Joins and Unions are both used in a function to combine data that comes from 2 or more tables. Because of their similar function, many people confuse one to the other. If you’re one of these people who have a hard time identifying the differences between the two, then this article is perfect for you. Below, we will discuss the difference between join and union.
What’s the difference between join and union?
As said, both a join and a union have the ability to combine data from 2 or more tables. What is their difference? Their difference lies on the process by which data is combined.
To put it simply, joins combine data and put them into new columns. This means that if you join two tables together, the data that comes from the first table will be shown in the set of columns beside the column of the second table in the same row.
Unions, on the other hand, combine data and put them into new rows. If you union two tables together, the data that comes from the first table will be shown in one set of rows. In addition, the data that comes from the second table will be shown in another set. Under these circumstances, the rows come in the same result.
joins combine columns
With joins, rows are created whenever columns from a particular table match the columns from another table. This match is referred to as the join condition.
Joins are great for looking for values and then adding them to results, and this feature is the result of reversing normalization and using foreign key to look up the column values with the use of the primary key.
Unions combine rows
Unions are often used when there are two results with rows that have the same result.
Combining data using a join
An inner join is among the basic forms of join. It is used when there is a need to match certain rows from 2 tables.
Combining data using a Union
When you combine rows, the duplicate rows get eliminated. You need to keep ALL keywords if you plan to keep all the rows from the results of the select statements.