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Tham khảo tài liệu 'professional information technology-programming book part 116', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | MySQL is a popular open source database and MySQL ventures where no other databases have yet to venture by providing regular expression support as a way to perform database searches. Regular expression support in MySQL is accessed in WHERE clauses in the following format REGEXP expression Note A complete MySQL statement using a regular expression would use syntax like this SELECT FROM table WHERE REGEXP pattern . MySQL regular expression support is useful and powerful but it is not a full regular expression implementation Only search support is provided there is no support for replace operations. Searches are not case sensitive. To perform case-sensitive searches use the BINARY keyword between REGEXP and the expression itself . Use to match the start of a word and to match the end of a word. Lookaround is not supported. Embedded conditions are not supported. Octal character searching is not supported. a b e f and v are not supported. Backreferences are not supported. Perl Perl is the granddaddy of regular expression implementations and most other implementations attempt to be Perl compatible. Regular expression support is a core part of Perl and is used simply by specifying the operation and the pattern m pattern matches the specified pattern. s pattern pattern performs a replace operation. qr pattern returns a Regex obj ect that may be used later. split splits a string into substrings. Following are some useful notes pertaining to Perl regular expressions Modifiers may be passed after the pattern. Use i for searching that is not case sensitive and g for global match all matches . When you use backreferences returns everything before the matched string returns everything after the matched string returns the last matched subexpression and returns the entire matched string. PHP PHP provides Perl-compatible regular expression support via the PCRE package. Note As of PHP version 4.2.0 PRCE is automatically included and always available. Users of earlier versions of PHP
