sqlite数据库学习

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();
        }
    }
}