SQL Query not consistent across different tables - mysql

Question

I have 3 tables.
Team name, Team win ratio, Team location.
Team name, Team win ratio, Team location, Team value, Team fan count.
Team name, Player name, Player salary.
Table 1
Table 2
Table 2
Team name
Team name
Team name
Team win ratio
Team win ratio
Team location
Team location
Team value
Team fan count
Player name
Player salary
I need to combine 2 tables out of the 3:
either Table 1 combine Table 3 based on same primary key Team name, or
Table 2 join Table 3 based on same primary key Team name.
When I combine table 1 and 3 by team name, the join works perfectly, resulting in results with columns: Team name, Team win ratio, Team location, Player name, Player salary. However, when doing table 2 and 3, I get no results, despite table 2 and table 1 being virtually the same thing.
I tried checking to see if Team name in table 1 and Team name in table 2 are the same by doing:
SELECT TABLE1.TEAMNAME, TABLE2.TEAMNAME
FROM TABLE1
JOIN TABLE2 ON TABLE1.TEAMNAME = TABLE2.TEAMNAME
Or something along those lines, and I get the table with columns: table1teamname and table2teamname side by side with no issues, and they are exactly the same. However, when I do something along the lines of:
SELECT TABLE2.TEAMNAME, TABLE3.TEAMNAME
FROM TABLE2
JOIN TABLE3 ON UPPER(TABLE3.TEAMNAME) LIKE ('%'||UPPER(TABLE2.TEAMNAME)||'%')
I get no results, whereas if trying something like:
SELECT TABLE1.TEAMNAME, TABLE3.TEAMNAME
FROM TABLE1
JOIN TABLE3 ON UPPER(TABLE3.TEAMNAME) LIKE ('%'||UPPER(TABLE1.TEAMNAME)||'%')
It works completely fine, and I get the two columns table2.teamname and table 3.teamname that are all similar (team name in table 3 is a longer version and capitalised) side by side but matching exactly.
Why would this issue occur? Table 1 and Table 2 are basically the same other than the addition of a couple columns in the table, with the same results, but one table having a little more columns per row.
So to recap, table 1 and 2 are exactly the same, but table 1 fuzzy match on team name with table 3 works and gives rows of data, whereas table 2 fuzzy match with table 3 gives no rows with no matched data. Why is this?

Answer 1

Maybe there is unexpected space padding. Check out the following:
CREATE TABLE names (
id int
, name varchar(20)
) charset=UTF8;
INSERT INTO names VALUES
(1, 'name1')
, (2, 'name1 ')
, (3, 'name2')
;
SELECT names.*
, 'name1' = names.name
, 'name1' LIKE CONCAT('%', names.name, '%')
FROM names
;
Result:
+------+--------+----------------------+-------------------------------------------+
| id | name | 'name1' = names.name | 'name1' LIKE CONCAT('%', names.name, '%') |
+------+--------+----------------------+-------------------------------------------+
| 1 | name1 | 1 | 1 |
| 2 | name1 | 1 | 0 |
| 3 | name2 | 0 | 0 |
+------+--------+----------------------+-------------------------------------------+
Full test case here
The extra trailing space pad on the name in row with id = 2 causes the equals comparison to match, but the LIKE comparison does not!
This behavior is supported by the SQL Standard for certain collations. See <character set specification> and "PAD SPACE characteristic".
Updated:
SELECT names.*
, 'name1' = names.name
, 'name1' LIKE CONCAT('%', names.name, '%')
, 'name1' LIKE names.name
FROM names
;
+------+--------+----------------------+-------------------------------------------+-------------------------+
| id | name | 'name1' = names.name | 'name1' LIKE CONCAT('%', names.name, '%') | 'name1' LIKE names.name |
+------+--------+----------------------+-------------------------------------------+-------------------------+
| 1 | name1 | 1 | 1 | 1 |
| 2 | name1 | 1 | 0 | 0 |
| 3 | name2 | 0 | 0 | 0 |
+------+--------+----------------------+-------------------------------------------+-------------------------+
Updated test case here