android之sqlite数据库初级

赵小黑

package com.example.testsqlite;

import android.os.Bundle;
import android.app.Activity;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
import android.view.Menu;
import android.widget.Toast;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

//打开或创建test.db数据库
SQLiteDatabase db = openOrCreateDatabase("test.db", Context.MODE_PRIVATE, null);
db.execSQL("DROP TABLE IF EXISTS person");
//创建person表
db.execSQL("CREATE TABLE person (_id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR, age SMALLINT)");
Person person = new Person();
person.name = "john";
person.age = 30;
//插入数据
db.execSQL("INSERT INTO person VALUES (NULL, ?, ?)", new Object[]{person.name, person.age});

person.name = "david";
person.age = 33;
//ContentValues以键值对的形式存放数据
ContentValues cv = new ContentValues();
cv.put("name", person.name);
cv.put("age", person.age);
//插入ContentValues中的数据
db.insert("person", null, cv);

cv = new ContentValues();
cv.put("age", 35);
//更新数据
db.update("person", cv, "name = ?", new String[]{"john"});

Cursor c = db.rawQuery("SELECT * FROM person WHERE age >= ?", new String[]{"33"});
while (c.moveToNext()) {
int _id = c.getInt(c.getColumnIndex("_id"));
String name = c.getString(c.getColumnIndex("name"));
int age = c.getInt(c.getColumnIndex("age"));
Toast.makeText(this, "_id=>" + _id + ", name=>" + name + ", age=>" + age , Toast.LENGTH_SHORT );
Log.i("db", "_id=>" + _id + ", name=>" + name + ", age=>" + age);
}
c.close();

//删除数据
db.delete("person", "age < ?", new String[]{"35"});

//关闭当前数据库
db.close();

//删除test.db数据库
//deleteDatabase("test.db");



}

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

}