Question

Altough SQLite支持关系数据库，我不确定这是在Poco库中实现的。来自 poco-1.6.0-all / Data / SQLite / testsuite / src / SQLiteTest.cpp 的单元测试似乎没有一个例子，我无法找到任何地方明确确认这是可能的。

在http://pocoproject.org/docs/00200-DataUserManual.html的示例中，名称后面有一个简单的选择：

std::string aName;
std::string match("Peter");
ses << "SELECT name FROM names WHERE name=?", into(aName), use(match), now;

让我们说，我希望看到彼得公司的工作，从包含公司描述的不同表格，给出公司ID：

// Untested
std::string aName;
std::string aCompany;
std::string match("Peter");
ses << "SELECT name, company_name FROM names, companies WHERE name=? AND company_id=2", 
    into(aName), into(aCompany), use(match), now;

我该怎么做？

Answer 1

这是一个SQL问题;以下是如何使用POCO：

Session tmp (Poco::Data::SQLite::Connector::KEY, "dummy.db");

tmp << "DROP TABLE IF EXISTS Simpsons", now;
tmp << "DROP TABLE IF EXISTS Companies", now;
tmp << "CREATE TABLE IF NOT EXISTS Simpsons (LastName VARCHAR, FirstName VARCHAR)", now;
tmp << "CREATE TABLE IF NOT EXISTS Companies (CompanyName VARCHAR, LastName VARCHAR, FirstName VARCHAR)", now;

tmp << "INSERT INTO Simpsons VALUES(?, ?)", bind("Simpson"), bind("Bart"), now;
tmp << "INSERT INTO Simpsons VALUES(?, ?)", bind("Simpson"), bind("Homer"), now;

tmp << "INSERT INTO Companies VALUES(?, ?, ?)", bind("Microsoft"), bind("Simpson"), bind("Bart"), now;
tmp << "INSERT INTO Companies VALUES(?, ?, ?)", bind("Oracle"), bind("Simpson"), bind("Homer"), now;

std::string fname, lname, cname;
tmp << "SELECT P.FirstName, P.LastName, C.CompanyName "
        "FROM Simpsons P, Companies C "
        "WHERE P.FirstName = ? AND P.FirstName = C.FirstName", bind("Bart"), into(fname), into(lname), into(cname), now;

std::cout << lname << ',' << fname << " works for " << std::endl;

输出：

辛普森，巴特为微软工作

在Poco SQLite中的表之间加入

1 个答案: