(MySQL) How to tell if a numeric variable is contained in a field in a table, and lists all the data in the table that contains the variable. How to Handle

(MySQL) How to tell if a numeric variable is contained in a field in a table and lists all the data in the table that contains the variable.
This table contains the following fields
ID csite ....
1 1,2,13 ....
2 2,3,4 ....
3 1,4,5 ....
4 2,5,23 ....
5 1,3,8 ....

Suppose you get a number variable 3, how to list all rows of data that contain the number 3

Use Select Id,csite from table where csite like '%3% ' or csite like '%3,% ' or csite like '%,3,% ' or csite like '%,3% '

It's not going to work, you'll find 13,23.

The desired result is:
ID csite ....
2 2,3,4 ....
5 1,3,8 ....

Looked up some information, with this charindex (3,csite) >0 tried no matter what to do??

Don't be too complicated SQL statements and stored procedures

Thank you!!!!!



------Solution--------------------
You can use MySQL's own function find_in_set

Find_in_set (Str,strlist)
Returns a value if the string str is in the list strlist consisting of n substrings, returns a 1 to N. A list of strings is made up of multiple substrings separated by the character ",". If the first argument is a constant string, and the second argument is a set column type, the Find_in_set () function is optimized to use bitwise operations! If STR is not strlist or if Strlist is an empty string, the return value is 0. If either parameter is NULL, the return value is also null. If the first parameter contains a ",", this function will not work at all:
mysql> SELECT find_in_set (' B ', ' a,b,c,d ');
2

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