一直以来，笔者都在不停寻找一种更人性化的数据库访问方式（并不是说默认的方式不好，而是有时候的确在模块化设计中不太方便）。
后来有幸在php中找到codeigniter的ActiveReord，详细参考这篇文章: 抽离CodeIgniter的数据库访问类！
然而c++却始终用着最原始的方式，昨天趁着项目要用的机会，在网上搜索了好久，总算让我找到两套c++的数据库访问框架:
soci
litesql
两套代码我都拿下来看了一下，litesql实现了一套完整的代码自动生成，功能强大，但是也很重；soci相对要轻量，但是同样也实现了数据结构到数据库表的映射。本人还是比较喜欢轻量的东西，所以最终选择了soci。经过这两天的试用，感觉非常不错。
官方的文档也很详细，所以这里就用我写的单元测试代码来做一下简单的讲解:
首先创建库表:
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| 1234567891011121314151617 | create database soci;CREATE TABLE `tb_test` ( `id` int(11) NOT NULL auto_increment, `name` varchar(32) default "", `sex` int(11) default 0, PRIMARY KEY (`id`), UNIQUE KEY `name` (`name`)); create database soci;CREATE TABLE `tb_test` ( `id` int(11) NOT NULL auto_increment, `name` varchar(32) default "", `sex` int(11) default 0, PRIMARY KEY (`id`), UNIQUE KEY `name` (`name`)); |
1.简单的select单条记录
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| 123456789101112131415161718192021222324252627282930313233343536373839 | TEST(soci,select_one){ try { session sql(mysql, "host=localhost db=soci user=dantezhu"); indicator ind; string name = "dandan"; int sex; sql << "select sex from tb_test where name = :name", into(sex, ind), use(name); ASSERT_EQ(ind, i_ok) << name; } catch (exception const &e) { FAIL()<<e.what(); }} TEST(soci,select_one){ try { session sql(mysql, "host=localhost db=soci user=dantezhu"); indicator ind; string name = "dandan"; int sex; sql << "select sex from tb_test where name = :name", into(sex, ind), use(name); ASSERT_EQ(ind, i_ok) << name; } catch (exception const &e) { FAIL()<<e.what(); }} |
select的结果，如果成功则ind会为i_ok，同值sex被赋值；如果失败则反之
2.简单的select多条记录
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| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657 | TEST(soci,select_multi2){ try { session sql(mysql, "db=soci user=dantezhu"); indicator ind; int count; sql << "select count(*) from tb_test", into(count, ind); ASSERT_EQ(ind, i_ok) << count; if (count == 0) { SUCCEED(); return; } int sex = 1; vector<string> vec_name(count); vector<int> vec_sex(count); sql << "select name,sex from tb_test where sex = :sex", into(vec_name), into(vec_sex), use(sex); } catch (exception const &e) { FAIL()<<e.what(); }} TEST(soci,select_multi2){ try { session sql(mysql, "db=soci user=dantezhu"); indicator ind; int count; sql << "select count(*) from tb_test", into(count, ind); ASSERT_EQ(ind, i_ok) << count; if (count == 0) { SUCCEED(); return; } int sex = 1; vector<string> vec_name(count); vector<int> vec_sex(count); sql << "select name,sex from tb_test where sex = :sex", into(vec_name), into(vec_sex), use(sex); } catch (exception const &e) { FAIL()<<e.what(); }} |
与select单条记录唯一的区别即，into()的参数是一个vector。其实用多个vector这种方式并不是一个很好的选择，后面会介绍基于数据结构的方式。
3.简单的insert
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| 1234567891011121314151617181920212223242526272829303132333435 | TEST(soci,insert_exist){ try { session sql(mysql, "db=soci user=dantezhu"); string name = "dandan"; int sex = 1; sql << "insert into tb_test(name, sex) values(:name, :sex)", use(name), use(sex); } catch (exception const &e) { SUCCEED()<<e.what(); }} TEST(soci,insert_exist){ try { session sql(mysql, "db=soci user=dantezhu"); string name = "dandan"; int sex = 1; sql << "insert into tb_test(name, sex) values(:name, :sex)", use(name), use(sex); } catch (exception const &e) { SUCCEED()<<e.what(); }} |
