In SQLite, the UNION operator creates a compound SELECT statement that returns the results of the left and right SELECT statements. In other words, it combines the results from two queries into a single result set.
operators
Fix “ERROR 1054 (42S22): Unknown column ‘colname’ in ‘order clause'” in MariaDB
If you’re getting error “ERROR 1054 (42S22): Unknown column ‘colname’ in ‘order clause’” in MariaDB, it may be that you’re trying to reference an aliased column by its column name.
This is a common error when running queries that join two or more tables. It can also happen when using operators such as UNION, INTERSECT, and EXCEPT.
Fix Error 1064 (42000) when using the MINUS Operator in MariaDB
There are at least a few possible reasons you might be getting the dreaded error 1064 (42000) that reads “You have an error in your SQL syntax…” etc when trying to use the MINUS operator in MariaDB.
I’ll explore these below and offer some solutions.
MySQL UNION Clause
In MySQL, the UNION clause combines the results from multiple queries into a single result set.
Oracle MINUS Operator Explained
In Oracle Database, the MINUS operator is used to return only unique rows returned by the first query but not by the second.
How UNION Works in PostgreSQL
In PostgreSQL, the UNION operator combines the results from multiple queries into a single result set.
How INTERSECT Works in PostgreSQL
In PostgreSQL, the INTERSECT operator combines two queries, but returns only those rows that are returned in both queries.
How EXCEPT Works in PostgreSQL
In PostgreSQL, the EXCEPT operator returns rows that are returned by the left input query that aren’t returned by the right input query. This can also be referred to as the difference between two queries.
Oracle UNION Operator Explained
In Oracle Database, the UNION operator allows us to combine the results from two queries into a single result set.