JOIN by part of two column names Consider a table with the structure of

id            col1
WqDs.first
WqDs.second
eeRT.first
eeRT.second


How can I JOIN the table to itself using the first part of the id

SELECT idxx, a.col1 AS First, b.col1 AS Second
FROM table1 a JOIN table1 b ON ....

idxx(temporary)    First     Second
WqDs
eeRT


I tried LIKE but it works when an id exists in the id of another row. I thought to trim the first id of the first row and then find it in the second row, but there should be an easier way.
Use locate() to get the position of . and then left() to get the text left of it.

SELECT *
       FROM table1 t11
            INNER JOIN table1 t12
                       ON left(t12.id, locate('.', t12.id) - 1) = left(t11.id, locate('.', t11.id) - 1);