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《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,std::forward_as_tuple(1,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,?)"; 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,city)); */ ret = db.addBindValue(i,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,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] = {" "}; 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,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,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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