一、修改布局文件
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:orientation="vertical"
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" tools:context=".MainActivity">
<Button android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="新建数据表" />
<Button android:id="@+id/button5"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="查询数据库" />
<Button android:id="@+id/button3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="添加两条数据" />
<Button android:id="@+id/button4"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="删除一条数据" />
<Button android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="删除数据表" />
</LinearLayout>
二、修改MainActivity文件
package com.example.yxp.usersql;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class MainActivity extends Activity {
OnClickListener listener1 = null;
OnClickListener listener2 = null;
OnClickListener listener3 = null;
OnClickListener listener4 = null;
OnClickListener listener5 = null;
Button button1;
Button button2;
Button button3;
Button button4;
Button button5;
DatabaseHelper mOpenHelper;
private static final String DATABASE_NAME = "dbForTest.db";
private static final int DATABASE_VERSION = 1;
private static final String TABLE_NAME = "diary";
private static final String TITLE = "title";
private static final String BODY = "body";
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql = "CREATE TABLE " + TABLE_NAME + " (" + TITLE
+ " text not null, " + BODY + " text not null " + ");";
Log.i("haiyang:createDB=", sql);
db.execSQL(sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
prepareListener();
initLayout();
mOpenHelper = new DatabaseHelper(this);
}
private void initLayout() {
button1 = (Button) findViewById(R.id.button1);
button1.setOnClickListener(listener1);
button2 = (Button) findViewById(R.id.button2);
button2.setOnClickListener(listener2);
button3 = (Button) findViewById(R.id.button3);
button3.setOnClickListener(listener3);
button4 = (Button) findViewById(R.id.button4);
button4.setOnClickListener(listener4);
button5 = (Button) findViewById(R.id.button5);
button5.setOnClickListener(listener5);
}
private void prepareListener() {
listener1 = new OnClickListener() {
public void onClick(View v) {
CreateTable();
}
};
listener2 = new OnClickListener() {
public void onClick(View v) {
dropTable();
}
};
listener3 = new OnClickListener() {
public void onClick(View v) {
insertItem();
}
};
listener4 = new OnClickListener() {
public void onClick(View v) {
deleteItem();
}
};
listener5 = new OnClickListener() {
public void onClick(View v) {
showItems();
}
};
}
/*
* 重新建立数据表
*/
private void CreateTable() {
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
String sql = "CREATE TABLE " + TABLE_NAME + " (" + TITLE
+ " text not null, " + BODY + " text not null " + ");";
Log.i("haiyang:createDB=", sql);
try {
db.execSQL("DROP TABLE IF EXISTS diary");
db.execSQL(sql);
setTitle("重建表成功");
} catch (SQLException e) {
setTitle("重建表错误");
}
}
/*
* 删除数据表
*/
private void dropTable() {
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
String sql = "drop table " + TABLE_NAME;
try {
db.execSQL(sql);
setTitle("删除成功:" + sql);
} catch (SQLException e) {
setTitle("删除错误");
}
}
/*
* 插入两条数据
*/
private void insertItem() {
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
String sql1 = "insert into " + TABLE_NAME + " (" + TITLE + ", " + BODY
+ ") values('AA', 'android很好');";
String sql2 = "insert into " + TABLE_NAME + " (" + TITLE + ", " + BODY
+ ") values('BB', 'android很好');";
try {
Log.i("haiyang:sql1=", sql1);
Log.i("haiyang:sql2=", sql2);
db.execSQL(sql1);
db.execSQL(sql2);
setTitle("插入成功");
} catch (SQLException e) {
setTitle("插入失败");
}
}
/*
* 删除其中的一条数据
*/
private void deleteItem() {
try {
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
db.delete(TABLE_NAME, " title = 'AA'", null);
setTitle("删除了一条title为AA的一条记录");
} catch (SQLException e) {
}
}
/*
* 在屏幕的title区域显示当前数据表当中的数据的条数。
*/
private void showItems() {
SQLiteDatabase db = mOpenHelper.getReadableDatabase();
String col[] = { TITLE, BODY };
Cursor cur = db.query(TABLE_NAME, col, null, null, null, null, null);
Log.d("lcc",cur.getColumnName(1));
Integer num = cur.getCount();
setTitle(Integer.toString(num) + " 条记录");
}
}
三、效果