The CROSS JOIN query in SQL is used to generate all combinations of records in two tables. For example, you have two columns: size and color, and you need a result set to display all the possible paired combinations of those—that's where the CROSS JOIN will come in handy.A CROSS JOIN produces a cartesian product between the two tables, returning all possible combinations of all rows. It has no ON clause because you're just joining everything to everything. A FULL OUTER JOIN is a combination of a LEFT OUTER and RIGHT OUTER JOIN .The cross join is considered a very expensive statement in terms of data usage because it returns the product of the table being joined. If the first table contains 100 rows and the second has 1000 rows, the resulting cross join query will return 100 x 1000 rows, which is 100,000 rows.
Should I use cross join : When Should I Use Cross-Join Use a cross join when you want to generate all possible combinations of rows from two tables, regardless of any specific condition or relationship. It's suitable for scenarios where you need a complete pairing of every row from one table with every row from another.
Is cross join better than inner join
example if table1 contains 2 records and table2 contains 3 records then result of the query is 2*3 = 6 records. So dont go for cross join until you need that. The inner join will give the result of matched records between two tables where as the cross join gives you the possible combinations between two tables.
What is the biggest risk of using cross join : If the first table contains 100 rows and the second has 1000 rows, the resulting cross join query will return 100 x 1000 rows, which is 100,000 rows. The SQL Server document states that “this is potentially an expensive and dangerous operation since it can lead to a large data explosion.