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sqlite数据库学习

2015-10-18 22:56 302 查看
1.0版代码:

package com.swust.sqlitedatabase.test;

import com.swust.sqlitedatabase.myOpenHelper;

import android.database.sqlite.SQLiteDatabase;
import android.test.AndroidTestCase;

public class TestCase extends AndroidTestCase {
public void test(){
//第一个参数:this->现在应用没启动,没有,真正的时候用this。所以获取虚拟上下文getContext()
//第二个参数:数据库文件
//第四个参数:版本号
//recNO字段是系统的,无视
myOpenHelper moh = new myOpenHelper(getContext(), "people.db", null, 1);
//如果数据库不存在,先创建数据库,再获取可读可写数据库对象,如果数据存在,就直接打开
SQLiteDatabase db=moh.getWritableDatabase();
//创建对象也可读可写,如果存储空间满了,那么返回只读数据库对象
//SQLiteDatabase db=moh.getReadableDatabase();
}
public void insert(){
myOpenHelper moh = new myOpenHelper(getContext(), "people.db", null, 1);
SQLiteDatabase db=moh.getWritableDatabase();
//数据库char ,double等都是字符串,因为这个轻量级数据不检测数据
db.execSQL("insert into person(name,salary,phone)values(?,?,?)",new Object[]{"王**","25.34",12.345});
db.execSQL("insert into person(name,salary,phone)values(?,?,?)",new Object[]{"王**大学",25.34,"12.345"});
db.execSQL("insert into person(name,salary,phone)values(?,?,?)",new Object[]{"王**","25.34",12.345});
db.execSQL("insert into person(name,salary,phone)values(?,?,?)",new Object[]{"王**大学",25.34,"12.345"});
db.close();
}
}


插入后:



删除:

public void delete(){
myOpenHelper moh = new myOpenHelper(getContext(), "people.db", null, 1);
SQLiteDatabase db=moh.getWritableDatabase();
db.execSQL("delete from person where name =?",new Object[]{"王**"});
}


之后,字段名字为“王**”的被删除

效果:



-------------------------------------

代码未优化:

package com.swust.sqlitedatabase.test;

import com.swust.sqlitedatabase.myOpenHelper;

import android.database.sqlite.SQLiteDatabase;
import android.test.AndroidTestCase;

public class TestCase extends AndroidTestCase {
public void test(){
//第一个参数:this->现在应用没启动,没有,真正的时候用this。所以获取虚拟上下文getContext()
//第二个参数:数据库文件
//第四个参数:版本号
//recNO字段是系统的,无视
myOpenHelper moh = new myOpenHelper(getContext(), "people.db", null, 1);
//如果数据库不存在,先创建数据库,再获取可读可写数据库对象,如果数据存在,就直接打开
SQLiteDatabase db=moh.getWritableDatabase();
//创建对象也可读可写,如果存储空间满了,那么返回只读数据库对象
//SQLiteDatabase db=moh.getReadableDatabase();
}
public void insert(){
myOpenHelper moh = new myOpenHelper(getContext(), "people.db", null, 1);
SQLiteDatabase db=moh.getWritableDatabase();
//数据库char ,double等都是字符串,因为这个轻量级数据不检测数据
db.execSQL("insert into person(name,salary,phone)values(?,?,?)",new Object[]{"王**","25.34",12.345});
db.execSQL("insert into person(name,salary,phone)values(?,?,?)",new Object[]{"王**大学",25.34,"12.345"});
db.execSQL("insert into person(name,salary,phone)values(?,?,?)",new Object[]{"王**","25.34",12.345});
db.execSQL("insert into person(name,salary,phone)values(?,?,?)",new Object[]{"王树青大学",25.34,"12.345"});
db.close();
}
public void delete(){ myOpenHelper moh = new myOpenHelper(getContext(), "people.db", null, 1); SQLiteDatabase db=moh.getWritableDatabase(); db.execSQL("delete from person where name =?",new Object[]{"王**"}); }
}


