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SELECT UNION | 22/25 | UPV

Título: SELECT UNION Descripción automática: In this video, the presenter explains how to perform query joining in SQL with the UNION command, which concatenates the results from multiple SELECT queries. The database in question belongs to a food distributor and contains information about customers, employees, shippers, products, suppliers, and order details, all interconnected through foreign keys. The presenter outlines that UNION joins should have SELECT statements with an identical number of fields, ordered the same way, and with similar data types, although SQL attempts to adapt differing types. By default, UNION selects unique values; to include duplicates, one must use UNION ALL. An example illustrated in the video involves combining city data from Customers and Suppliers tables. The presenter demonstrates obtaining a list of cities with either customers or suppliers without repetition. For repeated entries, UNION ALL should be utilized. The speaker further showcases a query that retrieves order details for Dairy Products and Produce with certain conditions, such as a minimum total amount for the order details. By using UNION ALL, they merge the results of two complex SELECT queries, creating a comprehensive set of records that would be challenging to compile with a single SELECT statement. The video concludes by reiterating that UNION is used for distinct results and UNION ALL for including repeated values in combined queries. Autor/a: Despujol Zabala Ignacio Curso: Este vídeo es el 22/25 del curso MOOC Introduction to SQL and relational databases.    • MOOC Introduction to SQL and relation...   Inscríbete en: https://upvx.es/courses/course-v1:edx... Universitat Politècnica de València UPV: https://www.upv.es Más vídeos en:    / valenciaupv   Accede a nuestros MOOC: https://upvx.es #SQL (programming language) #SELECT UNION SQL #UNION SQL #OPERATORS SQL #COMMANDS SQL #