Azure-Sql-Db

Our free SDU Tools for developers and DBAs, now includes a very large number of tools, with procedures, functions, and views. A while back, we added the ability to retrieve the version of the toolset programmatically, but an interesting request that we had, asked for the ability to query the toolset for the tools themselves. The Tools view now does that. The view returns the following columns: ToolName ToolTypeCode ToolType Category Description VideoURL

2025-02-03

After discussing LEFT OUTER JOIN, you might wonder if there is also a RIGHT OUTER JOIN. There is, and it’s the reverse of the left one. What a RIGHT OUTER JOIN from Products to ProductGroups says is that I want at least one row for every row in ProductGroups. You can see that in the query example above. The product group Hot Food currently has no products in it. The RIGHT OUTER JOIN causes it to be returned, as similar to what happens with a LEFT OUTER JOIN, the columns from the non-matching table are returned as NULL.

2025-02-03

The next type of join that I want to discuss in these posts is a left outer join. We use this mostly, when we know that not all rows are matching. For example, in the query shown above, I wanted to add up the ordered quantity values for all products. The problem is that if I used an INNER JOIN, I would only get products that match at least one order line.

2025-02-02

There are two ways you can write common join syntax. There’s an older way to write the query and a new way to write the query. In the image above, you can see the new way written first, and then the old way written below. The newer syntax was introduced as part of ANSI SQL, back in 1992. It has been recommended for over 30 years now. Comparison When you look at the older syntax, you’ll notice that I’m doing two things in the WHERE clause.

2025-02-01

The most common form of join between two tables is what’s called an inner join. In the example shown above, I’ve selected some columns from different tables. I’ve got description and product ID from the product table and I’ve got the product group name from the product group. What I wanted was a list of products but I want to know what group they’re part of. So to do that I had to use the products table, but I also had to join to the product groups table so I could get the name of the product group.

2025-01-31

A foreign key is a situation where we store the primary key of one table in another table. It’s very useful. For example, we might need to know which sales transactions were for which customers. Again, keep in mind that like primary keys, there could be more than one column in a key. While a foreign key can reference a unique key, it’s almost always the primary key. In the example shown above, the column OrderID is the primary key of the Orders table.

2025-01-30

In the previous post, we saw how CROSS JOIN operations work. Now it’s rare for us to want to have every combination of the rows in each table. What we usually end up joining on are primary keys and foreign keys. So we should start by defining what primary keys are. The primary key of a table is a value or combination of values that uniquely identifies a particular row in a table.

2025-01-29

The simplest way to join two tables is what’s called a cross-join. So this is where I say from products, cross-join, sales territories. SELECT * FROM dbo.Products CROSS JOIN dbo.SalesTerritories; Now what that will do though is it will give me every combination of rows from the two tables. So I’ll get one row from the second table for each row in the first table. This is often called a Cartesian product of the two tables and it can quickly end up generating a very large number of rows.

2025-01-28

Most programming languages have some way of forming loops. Now some of them have a variety. For example, a language like Basic or Excel had a For Next loop, a Do While loop, a While Until loop, etc. In T-SQL, while you could conceivably construct loops manually by using a GOTO statement, no-one does that and it would be considered a bad idea. Instead, we form all the loops we need by using a WHILE statement.

2025-01-27

In general, we try to avoid procedural logic when writing T-SQL. However, it is possible. The most basic procedural statement is the IF statement. It allows us to apply basic conditional logic. Instead of keywords like CASE that allow you to apply logic to determine values, the IF statement allows you to decide which statements are executed. IF @Value > 10 PRINT 'Large'; The condition can also include other clauses linked with AND and OR:

2025-01-26