编写SQL语句操作数据库

代码：

package com.example.sqlitedemo;

import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SQLiteDatabase db=openOrCreateDatabase("user.db",MODE_PRIVATE,null);
db.execSQL("create table if not exists usertb(_id integer primary key autoincrement,name text not null,sex text not null,age integer not null)");
db.execSQL("insert into usertb(name,sex,age) values('张三','男',18)");
db.execSQL("insert into usertb(name,sex,age) values('李四','男',19)");
db.execSQL("insert into usertb(name,sex,age) values('小丽','女',18)");
Cursor cursor=db.rawQuery("select * from usertb",null);
if(cursor!=null){
while(cursor.moveToNext()){
Log.i("名字","姓名:"+cursor.getString(1));
}
cursor.close();
}
db.close();

}

}