MySQL查询消除了此PHP代码的使用

Question

I have one query that INNER JOIN s Table A with Table B and Table C, and I have another query that INNER JOIN s Table A with Table D. I could achieve what I want to do by merging the 2 results, removing duplicates and ordering them in PHP code, but I want to know if MySQL has this functionality, I also think it'd be faster and easier to code once I understand it. Essentially, I want to have the results from Query 1 OR from Query 2. Perhaps the following will help:

Query 1:

SELECT pkAssociation, associations.strNameEn, associations.strNameFr
FROM associations
INNER JOIN eventassociations ON fkAssociation = pkAssociation
INNER JOIN events on fkEvent = pkEvent
WHERE events.enumDeleted = 'no'
GROUP BY pkAssociation

Query 2:

SELECT pkAssociation, associations.strNameEn, associations.strNameFr
FROM associations
INNER JOIN associationprograms AS aprogs ON aprogs.fkAssociation = associations.pkAssociation
GROUP by pkAssociation

The tables don't have anything else of relevance that don't show up in the query. I'm sorry if I'm not asking this correctly, I don't even know how to ask a question about this properly. If the column names or sample data is needed, then I can provide some. Sorry for the inconvenience and long post.

Answer 1

You want the UNION DISTINCT statement, placed between the two queries. This will combine the result sets from both and remove duplicates. You can then place your ORDER BY clause after all UNIONS (if you have one).

For example:

SELECT col1, col2 FROM tableA

UNION DISTINCT

SELECT col1, col2 FROM tableB

ORDER BY col2 DESC