Detailed explanation of the use of SQL regular and mybatis regular

This time I will bring you a detailed explanation of the use of SQL regularity and mybatis regularity. What are the precautions for the detailed use of SQL regularity and mybatis regularity? The following is a practical case, let's take a look.

The other type of pattern matching provided by mysql is the use of extended regular expressions.

When you test for matches on such patterns, use the REGEXP and NOT REGEXP operators (or RLIKE and NOT RLIKE, which are synonyms).

Some characters that extend regular expressions are:

"." matches any single character.
A character class "[...]" matches any character within square brackets. For example, "[abc]" matches "a", "b", or "c". To name a range of characters, use a "-". "[a-z]" matches any lowercase letter, while "[0-9]" matches any number.
" * " matches zero or more of the things preceding it. For example, "x*" matches any number of "x" characters, "[0-9]*" matches any number of digits, and ".*" matches any number of anything.

Regular expressions are case-sensitive, but if you wish, you can use a character class to match both writings. For example, "[aA]" matches a lowercase or uppercase "a" and "[a-zA-Z]" matches any letter written either way.

Patterns match if it appears anywhere in the value being tested (SQL patterns match as long as they match the entire value).

To position a pattern so that it must match the beginning or end of the value being tested, use "^" at the beginning of the pattern or "$" at the end of the pattern.

To illustrate how extended regular expressions work, the LIKE query shown above is rewritten below using REGEXP:

To find names starting with "b", use the "^" match The beginning of the name and "[bB]" matches lowercase or uppercase "b":

mysql> SELECT * FROM pet WHERE name REGEXP "^[bB]";

Use regular expressions in Myabtis yourself

 select code,label from institution where admlvl = '2' and code REGEXP "[0-9]*\.[0-9]*"   select code,label from institution where admlvl = '3' and code REGEXP "[0-9]*\.[0-9]*\.[0-9]*"   select code,label from institution where admlvl = '4' and code REGEXP "[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*"; 

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