们想应用的话第一步是建立自己的数据库。

    首先引入包   import android.database.sqlite.SQLiteDatabase;

    下面一句话初始化数据库，也就是建立自己命名的数据句 

    db = openOrCreateDatabase(dbName,MODE_PRIVATE,null);
2. 建立表

    执行语句是

    db.execSQL("CREATE TABLE IF NOT EXISTS mytable(id INTEGER PRIMARY KEY AUTOINCREMENT, name varchar(30), score INTEGER);");

    此语句是通过调用SQLiteDatabase的execSQL()方法，在里面书写SQL语句完成的。
3. 数据的添加、更改、删除

    添加

    db.execSQL("INSERT INTO mytable VALUES('61', 'zhang', '5');");

     更改              

    db.execSQL("UPDATE mytable SET name='pei' WHERE id='61';");

     删除             

     db.execSQL("DELETE FROM mytable WHERE id='61';");
4. 数据的查询

    查询可以通过Android的query方法，此方法会返回一个Cursor对象，通过对Cursor对象的各种操作，可以获得所需数据。

    获取对象方法

     Cursor cursor = db.query(tableName,null,null,null,null,null,null);//后面这一堆参数可缺省

    具体实现在下面JAVA代码的90-108行
5. 代码

    .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="创建数据库"

        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="创建表"

        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修改数据"

        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="查询数据"

        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 修改数据"

        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();//跳到第一个游标

            for(int i=0;i<cursor.getCount();i=
i+1){

                str = str
+ cursor.getString(0)+""+cursor.getString(1)+""+cursor.getString(2)+"\n";

                cursor.moveToNext();//下一个游标

            }

        }

        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);

    }

}

                        de