This includes such names used with qualifiers (see Section 9.2.2, Identifier Qualifiers). Note: because all the data must be converted to varchar due to the new first line containing column titles, formats need to be taken into account (for dates at least). Beginning with MySQL 8.0.32, use of the dollar sign as the first character in the unquoted name of a database, table, view, column, stored program, or alias is deprecated and produces a warning. Cloud-native wide-column database for large scale, low-latency workloads. Hence getting 2 rows returned by the group by despite sharing the same GROUP BY fields. Relational database service for MySQL, PostgreSQL and SQL Server. With alias names it seems to have treated those lines rows with a non matched row on the left join differently. Additionally, several table operators can be combined next to one another. I sorted it out with a bit of dynamic SQL to create the Union query. Finally realised that the problem appears to be my use of alias names rather than the actual column names. The names of the left operand are used as columns name for the result. I had the same issue from the same type of client.

Mysql union with alias column names