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DarkSide SQL Mini Version 1, The embedded database

, 23 Mar 2006
An embedded database library in C++.
/**
Copyright 2000 - 2003 LogicMatrix. All rights reserved. 

This software is distributed under the LogicMatrix Free Software License. This software may be used for any purpose, personal or commercial. Redistributions in binary /source code form are permitted. Commercial redistribution of larger works derived from, or works which bundle this software requires a "Commercial Redistribution License" which can be purchased from LogicMatrix. Contact LogicMatrix for details

Redistributions qualify as Free and non-commercial under one of the following terms:

1) Redistributions are made at no charge beyond the reasonable cost of materials and delivery.
2) Redistributions in binary/source code form must reproduce this Copyright Notice,these license terms, and the disclaimer/limitation of liability set forth as below, in the documentation and/or other materials
provided with the distribution.

Disclaimer
==========
The Software is provided on an "AS IS" basis. No warranty is
provided that the Software is free of defects, or fit for a
particular purpose. 

Limitation of Liability 
=======================
LogicMatrix shall not be liable for any damages suffered by the Licensee or any third party resulting from use of the Software.


**/

/**
	delete.cpp

  Purpose: Handles DELETE command
  
	Author: Vijay Mathew Pandyalakal
	Date:	17/11/2003
	Copyright: logicmatrix
**/

#include <string>
#include <vector>
using namespace std;

#include "db_cxx.h"

#include "mydate.h"
using namespace openutils;

#include "dsql_m_structs.h"
#include "bridge.h"
#include "sql_utils.h"
#include "cmpr.h"
#include "sql_lexer.h"
#include "bdb_index.h"
#include "rec.h"
#include "delete.h"
using namespace dsqlm;

Delete::Delete(const char* sql,Database *db) {
	this->sql = sql;
	if(db == 0) {
		throw DsqlMException("Delete.cpp - database not inited");
	}
	m_db = db;
}

long Delete::parse() {
	SQLLexer lexer(sql.c_str());
	vector<string> vct = lexer.tokenize();
	int tsz = vct.size();
	if(tsz < 3) {
		throw DsqlMException("Not a valid DELETE statement");
	}
	string s = vct[0];
	if(strcmpi(s.c_str(),"DELETE") != 0) {
		throw DsqlMException("Not a valid DELETE statement");
	}
	s = vct[1];
	if(strcmpi(s.c_str(),"FROM") != 0) {
		throw DsqlMException("FROM keyword not found where expected");
	}
	s = vct[2];
	Table table(s.c_str(),m_db);
	table.open();
	Rec rec(&table,m_db);
	if(tsz == 3) { // no "where" clause
		char filnm[101];
		sprintf(filnm,"%s\\%s_data",m_db->getDBName().c_str(),
			table.getName().c_str());
		long filsz = rec.fileLength();
		int reclen = rec.recLength();		
		unlink(filnm);
		int cols = table.getNumberOfColumns();
		for(int i=0;i<cols;i++) {
			Column col = table.getCol(i+1);
			if(col.isIndexed() == TRUE || col.isUnique() == TRUE) {
				sprintf(filnm,"%s\\%s_%s_x",m_db->getDBName().c_str(),
					table.getName().c_str(),
					col.getTitle().c_str());
				unlink(filnm);
			}
			if(col.getType() == AUTOID) {
				sprintf(filnm,"%s\\%s_%s_aid",m_db->getDBName().c_str(),
					table.getName().c_str(),
					col.getTitle().c_str());
				unlink(filnm);
			}
		}		
		return (long)(filsz/reclen);
	}else { // has a WHERE clause
		s = vct[3];
		if(strcmpi(s.c_str(),"WHERE") != 0) {
			throw DsqlMException("Expected WHERE caluse not found");
		}else if(tsz < 7) {
			throw DsqlMException("Invalid WHERE condition");
		}
		int idx = 4;
		vector<long> vct_pos;
		/**
		Copied from select.cpp
		**/		
		TokenType tt = ID;		
		vector<Column> vct_cols;
		vector<ComparissonOperator> vct_coprs; 
		vector<string> vct_vals;
		vector<LogicalOperator> vct_loprs;
		SQLUtils utils(m_db);
		for(int i=idx;i<tsz;i++) {
			s = vct[i];
			if(tt == ID) {
				Column col = table.getCol(s.c_str());
				tt = COPR;
				vct_cols.push_back(col);
			}else if(tt == COPR) {
				vct_coprs.push_back(utils.createComparissonOperator(s.c_str()));
				tt = ANY;
			}else if(tt == ANY) {
				vct_vals.push_back(s);
				tt = LOPR;
			}else if(tt == LOPR) {
				vct_loprs.push_back(utils.createLogicalOperator(s.c_str()));
				tt = ID;
			}else {
				char err_buff[50];
				sprintf(err_buff,"Unexpected token at %d",(i+1));
			}
		}
		Cmpr cmpr(&table,m_db,vct_cols,vct_coprs,vct_vals,vct_loprs);
		cmpr.run();
		long csz = cmpr.getCursorLength();
		for(long k=0;k<csz;k++) {
			vct_pos.push_back(cmpr.getPos(k));
		}
		/**
		**/

		// actual deletion
		long ret = 0;
		for(long h=0;h<vct_pos.size();h++) {
			long pos = vct_pos[h];
			rec.read(pos);
			if(!rec.isDeleted()) {
				rec.del();
				for(int c=0;c<table.getNumberOfColumns();c++) {
					Column col = table.getCol((c+1));
					if(col.isIndexed() == TRUE || col.isUnique() == TRUE) {
						bool uk = false;
						/*if(col.isUnique() == TRUE) {
							uk = true;
						}*/
						char fil[101];
						sprintf(fil,"%s\\%s_%s_x",m_db->getDBName().c_str(),
							table.getName().c_str(),
							col.getTitle().c_str());
						BdbIndex index(fil,uk);
						char data[24];
						sprintf(data,"%d",pos);
						index.del(rec.getField((c+1)).c_str(),data);
					}
				}
				rec.write(pos);
				ret++;
			}
		}
		return ret;
	}
}

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