A BAZILLION ROWS OF DATA! Has this ever happened to you? You have a working SQL query to retrieve data from a database table. Now you want to add a second table into the query, for related or more detailed data, and all of a sudden you have a bazillion pages of output. You have discovered the dreaded cross join effect. Despair not.

Whenever there are two tables in an SQL query, they will be joined. This means the rows of one table are combined with the rows of the other table. You must always pay attention to how you want them to be joined. With a bazillion rows, maybe you don't want a cross join. Other times, a cross join is exactly what you want. So let's look at this cross join effect more closely.