Android SQLite数据库的添、删、查、改(1)

来源:互联网 时间:1970-01-01

首先要创建一个类,继承自SQLiteOpenHelper,用来打开数据库(当数据库不存在时创建数据库)

package com.SQLiteTest2;

import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;

public class MyOpenHelper extends SQLiteOpenHelper {
public static final String DB_NAME = "student";
public static final String TABLE_NAME = "student_information";
public static final String ID = "_id";
public static final String NUMBER = "number";
public static final String NAME = "name";

public MyOpenHelper(Context context, String name, CursorFactory factory,
int version) {
super(context, name, factory, version);
// TODO Auto-generated constructor stub
}

@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("create table if not exists "+TABLE_NAME+" ("
+ ID + " integer primary key,"
+ NUMBER + " varchar,"
+ NAME + " varchar)");


}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub

}

}

在onCreate()函数中,我创建一个表,用来存储学生的学号和姓名信息

然后从UI上的TextEdit控件上获取数据

 main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/enter"
/>
<LinearLayout
android:orientation="horizontal"
android:id="@+id/LinearLayout01"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/number"
/>
<EditText
android:id="@+id/number"
android:layout_width="fill_parent"
android:layout_height="wrap_content"></EditText>
</LinearLayout>

<LinearLayout
android:orientation="horizontal"
android:id="@+id/LinearLayout02"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/name"
/>
<EditText
android:id="@+id/name"
android:layout_width="fill_parent"
android:layout_height="wrap_content"></EditText>
</LinearLayout>
<Button
android:id="@+id/submit"
android:text="@string/submit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"></Button>
<TextView
android:id="@+id/IdLongitude"
android:textSize="16px"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<TextView
android:id="@+id/IdLatitude"
android:textSize="16px"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>

接下来就是主窗体的代码部分了

主窗体部分代码
import static com.SQLiteTest2.MyOpenHelper.*;
public class SQLiteTest2 extends Activity {
MyOpenHelper myHelper;
EditText [] textArray;
Button btn_save;
int [] textIds = {
R.id.number,
R.id.name
};
View.OnClickListener myListener = new View.OnClickListener() {
@Override
public void onClick(View v) { //保存按钮按下触发该事件
String [] strArray = new String[textArray.length];
for(int i = 0; i < strArray.length; i++){
strArray[i] = textArray[i].getText().toString().trim(); //获得用户输入的信息数组

}
insert(strArray);

}

};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
textArray = new EditText[textIds.length];
for(int i=0;i<textIds.length;i++){
textArray[i] = (EditText)findViewById(textIds[i]);
}
myHelper = new MyOpenHelper(this, MyOpenHelper.DB_NAME, null, 1);
btn_save = (Button) findViewById(R.id.submit);
btn_save.setOnClickListener(myListener);

}
public void insert(String [] strArray)
{
SQLiteDatabase db = myHelper.getWritableDatabase(); //获得数据库对象
ContentValues values = new ContentValues();
values.put(NUMBER, strArray[0]);
values.put(NAME, strArray[1]);
long count = db.insert(TABLE_NAME, ID, values); //插入数据
db.close();
if(count == -1){
Toast.makeText(this, "插入失败!", Toast.LENGTH_SHORT).show();
}
else{
Toast.makeText(this, "插入成功!", Toast.LENGTH_SHORT).show();
}
}
}

删除记录的函数

删除记录的函数
 public void deleteContact(int id){
SQLiteDatabase db = myHelper.getWritableDatabase(); //获得数据库对象
db.delete(TABLE_NAME, ID+"=?", new String[]{id+""});
db.close();
}


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