SQL AND OR Archives - SQL Training Online

How to write SQL from scratch in 1 hour.

**Full Beginner’s Course**

In this video I show you how to write SQL using SQL Server and SQL Server Management Studio. We go through Creating a Database, Creating Tables, Inserting, Updating, Deleting, Selecting, Grouping, Summing, Indexing, Joining, and other basics you need to get starting writing SQL.

Video: Learn Basic SQL

How to write SQL from scratch in 1 hour.

The following Scripts are used in the training:

--Create Database
Create Database Customer;

--Create Customer Table
create table Customer
(
	FirstName varchar(50),
	LastName varchar(50),
	Age int
);

--Insert Initial Data
insert into Customer (FirstName,LastName,[Age]) values ('Joey','Blue',40);
insert into Customer (FirstName,LastName,[Age]) values ('Barry','Bonds',50);
insert into Customer (FirstName,LastName,[Age]) values ('Mike','Schmidt',60);
insert into Customer (FirstName,LastName,[Age]) values ('Mike','Schmidt1',61);
insert into Customer (FirstName,LastName,[Age]) values ('Mike','Schmidt2',62);
insert into Customer (FirstName,LastName,[Age]) values ('Mike','Schmidt3',63);
insert into Customer (FirstName,LastName,[Age]) values ('Mike','Schmidt4',64);
insert into Customer (FirstName,LastName,[Age]) values ('Mike','Schmidt5',65);

--This deletes mike schmidt
/*
DELETE Customer
where FirstName='Mike'
and LastName Like 'Schmidt_';
*/

--Select Mike Schmidt
select *
from Customer
where FirstName='Mike'
and LastName Like 'Schmidt_';

--Update City on Barry Bonds
update Customer
Set City='Goddard'
where FirstName='Barry'
and LastName = 'Bonds' ;

--Add City to the Customer Table
alter table customer
add City varchar(50);

--Drop the Customer Table
drop table customer;

--Create Customer Table with Primary Key
create table Customer
(
	Id int Primary Key identity(1,1),
	FirstName varchar(50),
	LastName varchar(50),
	Age int,
	City varchar(50)
)

--Insert Customer Data
insert into Customer 
(FirstName,LastName,[Age],City) values ('Joey','Blue',40, 'Goddard');
insert into Customer 
(FirstName,LastName,[Age],City) values ('Barry','Bonds',50, 'San Francisco');
insert into Customer 
(FirstName,LastName,[Age],City) values ('Mike','Schmidt',60, 'KC');

--Create Products Table
create table Products
(
	id int primary key identity(1,1),
	ProductName varchar(50)
)

--Add Price to Products Table
alter table Products
add Price float;

--Select everything from Products table
select * from Products

--Insert Products
insert into Products (ProductName, Price) values ('Baseball', 5.95);
insert into Products (ProductName, Price) values ('Bat', 195.99);

--Create Orders Table
Create table Orders
(
	OrderId int primary key identity(1,1),
	OrderDate Datetime,
	CustomerID int,
	ProductID int
)

--Insert Orders
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),1,1);
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),1,1);
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),2,1);
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),2,1);
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),2,2);
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),2,2);
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),2,2);
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),2,2);
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),3,2);
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),3,2);
insert into Orders (OrderDate,CustomerID,ProductID) values (GetDate(),4,2); --Bad Record

--Select from Tables
select * from Orders;
select * from Products;
select * from Customer;

--Delete Bad Order  **Your OrderId may be different
delete Orders
where OrderId=21;

--Add Foreign Keys to the Orders table
alter table orders
add foreign key (CustomerId) references Customer(Id);

alter table orders
add foreign key (ProductId) references Products(Id);

--Find the Total and Average Price per City
select c.City,sum(p.Price),AVG(p.price) Total
from Orders o 
inner join Products p on o.ProductID=p.id
inner join Customer c on o.CustomerID=c.Id
group by c.City

See the original SQL Training Course for Beginners video.

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.

Please leave and questions or comments below and let me know if you want me to talk about any other topics.