meaning of four matching characters in SQL Server
%represents zero or multiple arbitrary characters
_represents an arbitrary character
[] any single character within the specified range
[^] Not Specified any single character in the range
strings with matching characters must be enclosed by quotation marks, for example, the following example:
like 'br % 'returns any string starting with "Br.
like 'br % 'returns any character starting with "Br.
like '% een' returns any string ending with "een.
like '% en %' returns any string containing "en.
like '_ en': returns a string of three characters ending with "EN.
like '[Ck] %' returns any string starting with "C" or "K.
like '[S-V] LNG' returns a four-character string ending with "ing ", starting from S to v
like'm [^ C] % ', return any string starting with "M" and the second character is not "C.
Note:
using the like operator usually causes SQL Server to use the associated index for the given table. It tells SQL Server to compare the specified string and find any content that matches the provided match. Because of this type of original fixation, it is not recommended to use this type of search or comparison in large tables, at least remind users that it is very important for the system to wait for data rows that meet the search criteria.