The SQL AND OR is used when filtering with the SQL Where clause. More specifically, we are talking about the “AND” and the “OR” clauses.
Let’s start by looking at a basic SQL statement:
select * from customer
The customer table has the following records:
Now if we were to filter to just the “Dell” records, we would use the following query:
select * from customer where customer_company = 'Dell';
But, I want to get the “Dell” records and the “HP” records. To do that we would use the following query:
select * from customer where customer_company = 'Dell' or customer_company='HP';
And we get the following results:
Now, you are probably asking, “You said we want Dell AND HP records, why did we use the OR clause?”
It can be a little confusing, but here is how I think of it.
In the case where we want the company of Dell and HP, we are actually saying we want all of the records where the customer_company is Dell or the customer company is HP.
There is a never a case where the customer_company is both Dell and HP.
So let’s look at an example where we use the AND statement.
If, I wanted to get all of the Dell customers that have a name of Bill, I would use the following query:
select * from customer where customer_company = 'Dell' and customer_name='Bill';
In this case, I am actually looking for records where both criteria is met. Here is the result:
Those are the basics of using the SQL AND and OR clauses.
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