Inner join, outer join, cross join? What gives?

It’s a valid question. I once saw a Visual Basic code with T-SQL codes embedded in it. The VB code retrieves table records with multiple SELECT statements, one SELECT * per table. Then, it combines multiple result sets into a record set. Absurd?

To the young developers who did it, it was not. But when they asked me to evaluate why the system was slow, that issue was the first to catch my attention. That’s right. They never heard of SQL joins. In fairness to them, they were honest and open to suggestions.

How do you describe SQL joins? Perhaps, you remember one song – Imagine by John Lennon:

You may say I’m a dreamer, but I’m not the only one.

I hope someday you’ll join us, and the world will be as one.

#sql server #inner join #sql join #t-sql #sql