优化后:

package com.itheima.sqlitedatabase.test;

import com.itheima.sqlitedatabase.MyOpenHelper;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.test.AndroidTestCase;

public class TestCase extends AndroidTestCase {

//此时测试框架还没有初始化完毕,没有虚拟上下文对象
//    private MyOpenHelper oh = new MyOpenHelper(getContext(), "people.db", null, 1);
private MyOpenHelper oh;
private SQLiteDatabase db;
public void test(){
//getContext():获取一个虚拟的上下文
MyOpenHelper oh = new MyOpenHelper(getContext(), "people.db", null, 1);
//如果数据库不存在,先创建数据库,再获取可读可写的数据库对象,如果数据库存在,就直接打开
SQLiteDatabase db = oh.getWritableDatabase();
//如果存储空间满了,那么返回只读数据库对象
//        SQLiteDatabase db = oh.getReadableDatabase();
}

//测试框架初始化完毕之后,在测试方法执行之前,此方法调用
@Override
protected void setUp() throws Exception {
super.setUp();

oh = new MyOpenHelper(getContext(), "people.db", null, 1);
db = oh.getWritableDatabase();
}

//测试方法执行完毕之后,此方法调用
@Override
protected void tearDown() throws Exception {
// TODO Auto-generated method stub
super.tearDown();
db.close();
}

public void insert(){

//        db.execSQL("insert into person (name, salary, phone)values(?, ?, ?)", new Object[]{"小志的老婆[1]", "13000", 138438});
//        db.execSQL("insert into person (name, salary, phone)values(?, ?, ?)", new Object[]{"小志的儿子", 14000, "13888"});
db.execSQL("insert into person (name, salary, phone)values(?, ?, ?)", new Object[]{"小志", 14000, "13888"});
}

public void delete(){
db.execSQL("delete from person where name = ?", new Object[]{"小志"});
}

public void update(){
db.execSQL("update person set phone = ? where name = ?", new Object[]{186666, "小志的儿子"});
}

public void select(){
Cursor cursor = db.rawQuery("select name, salary from person", null);

while(cursor.moveToNext()){
//通过列索引获取列的值
String name = cursor.getString(cursor.getColumnIndex("name"));
String salary = cursor.getString(1);
System.out.println(name + ";" + salary);
}
}

public void insertApi(){
//把要插入的数据全部封装至ContentValues对象
ContentValues values = new ContentValues();
values.put("name", "游天龙");
values.put("phone", "15999");
values.put("salary", 16000);
db.insert("person", null, values);
}

public void deleteApi(){
int i = db.delete("person", "name = ? and _id = ?", new String[]{"小志的儿子", "3"});
System.out.println(i);
}

public void updateApi(){
ContentValues values = new ContentValues();
values.put("salary", 26000);
int i = db.update("person", values, "name = ?", new String[]{"游天龙"});
System.out.println(i);
}

public void selectApi(){
Cursor cursor = db.query("person", null, null, null, null, null, null, null);
while(cursor.moveToNext()){
String name = cursor.getString(cursor.getColumnIndex("name"));
String phone = cursor.getString(cursor.getColumnIndex("phone"));
String salary = cursor.getString(cursor.getColumnIndex("salary"));
System.out.println(name + ";" + phone + ";" + salary);
}
}

public void transaction(){
try{
//开启事务
db.beginTransaction();
ContentValues values = new ContentValues();
values.put("salary", 12000);
db.update("person", values, "name = ?", new String[]{"小志"});

values.clear();
values.put("salary", 16000);
db.update("person", values, "name = ?", new String[]{"小志的儿子"});

int i = 3/0;
//设置  事务执行成功
db.setTransactionSuccessful();
}
finally{
//关闭事务,同时提交,如果已经设置事务执行成功,那么sql语句就生效了,反之,sql语句回滚
db.endTransaction();
}
}
}
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