Our first Left Outer Join

SELECT * 
FROM 
	[Pets] LEFT JOIN [Owners]
ON 
	[Pets].OwnerID = [Owners].OwnerID

SELECT [Pets].[Name], [Owners].[Name]
FROM 
	[Pets] LEFT JOIN [Owners]
ON 
	[Pets].OwnerID = [Owners].OwnerID

Some tips and tricks

SELECT 
	A.[Name], B.[Name]
FROM 
	[Pets] AS A LEFT JOIN [Owners] AS B
ON 
	A.OwnerID = B.OwnerID
WHERE 
	LEFT(A.[Name], 1) = LEFT(B.[Name], 1)

Aliases for columns can be in two ways, let's check it out the first one:

-- ALIASES FOR COLUMNS
SELECT 
	A.[Name] AS PetName, B.[Name] AS OwnerName
FROM 
	[Pets] AS A LEFT JOIN [Owners] AS B
ON 
	A.OwnerID = B.OwnerID
WHERE 
	LEFT(A.[Name], 1) = LEFT(B.[Name], 1)

Or also you can write just as follows:

-- ALIASES FOR COLUMNS
-- No AS keyword for aliases
SELECT 
	A.[Name] PetName, B.[Name] OwnerName
FROM 
	[Pets] AS A LEFT JOIN [Owners] AS B
ON 
	A.OwnerID = B.OwnerID
WHERE 
	LEFT(A.[Name], 1) = LEFT(B.[Name], 1)

-- FULL CODE
-- ALIASES FOR TABLES
SELECT 
	A.[Name], B.[Name]
FROM 
	[Pets] AS A LEFT JOIN [Owners] AS B
ON 
	A.OwnerID = B.OwnerID
WHERE 
	LEFT(A.[Name], 1) = LEFT(B.[Name], 1)

-- ALIASES FOR COLUMNS
SELECT 
	A.[Name] AS PetName, B.[Name] AS OwnerName
FROM 
	[Pets] AS A LEFT JOIN [Owners] AS B
ON 
	A.OwnerID = B.OwnerID
WHERE 
	LEFT(A.[Name], 1) = LEFT(B.[Name], 1)

-- RIGHT JOINS
SELECT 
	A.[Name] AS PetName, B.[Name] AS OwnerName
FROM 
	[Owners] AS B RIGHT JOIN [Pets] AS A
ON 
	A.OwnerID = B.OwnerID

Inner join

-- INNER JOINS
SELECT * 
FROM [dbo].[Pets] AS A 
INNER JOIN [dbo].[ProceduresHistory] AS B
ON A.Petid = B.PetID

Complex JOINs

-- COMPLEX JOINS
SELECT * 
FROM
	[dbo].[Pets] AS A
INNER JOIN [dbo].[ProceduresHistory] AS B
ON 
	A.Petid = B.PetID
LEFT JOIN [dbo].[ProceduresDetails] AS C
ON
	B.ProcedureType = C.ProcedureType
AND
	B.ProcedureSubCode = C.ProcedureSubCode

Here we have combined 3 tables:

Pets, ProceduresHistory and ProceduresDetails