insert，update，delete都有两个同样的问题:
a)affect_rows(操作的行数)没有办法返回
b)操作的id无法知道，尤其对于insert的主键是自增的情况下，无法知道插入的主键的值是多少。
update和delete都与insert相似，这里就不再多说。
接下来是这个框架的很重要的一个特性，即数据库表与数据结构绑定：
首先我们需要定义一个结构体，并告知soci怎么让列名和数据结构的字段对应起来:
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| 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455 | struct Person{ int id; std::string name; int sex;}; namespace soci{ template<> struct type_conversion<Person> { typedef values base_type; static void from_base(values const & v, indicator /* ind */, Person & p) { p.id = v.get<int>("id"); p.name = v.get<std::string>("name"); p.sex = v.get<int>("sex"); } static void to_base(const Person & p, values & v, indicator & ind) { v.set("id", p.id); v.set("name", p.name); v.set("sex", p.sex); ind = i_ok; } };} struct Person{ int id; std::string name; int sex;}; namespace soci{ template<> struct type_conversion<Person> { typedef values base_type; static void from_base(values const & v, indicator /* ind */, Person & p) { p.id = v.get<int>("id"); p.name = v.get<std::string>("name"); p.sex = v.get<int>("sex"); } static void to_base(const Person & p, values & v, indicator & ind) { v.set("id", p.id); v.set("name", p.name); v.set("sex", p.sex); ind = i_ok; } };} |
关于
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| 123 | template<> struct type_conversion<Person> template<> struct type_conversion<Person> |
这里，官方的文档是是有误的，我查了好长时间，按照上面的写法来写即可。
1.用数据结构来select
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| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869 | TEST(soci,select_obj_one){ try { session sql(mysql, "db=soci user=dantezhu"); indicator ind; int count; sql << "select count(*) from tb_test", into(count, ind); ASSERT_EQ(ind, i_ok) << count; string name = "dandan"; Person p; sql << "select id,name,sex from tb_test where name = :name", into(p, ind), use(name); ASSERT_EQ(ind, i_ok) << name; if (sql.got_data()) { cout<< p.id << "," << p.name << "," << p.sex << endl; } } catch (exception const &e) { FAIL()<<e.what(); }} TEST(soci,select_obj_one){ try { session sql(mysql, "db=soci user=dantezhu"); indicator ind; int count; sql << "select count(*) from tb_test", into(count, ind); ASSERT_EQ(ind, i_ok) << count; string name = "dandan"; Person p; sql << "select id,name,sex from tb_test where name = :name", into(p, ind), use(name); ASSERT_EQ(ind, i_ok) << name; if (sql.got_data()) { cout<< p.id << "," << p.name << "," << p.sex << endl; } } catch (exception const &e) { FAIL()<<e.what(); }} |
2.用数据结构来进行insert
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| 1234567891011121314151617181920212223242526272829303132333435363738394041 | TEST(soci,insert_obj_noexist){ try { session sql(mysql, "db=soci user=dantezhu"); Person p = { 0, "niuniu", 2 }; sql << "insert into tb_test(name, sex) values(:name, :sex)", use(p); } catch (exception const &e) { FAIL()<<e.what(); }} TEST(soci,insert_obj_noexist){ try { session sql(mysql, "db=soci user=dantezhu"); Person p = { 0, "niuniu", 2 }; sql << "insert into tb_test(name, sex) values(:name, :sex)", use(p); } catch (exception const &e) { FAIL()<<e.what(); }} |
整个就是这样~~下面是文中代码文件的下载路径：
http://code.google.com/p/vimercode/source/browse/#svn%2Ftrunk%2Fsoci_test
另外，虽然python下的mysql访问也算比较简单，但还是想知道是否有更Pythonic的库或接口，如果有朋友知道，欢迎不吝告知。
随时随地看视频
