![]() Just in case, you want duplicate values, then you have to use the UNION ALL clause. The UNION clause gives only unique values as output. Also, all the columns present in the SELECT statements must have similar data types. Here each SELECT statement used within the UNION statement must have the same number of columns in the same order. Let us get started! What is the SQL UNION operator?Īs the name suggests, this operator/ clause is used to combine the results of two or more SELECT statements. Differences between UNION and UNION ALL. ![]() In this article on SQL UNION, I will discuss the UNION operator used to retrieve data in the following sequence: Follow C# Corner to learn more new and amazing things about MySQL.While handling data in databases, we often tend to use the set operators in SQL, to retrieve data according to our requirements by combining two or more SELECT statements. In this article, I have discussed the concept of UNION in MySQL with various examples. ![]() We can use the ORDER BY clause with the UNION operator. Now, take some examples from a dummy database which I have attached to this article, in which we have some tables and data inside it. The below picture will illustrate the difference between the UNION statement and JOIN. The basic difference between the UNION and JOIN is that UNION combines the result set horizontally, whereas the JOIN statement combines the result sets vertically. This example shows the combination of two queries with one result set. Union Join is done by having 2 or more commands together by the UNION operator. Union Join allows the results of two commands to be combined into one output result. It just pulls all rows from all tables fitting our command specifics and combines them into a table. The UNION and UNION ALL are different in that UNION ALL will not drop duplicate rows and UNION eliminates duplicate rows. The UNION ALL operator selects all rows from each table and combines it into a single table. Now, try to understand the concept of UNION with a Venn diagram. ![]() Now, retrieve the result from the SELECT query / Without wasting time, let’s see the example CREATE DATABASE UNION_OPERATORS The unions are useful if you wish to join the results from more than one query, but be aware that the number of the returned columns by each select query should be the same.Įxample SELECT id,name FROM my_table UNION SELECT id,name FROM my_table The rows retrieved by each are combined and produced as the final command result. UNION allows retrieval of each set with a simpler WHERE clause in its own SELECT statement. We want to select several sets of rows from the same table, but some conditions that characterize each set are not easy to write as a single WHERE clause. UNION is useful because we have some information in multiple tables, and we want to fetch rows from all of them at once. ![]() The the union operator is used to combine the result set of two or more SELECT statements. UNION is used for combining two or more separate commands to return a single output. In this tutorial, I am going to explain working with MySQL UNION operator with examples. ![]()
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