There is a performance hit when usingUNIONinstead ofUNION ALL, since the database server must do additional work to remove the duplicate rows, but usually you do not want the duplicates (especially when developing reports). UNION Example: SELECT'foo'ASbarUNIONSELECT'foo'ASbar Result: +---+|...
Example SELECTCity, CountryFROMCustomers WHERECountry='Germany' UNION SELECTCity, CountryFROMSuppliers WHERECountry='Germany' ORDERBYCity; Try it Yourself » SQL UNION ALL With WHERE The following SQL statement returns the German cities (duplicate values also) from both the "Customers" and the "...
Example: SQL UNION ALL Example: SQL UNION ALL With WHERE Clause -- select the union of age columns from both Teachers and Students tables where age >= 20SELECTage,nameFROMTeachersWHEREage >=20UNIONALLSELECTage,nameFROMStudentsWHEREage >=20; Run Code Here, the SQL command selects theagecolu...
UNION vs. UNION ALL Examples With Sort on Non-indexed Column Here is another example doing the same thing, but this time doing a SORT on a non indexed column. As you can see the execution plans are again identical for these two queries, but this time instead of using a MERGE JOIN, a...
C) Oracle UNION ALL example The following statement returns the unique last names of employees and contacts: SELECTlast_nameFROMemployeesUNIONSELECTlast_nameFROMcontactsORDERBYlast_name;Code language:SQL (Structured Query Language)(sql) The query returned 357 unique last names. ...
The next 2 examples shows that we would return results whether we used UNION or UNION ALL since all required criteria are met. This final example would fail. While we have the correct number of columns, they are now queried in the wrong order in the second SELECT statement and thus the ...
UNION ALL SELECT column1, column2, ... FROM table2; The following example selects the first and last name from the actor and customer tables in the Sakila database: SELECT first_name, last_name FROM actor UNION ALL SELECT first_name, last_name ...
You can get a union of lists in Python using many ways, for example, by using thefor loop,union(),set(),+operator,|operator,itertoolsandextend()functions. In this article, I will explain how to get a union of lists by using all these methods with examples. ...
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Example:The union of the companies went smoothly and everyone is benefitting. Where doesunioncome from? The first records of the termunioncome from the 1400s. It comes from the Late Latinūniō, meaning “oneness.” When auniontakes place, multiple things come together to make one. ...