SQL Logic Error Detection by Using Start End Mid Algorithm

Data base is an important part of a system and it stores data to be manipulated. A language called SQL (Structured Query Language) is used for manipulating those data to make needed information. There are two types of error which make SQL more difficult in practical implementation. They are syntax error and logic error. The difference between them is that syntax error can be detected by compiler so it is easy to learn by its warning. But compiler does not show error warning if logical error was occurred. It makes logic error is more difficult to understand than syntax error. To help data base's user to learn SQL in practical implementation, web based SQL compiler that be able to detect syntax and logic error is developed by using Start End Mid algorithm

Efficient Online Timed Pattern Matching by Automata-Based Skipping

The timed pattern matching problem is an actively studied topic because of its relevance in monitoring of real-time systems. There one is given a log $w$ and a specification $\mathcal{A}$ (given by a timed word and a timed automaton in this paper), and one wishes to return the set of intervals for which the log $w$, when restricted to the interval, satisfies the specification $\mathcal{A}$. In our previous work we presented an efficient timed pattern matching algorithm: it adopts a skipping mechanism inspired by the classic Boyer--Moore (BM) string matching algorithm. In this work we tackle the problem of online timed pattern matching, towards embedded applications where it is vital to process a vast amount of incoming data in a timely manner. Specifically, we start with the Franek-Jennings-Smyth (FJS) string matching algorithm---a recent variant of the BM algorithm---and extend it to timed pattern matching. Our experiments indicate the efficiency of our FJS-type algorithm in online and offline timed pattern matching

Optimising Unicode Regular Expression Evaluation with Previews

The jsre regular expression library was designed to provide fast matching of complex expressions over large input streams using user-selectable character encodings. An established design approach was used: a simulated non-deterministic automaton (NFA) implemented as a virtual machine, avoiding exponential cost functions in either space or time. A deterministic automaton (DFA) was chosen as a general dispatching mechanism for Unicode character classes and this also provided the opportunity to use compact DFAs in various optimization strategies. The result was the development of a regular expression Preview which provides a summary of all the matches possible from a given point in a regular expression in a form that can be implemented as a compact DFA and can be used to further improve the performance of the standard NFA simulation algorithm. This paper formally defines a preview and describes and evaluates several optimizations using this construct. They provide significant speed improvements accrued from fast scanning of anchor positions, avoiding retesting of repeated strings in unanchored searches, and efficient searching of multiple alternate expressions which in the case of keyword searching has a time complexity which is logarithmic in the number of words to be searched

A Boyer-Moore-style algorithm for regular expression pattern matching

AbstractThis paper presents a Boyer–Moore-type algorithm for regular expression pattern matching, answering an open problem posed by Aho in 1980 (Pattern Matching in Strings, Academic Press, New York, 1980, p. 342). The new algorithm handles patterns specified by regular expressions—a generalization of the Boyer–Moore and Commentz-Walter algorithms.Like the Boyer–Moore and Commentz-Walter algorithms, the new algorithm makes use of shift functions which can be precomputed and tabulated. The precomputation algorithms are derived, and it is shown that the required shift functions can be precomputed from Commentz-Walter's d1 and d2 shift functions.In certain cases, the Boyer–Moore (respectively Commentz-Walter) algorithm has greatly outperformed the Knuth–Morris–Pratt (respectively Aho–Corasick) algorithm (as discussed by Watson in his Ph.D. Thesis, Eindhoven University of Technology, September 1995, and in: N. Ziviani, R. Baeza-Yates, K. Guimaraes (Eds.), Proc. Third South American Workshop on String Processing, International Informatics Series, vol. 4, Carleton University Press, Recife, Brazil, 1996, pp. 280–294). In testing, the algorithm presented in this paper also frequently outperforms the regular expression generalization of the Aho–Corasick algorithm