Warehouse code address: https://gitee.com/liudegui/DatabaseLayer
overview
- When we need to use the MySQL database business, we sometimes want to quickly build an application. At this time, we can use temporary SQLite instead of MySQL for development; wait for the business to stabilize before switching to the MySQL database, which can also prevent multiple people from sharing a MySQL database. conflict.
- DatabaseLayer is a database package that supports Sqlite3 and MySQL, and supports cross-platform (Window and Linux). Refer to the database implementation in CppSQLite and POCO .
Features:
1. Provide a unified Sqlite3 and MySQL operation interface
2. Only simple packaging of Sqlite3 and MySQL API, the code is simple and easy to understand
3. CppSqlite3 does not use stl, and supports embedded platforms; CppMySQL uses a small amount of STL, Support cross-platform.
4. Does not support Unicode
5. For specific matters and methods, please refer to the examples in the demos
External header file DatabaseLayer.h
Enable MySQL or SQLite through C++ macro in DatabaseLayer.h. Of course, you can also use CppSQLite3.h or CppMySQL.h directly. The APIs of these two databases are as unified as possible.
/*!
\file DatabaseLayer.h
* \brief 数据库适配组件的基类
\remmarks 只定义了基本的函数，具体请查看各个子类
*/
#pragma once
#ifndef _CppDBLayer_H_
#define _CppDBLayer_H_
#define POCO_VERSION 0x01010001
#ifdef _SQLITE3_DB
class CppSQLite3Exception;
class CppSQLite3DB;
class CppSQLite3Query;
class CppSQLite3ResultSet;
class CppSQLite3Statement;
typedef CppSQLite3Exception CppDBException;
typedef CppSQLite3DB CppDB;
typedef CppSQLite3Query CppDBQuery;
typedef CppSQLite3ResultSet CppDBResultSet;
typedef CppSQLite3Statement CppDBStatement;
#endif
#ifdef _MySQL_DB
class CppMySQLException;
class CppMySQLDB;
class CppMySQLQuery;
class CppMySQLResultSet;
class CppMySQLStatement;
typedef CppMySQLException CppDBException;
typedef CppMySQLDB CppDB;
typedef CppMySQLQuery CppDBQuery;
typedef CppMySQLResultSet CppDBResultSet;
typedef CppMySQLStatement CppDBStatement;
#endif
/*!
\class DatabaseException
\brief 数据库异常处理基类
*/
class DatabaseException
{
public:
virtual const int errorCode() = 0;
virtual const char* errorMessage() = 0;
};
/*!
\class DatabaseLayer
\brief 数据库基本操作基类
*/
class DatabaseLayer
{
public:
virtual void open(const char* szFile) = 0;
virtual void close() = 0;
virtual bool tableExists(const char* szTable) = 0;
virtual int execDML(const char* szSQL) = 0;
virtual CppDBQuery execQuery(const char* szSQL) = 0;
virtual int execScalar(const char* szSQL, int nNullValue=0) = 0;
virtual void startTransaction() = 0;
virtual void commitTransaction() = 0;
virtual void rollback() = 0;
virtual bool isTransaction() = 0;
};
/*!
\class DatabaseQuery
\brief 数据库查询基类，不包含所有的数据
*/
class DatabaseQuery
{
public:
virtual int numFields() = 0;
virtual int fieldIndex(const char* szField) = 0;
virtual const char* fieldName(int nCol) = 0;
virtual int fieldDataType(int nCol) = 0;
virtual const char* fieldValue(int nField) = 0;
virtual const char* fieldValue(const char* szField) = 0;
virtual bool fieldDataIsNull(int nField) = 0;
virtual bool eof() = 0;
virtual void nextRow() = 0;
virtual void clear() = 0;
virtual int getIntField(int nField, int nNullValue = 0) = 0;
virtual int getIntField(const char* szField, int nNullValue = 0) = 0;
virtual double getDoubleField(int nField, double fNullValue = 0.0) = 0;
virtual double getDoubleField(const char* szField, double fNullValue = 0.0) = 0;
virtual const char* getStringField(int nField, const char* szNullValue = "") = 0;
virtual const char* getStringField(const char* szField, const char* szNullValue = "") = 0;
};
/*!
