Mysql RLIKE - match end of string or another character

Question

I'm trying to use RLIKE to match where a string of data is followed by either a specific character or an end of string ($). I get the expected results using just the end of string character ($), or just the expected character, or indeed any set of expected characters inside square brackets, but as soon as I go into square brackets for an expected character OR and end of string character, the end of line is not being matched.

Here is an example:

SQL data:

CREATE TABLE test_table (id int auto_increment primary key, search_string varchar(8));
INSERT INTO test_table (search_string) VALUES("123456789");
INSERT INTO test_table (search_string) VALUES("1234567");
INSERT INTO test_table (search_string) VALUES("123456");
INSERT INTO test_table (search_string) VALUES("12345");
INSERT INTO test_table (search_string) VALUES("12345E");

Example queries on this data:

SELECT count(*) FROM test_table WHERE search_string RLIKE "56[7]";
# the above returns fine - 2 rows (first and second)

SELECT count(*) FROM test_table WHERE search_string RLIKE "56[7YE]";
# the above returns fine - 2 rows (rows 2 and 5) as expected

SELECT count(*) FROM test_table WHERE search_String RLIKE "56$";
# the above returns fine - 1 rows (the third) as expected as 6 is followed by end of string

SELECT count(*) FROM test_table WHERE search_string RLIKE "56[7$]";
# the above returns only 1 row and should be 2 (rows 2 and 3 - '56' should be followed by a 7 or end of string)

Is there a special way to treat the $ character when it is in square brackets?

Answer 1

The regex may just need a slight tweak. Instead of 56[7$] instead you should use one of the following

56($|7)  
56($|[7YE])

Within [], the $ is attempting to match a literal dollar sign. You are instead looking for $ to match an end of line and so it can't be within square brackets.

Answer 2

This one worked when I tried it against your test data:

SELECT COUNT(*) FROM test_table WHERE search_string RLIKE '567{0,1}$'

I tried 56($|7) and it got rows 2 and 3, but it also got row 1

[Edit: {0,1} (one or more matches) is a special case represented by ?, so the expression could also be 567?$.]