![]() It does not matter if all the three tables have different column names. Mysql union and union all operators are used to get the combined result set two or more tables for two subqueries which involve using a select clause to. So if you want to emulate a Full join on MySQL take a look here. From the UNION operator, we know that all rows will be displayed from both the queries except the duplicate are once. The DISTINCT clause with UNION produced nothing extra as the simple UNION done. Assume the three tables have the following contents − 8 Answers Sorted by: 43 MySQL lacks support for FULL OUTER JOIN. Here UNION ALL have to avoid the elimination of duplicate rows. Suppose you have two tables that list prospective and actual customers, a third that lists vendors from whom you purchase supplies, and you want to create a single mailing list by merging names and addresses from all three tables. Whereas we use the UNION clause when we want to combine. You can use UNION if you want to select rows one after the other from several tables or several sets of rows from a single table all as a single result set. Using the JOIN clause, we combine the attributes of two given relations and, as a result, form tuples.
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