For speed, Thompson implemented regular expression matching by just-in-time compilation (JIT) to IBM 7094 code on the Compatible Time-Sharing System, an important early example of JIT compilation. Among the first appearances of regular expressions in program form was when Ken Thompson built Kleene's notation into the editor QED as a means to match patterns in text files. Regular expressions entered popular use from 1968 in two uses: pattern matching in a text editor and lexical analysis in a compiler. Other early implementations of pattern matching include the SNOBOL language, which did not use regular expressions, but instead its own pattern matching constructs. These arose in theoretical computer science, in the subfields of automata theory (models of computation) and the description and classification of formal languages. Regular expressions originated in 1951, when mathematician Stephen Cole Kleene described regular languages using his mathematical notation called regular events. History Stephen Cole Kleene, who introduced the concept Regular expressions are supported in many programming languages. Regular expressions are used in search engines, in search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK, and in lexical analysis. Different syntaxes for writing regular expressions have existed since the 1980s, one being the POSIX standard and another, widely used, being the Perl syntax. They came into common use with Unix text-processing utilities. The concept of regular expressions began in the 1950s, when the American mathematician Stephen Cole Kleene formalized the concept of a regular language. Regular expression techniques are developed in theoretical computer science and formal language theory. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation. Int noOfRowDeleted = highlights show the match results of the regular expression pattern: /h+/ g (the letter h followed by one or more vowels)Ī regular expression (shortened as regex or regexp sometimes referred to as rational expression ) is a sequence of characters that specifies a match pattern in text. Int noOfRowInserted = ( "insert into student(studentname) Set studentname ='changed student by command' where studentid=1") using ( var ctx = new SchoolDBEntities()) The Database.ExecuteSqlCommnad() method is useful in executing database commands, such as the Insert, Update and Delete command. or string studentName = ( "Select studentname from Student where new 1)) Get student name of string type string studentName = ( "Select studentname from Student where studentid=1") The Database.SqlQuery() method returns a value of any type. The Database class represents the underlying database and provides various methods to deal with the database. this will throw an exception var studentName = ( "Select * from Courses").ToList() Using ( var ctx = new SchoolDBEntities()) DbSet.SqlQuery() only returns the result from the corresponding Students table and not from any other table). The DbSet.SqlQuery() executes the SQL query only for the table which is mapped with the specified entity (e.g. this will throw an exception var studentName = ( "Select studentid as id, studentname as nameįrom Student where studentname='Steve'").ToList() The following example will throw an exception. If you change the column name in SQL query, then it will throw an exception because it must match column names. SqlQuery( "Select * from Students where new 1)) You can specify the parameters using the object of SqlParameter, as shown below. The column names in the SQL query must match with the properties of an entity type, otherwise, it will throw an exception. The above query executes Select * from Students SQL in the database to get all students and will be converted into a list of Student entities. ![]() The resulted entities will be tracked by the context, as if they were returned by the LINQ query. ![]() Use the DbSet.SqlQuery() method to write raw SQL queries which return entity instances. The following methods can be used to execute raw SQL queries to the database using Entity Framework 6.x: Next Execute Raw SQL Queries in Entity Framework 6Įntity Framework allows you to execute raw SQL queries for the underlying relational database.
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