\class DatabaseResultSet
\brief 数据库查询结果集基类，包含所有的数据
*/
class DatabaseResultSet
{
public:
virtual int numFields() = 0;
virtual unsigned long numRows() = 0;
virtual int FieldColIndex(const char* szField) = 0;
virtual const char* fieldName(int nCol) = 0;
virtual const char* fieldValue(int nField) = 0;
virtual const char* fieldValue(const char* szField) = 0;
virtual bool fieldDataIsNull(int nField) = 0;
virtual bool eof() = 0;
virtual void nextRow() = 0;
virtual int seekRow(unsigned long nRow) = 0;
virtual void clear() = 0;
};
/*!
\class DatabaseStatement
\brief Statement基类
*/
class DatabaseStatement
{
public:
virtual int execDML() = 0;
virtual void bind(int nParam, const char* szValue) = 0;
virtual void bind(int nParam, const int nValue) = 0;
virtual void bind(int nParam, const double dwValue) = 0;
virtual void reset() = 0;
virtual void clear() = 0;
};
#if defined _SQLITE3_DB && !defined _CppSQLite3_H_
#include "CppSQLite3.h"
#endif
#if defined _MySQL_DB && !defined _CPPMYSQL_H_
#include "CppMySQL.h"
#endif
#ifdef _WIN32
#include "Platform_WIN32.h"
#endif
#endif
Example of use
The sample code demonstrates how to quickly switch data between SQLite and MySQL in business code
#include <stdlib.h>
#include <stdio.h>
#include <ctime>
#include <iostream>
#include "DatabaseLayer.h"
using namespace std;
#ifdef _SQLITE3_DB
const char* gszDB = "CppSQLite3Demo.db";
#endif
#ifdef _MySQL_DB
const char* gszDB = "CppMySQLDemo";
#endif
int main()
{
try
{
CppDB db;
int i, fld;
#ifdef _SQLITE3_DB
remove(gszDB);
#endif
#ifdef _MySQL_DB
db.connect("127.0.0.1", "root", "root");
db.dropDB(gszDB);
db.createDB(gszDB);
#endif
db.open(gszDB);
cout << endl << "emp table exists=" << (db.tableExists("emp") ? "TRUE":"FALSE") << endl;
cout << endl << "Creating emp table" << endl;
db.execDML("create table emp(empno int, empname char(20));");
cout << endl << "emp table exists=" << (db.tableExists("emp") ? "TRUE":"FALSE") << endl;
// 测试DML,打印影响行
cout << endl << "= 测试DML,打印影响行 =" << endl;
int nRows = db.execDML("insert into emp values (6, '勒布朗·詹姆斯');");
cout << nRows << " rows inserted" << endl;
nRows = db.execDML("update emp set empname = 'LeBron James' where empno = 6;");
cout << nRows << " rows updated" << endl;
nRows = db.execDML("delete from emp where empno = 7;");
cout << nRows << " rows deleted" << endl;
nRows = db.execDML("delete from emp where empno = 6;");
cout << nRows << " rows deleted" << endl;
// 测试事务和execScalar
cout << endl << "= 测试事务和execScalar =" << endl;
int nRowsToCreate(25000);
cout << endl << "Transaction test, creating " << nRowsToCreate;
cout << " rows please wait..." << endl;
db.startTransaction();
for (i = 0; i < nRowsToCreate; i++)
{
char buf[128];
sprintf(buf, "insert into emp values (%d, 'Empname%06d');", i, i);
db.execDML(buf);
}
db.commitTransaction();
cout << db.execScalar("select count(*) from emp;") << " rows in emp table";
// 重新创建表emp
cout << endl << "= 重新创建表emp = " << endl;
db.execDML("drop table emp;");
#ifdef _SQLITE3_DB
db.execDML("create table emp(empno integer primary key, empname char(20));");
