minisql.cpp

实现一个精简型单用户SQL引擎(DBMS)MiniSQL

#include "MiniSQL.h"

extern _M_Buffer Buffer;
extern unsigned int BTreeNodeSize;
extern char* ErrorMessage[];
extern char CurLocation[256];
extern char CurRelationName[33];
extern unsigned int  SizeOfPageHead;

void Init_MiniSQL();
void Run_MiniSQL();
void Exit_MiniSQL();

int main()
{
  Init_MiniSQL();   //初始化一些基本配置
  Run_MiniSQL();    //交互操作，是本程序的主体
  Exit_MiniSQL();   //善后操作，在退出
  return 1; 
}

void Init_MiniSQL()
{
  std::cout<<"                         WELCOME TO USE OUR MINISQL!";
  Buffer.Start();  // initialize the buffer
}

void Exit_MiniSQL()
{
  Buffer.End();    // close the buffer
  return;
}

void Run_MiniSQL()
{
  MSG msg = DEFAULT;  // make msg != QUIT  

  while(QUIT != msg)  // quit the program
  { 
    try
    { 
      TB_Create_Info* pCreateInfo;
      TB_Select_Info* pSelectInfo;
      TB_Insert_Info* pInsertInfo;
      TB_Update_Info* pUpdateInfo;
      TB_Delete_Info* pDeleteInfo;
      // get commmand from API and execute according operation
      msg = GetCommand(&pCreateInfo,&pSelectInfo,
                       &pInsertInfo,&pUpdateInfo,&pDeleteInfo);
      
      switch(msg)
      {
        case CREATE :  Create( *pCreateInfo );   break;
        case SELECT :  Select( *pSelectInfo );   break;
        case INSERT :  Insert( *pInsertInfo );   break;
        case UPDATE :  Update( *pUpdateInfo );   break;
        case DELETE :  Delete( *pDeleteInfo );   break;
        case DROP   :  Ctrl_DropTB();            break;
        case DROPDB :  Ctrl_DropDB();            break;
        case QUIT   :  break;
        default     :  break;
      }
    }
        
      catch (int ERROR_CODE)
      { 
        //print the error message
        DispatchError(ERROR_CODE);  
      }

  }
 	return;
}