It makes it clear that we are performing a cross join intentionally and not from accidentally omitting the join condition WHERE, which could happen when using the obsolete syntax for joining tables. SQL practitioners prefer to use the explicit CROSS JOIN keyword for this kind of operation. This is a workable solution for joining two tables when the objective is to get a result set with all possible combinations of the rows. The query will return a Cartesian product (a cross join), whose result set has the total number of rows equal to the number of rows in the first table multiplied by the number of rows in the second table. SELECT w.name AS wine, m.name AS main_course If what we want is every combination of rows from two tables, there is no need to include any joining conditions. With this syntax, we simply list the tables that we want to join in the FROM clause then use a WHERE clause to add joining conditions if necessary. One way to join two tables without a common column is to use an obsolete syntax for joining tables. There are at least two approaches to combining the wine and the main_course tables to get the result we need. In our first example, we want to see all possible combinations of wines and main courses from our menu. How to Combine two Tables Without a Common Column Let’s see how we can combine these tables to get the results we want. The main_course table contains the main course ID, the name, the supplier ID of the major supplier for this dish, and the price, for each dish: The wine table contains the wine ID, the wine name, the supplier ID, and the price: id We run a restaurant and have relevant data stored in multiple tables, among which are wine and main_course. Well, of course, it is! I’ll suggest a couple of solutions in this guide.īut first, let’s explore the data we’ll use for our examples. It sounds like it should be a pretty straightforward SQL assignment. In these cases, you would want to combine two or more tables without requiring a common column. You might want to combine all the information to generate a single table with all suppliers. They may even have different column names by product type (i.e., wines, juices, fruits, etc.). Or, imagine that the information about your suppliers are stored in different tables. As an example, if you run a restaurant, you might want to see all possible combinations of wines from your wine card and main courses from your menu. In other cases, you may want to have every combination of the rows from the two tables. It offers over 90 hands-on exercises on different kinds of JOINs, including joining more than two tables, non-equi joins, self-join, LEFT JOIN, FULL JOIN, and many more. If you are not familiar with this type of JOIN, check out our interactive SQL JOINs course. However, the real-world tasks of a data analyst are usually more diverse and complex.įor example, there are many use cases for a non-equi join, when two tables are combined using conditional operators other than the equal sign. When Do you Need to Join Tables Without a Common Column?īeginners just getting started with SQL are usually introduced to standard equi joins, in which two tables are combined by a common column. In this article, I’ll guide you through the different solutions with examples. The latter is technically not a join but can be handy for merging tables in SQL. Yes, you can! The longer answer is yes, there are a few ways to combine two tables without a common column, including CROSS JOIN (Cartesian product) and UNION.
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