#endif
#ifdef _MySQL_DB
db.execDML("CREATE TABLE emp(empno int not null auto_increment, empname char(20) not null, primary key (empno)) ENGINE=InnoDB;");
#endif
cout << nRows << " rows deleted" << endl;
for (i = 0; i < 5; i++)
{
char buf[128];
sprintf(buf, "insert into emp (empname) values ('帅锅%02d');", i+1);
db.execDML(buf);
}
// 测试CppDBQuery
cout << endl << "= 测试CppDBQuery =" << endl;
CppDBQuery q = db.execQuery("select * from emp order by 1;");
cout <<endl<<"Num of fields: "<< q.numFields() << endl;
#ifdef _SQLITE3_DB
cout <<endl<<"Num of rows: "<< db.execScalar("select count(*) from emp") << endl<<endl;
#endif
#ifdef _MySQL_DB
cout <<endl<<"Num of rows: "<< q.numRows() << endl<<endl;
#endif
for (fld = 0; fld < q.numFields(); fld++)
{
cout << q.fieldName(fld) << "|";
}
cout << endl;
while(!q.eof())
{
cout << q.getStringField(0) << "|";
cout << q.getStringField(1) << "|" << endl;
q.nextRow();
}
cout << endl << "= 赋值构造函数测试 =" << endl;
q = db.execQuery("select empname from emp;");
cout <<endl<<"Num of fields: "<< q.numFields() << endl;
q.clear();
// CppDBResultSet测试
cout << endl << "= CppDBResultSet测试 =" << endl;
CppDBResultSet t = db.getResultSet("select * from emp order by 1;");
cout <<endl<<"Num of fields: "<< t.numFields() << endl;
cout <<endl<<"Num of rows: "<< t.numRows() << endl << endl;
for (fld = 0; fld < t.numFields(); fld++)
{
cout << t.fieldName(fld) << "|";
}
cout << endl;
int row;
for (row = 0; row < (int)t.numRows(); row++)
{
t.seekRow(row);
for (fld = 0; fld < t.numFields(); fld++)
{
cout << t.fieldValue(fld) << "|";
}
cout << endl;
}
cout << endl << "另一种显示ResultSet的方法" << endl;
t.seekRow(0); //这步不可少
while (!t.eof())
{
cout << t.fieldValue(0) << "|";
cout << t.fieldValue(1) << "|";
cout << endl;
t.nextRow();
}
t.clear();
// 测试CppDBStatement
cout << endl << "= 测试CppDBStatement = " << endl;
cout << " rows please wait..." << endl;
db.execDML("drop table emp;");
db.execDML("create table emp(empno int, empname char(20));");
db.startTransaction();
nRowsToCreate = 200;
cout << endl << "Creating with bind by number" << endl;
CppDBStatement stmt = db.compileStatement("insert into emp values (?, ?);");
for (i = 0; i < nRowsToCreate; i++)
{
char buf[16];
sprintf(buf, "EmpName%02d", i);
stmt.bind(1, i);
stmt.bind(2, buf);
stmt.execDML();
stmt.reset();
}
stmt.clear();
db.commitTransaction();
cout << db.execScalar("select count(*) from emp;") << " rows in emp table " << endl;
t = db.getResultSet("select * from emp limit 10;");
for (fld = 0; fld < t.numFields(); fld++)
{
cout << t.fieldName(fld) << "|";
}
cout << endl;
for (row = 0; row < (int)t.numRows(); row++)
{
t.seekRow(row);
for (fld = 0; fld < t.numFields(); fld++)
{
cout << t.fieldValue(fld) << "|";
}
cout << endl;
}
cout << endl << "End of tests" << endl;
}
catch (CppDBException& e)
{
cerr <<endl<< "Exception:"<<e.errorCode() << ":" << e.errorMessage() << endl;
}
// Loop until user enters q or Q
char c(' ');
while (c != 'q' && c != 'Q')
{
cout << "Press q then enter to quit: ";
cin >> c;
}
return 0;
}