A SQLite client library written in Modern C++

《A SQLite client library written in Modern C++》要点：
本文介绍了A SQLite client library written in Modern C++，希望对您有用。如果有疑问，可以联系我们。

smartdb是一个纯c++11开发,header-only,简练高效的sqlite封装库.

• 连接数据库,若test.db不存在,则会创立一个.

• INSERT操作.

  std::string sql = "INSERT INTO PersonTable(id, name, address) VALUES(?, ?, ?)"; db.execute(sql, 1, "Jack", nullptr);

  或者可以如许写：

  std::string sql = "INSERT INTO PersonTable(id, name, address) VALUES(?, ?, ?)"; db.execute(sql, std::forward_as_tuple(1, "Jack", nullptr));

  正如你所看到的,execute支持变参和std::tuple作为变量替换SQL里面的?,其中nullptr可以将数据库字段设置成null值,若要进行批量插入,建议使用事务和prepare进行处置,具体操作请看Example.

• SELECT操作

  db.execute("SELECT * FROM PersonTable"); while (!db.isEnd) { std::cout << "id: " << db.getFiled<sqlite3_int64>(0) << std::endl; std::cout << "name: " << db.getFiled<std::string>(1) << std::endl; std::cout << "address: " << db.getFiled<std::string>(2) << std::endl; db.moveNext; }

  使用isEnd和moveNext即可遍历结果集,获取字段值必要提供字段的类型以及字段序号,没有使用字段名来代替字段序号来获取值,主要是考虑到效率问题.

• 使用聚合函数

  db.execute("SELECT COUNT(*) FROM PersonTable"); if (db.recordCount == 1 && !db.isEnd) { std::cout << db.getFiled<sqlite3_int64>(0) << std::endl; }

Example

#include <iostream>#include <fstream>#include "Timer.hpp"#include "smartdb/Database.hpp"void testInsertTable{    smartdb::Database db;    bool ok = db.open("test.db");    std::string sql = "DROP TABLE PersonTable";    ok = db.execute(sql);    sql = "CREATE TABLE if not exists PersonTable(id INTEGER NOT NULL, name Text, address Text)";    ok = db.execute(sql);    Timer t;    sql = "INSERT INTO PersonTable(id, name, address) VALUES(?, ?, ?)";    const char* name = "Jack";    std::string city = "Chengdu";    // 预处置sql.    ok = db.prepare(sql);    // 开始事务.    ok = db.begin;    bool ret = true;    for (int i = 1; i < 1000000; ++i)    {        // 绑定参数.        /* ret = db.addBindValue(std::forward_as_tuple(i, name, city)); */        ret = db.addBindValue(i, name, city);        if (!ret)        { std::cout << "Error message: " << db.getErrorMessage << std::endl; break;        }    }    if (ret)    {        // 提交事务.        ok = db.commit;    }    else    {        // 回滚事务.        ok = db.rollback;    }    // 100w 800~1000ms.    std::cout << "Insert elapsed: " << t.elapsed << std::endl;    t.reset;    // select.    ok = db.execute("SELECT * FROM PersonTable");    std::cout << "Record count: " << db.recordCount << std::endl;    while (!db.isEnd)    {        db.moveNext;    }    // 100w 300~500ms.    std::cout << "Select elapsed: " << t.elapsed << std::endl;    (void)ok;}void testInsertTable2{    smartdb::Database db;    bool ok = db.open("test.db");    std::string sql = "DROP TABLE PersonTable2";    ok = db.execute(sql);    sql = "CREATE TABLE if not exists PersonTable2(id INTEGER NOT NULL, name Text, address Text, headerImage BLOB)";    ok = db.execute(sql);    // 读取一张图片.    std::ifstream fin;    fin.open("./1.jpg", std::ios::binary);    ok = fin.is_open;    char buf[50 * 1025] = {"\0"};    fin.read(buf, sizeof(buf));    std::string image = std::string(buf, fin.gcount);    smartdb::Blob headImage;    headImage.buf = image.c_str;    headImage.size = image.length;    sql = "INSERT INTO PersonTable2(id, name, address, headerImage) VALUES(?, ?, ?, ?)";    for (int i = 0; i < 10; ++i)    {        /* ok = db.execute(sql, i, "Tom", nullptr, headImage); */        ok = db.execute(sql, std::forward_as_tuple(i, "Tom", nullptr, headImage));    }    // update.    sql = "UPDATE PersonTable2 SET address=? WHERE id=?";    if (!db.execute(sql, "中国", 0))    {        std::cout << "Error message: " << db.getErrorMessage << std::endl;        return;    }    std::cout << "Update success, affected rows: " << db.affectedRows << std::endl;    // select.    ok = db.execute("SELECT * FROM PersonTable2 WHERE id=?", 0);    /* ok = db.execute("SELECT * FROM PersonTable2"); */    while (!db.isEnd)    {        try        { std::cout << "id: " << db.getFiled<sqlite3_int64>(0) << std::endl; std::cout << "name: " << db.getFiled<std::string>(1) << std::endl; std::cout << "address: " << db.getFiled<std::string>(2) << std::endl; std::cout << "image size: " << db.getFiled<std::string>(3).size << std::endl;        }        catch (std::exception& e)        { std::cout << "Exception: " << e.what << std::endl; return;        }        db.moveNext;    }    ok = db.execute("SELECT COUNT(*) FROM PersonTable2");    if (db.recordCount == 1 && !db.isEnd)    {        std::cout << "COUNT(*): " << db.getFiled<sqlite3_int64>(0) << std::endl;    }    (void)ok;}int main{    testInsertTable;    testInsertTable2;    return 0;}

依附性

兼容性

• Linux x86_64gcc 4.8, gcc4.9, gcc 5.
• Windows x86_64Visual Studio 2015

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