SQL Server has a system stored procedure called sp_spaceused that enables you to check the size of a table in a database.
You can use it to check the number of rows, disk space reserved, and disk space used by a table, indexed view, or Service Broker queue in the current database, or the disk space reserved and used by the whole database.
Continue readingThe SQL alias is a nice little feature of SQL that allows you to write more concise code and create column names when no column name exists.
There are two SQL alias types; column aliases, and table aliases. In this article, I provide an overview of both.
Continue readingIn SQL Server, you can switch partitions in and out of a partitioned table.
You can do this with the ALTER TABLE statement. Basically, it goes like this:
ALTER TABLE OldTable
SWITCH TO NewTable PARTITION xThis switches the partition for OldTable into partition x of NewTable (where x is the partition number).
In SQL Server, partition switching allows you to load large amounts of data in or out of a table very quickly. This saves you from having to run delete or insert statements, and can be very useful when working with large data sets.
You can use the ALTER TABLE statement to switch a partition in or out of a table.
To switch a partition out of a table, the code goes like this:
ALTER TABLE Table1
SWITCH PARTITION x TO Table2This switches partition x from Table1 to Table2 (where x is the partition number).
This article contains basic SQL INSERT statements that beginners can use to insert data into their database tables.
This article contains basic SQL CREATE TABLE statements that beginners can use to create basic tables for their database projects.
I get it. You’re trying to learn SQL, but they won’t even tell you the most fundamental part – what you need to run SQL!
You’ve got the SQL code… but where do you actually run it? What software program do you need before you can run your SQL query against a database?
If that’s you, all is about to be revealed!
Continue readingIf you’re using OPENJSON(), but you’re trying to remember how to select an inner fragment from the JSON document, read on.
In SQL, the ORDER BY clause is commonly used to order the results of a query. It allows you to select one or more columns to order the results, and in most cases, it’s probably all you need.
But what if you need to make an exception?
What if you want the results to be ordered alphabetically, except for one row? Or several rows?
Or perhaps you simply want to put any NULL values to the end, while ordering the non-NULL results.
Either way, there’s a neat trick you can use that will enable you to do this. And the good part is, it’s simple.
You can cater for all of the above scenarios by adding a CASE expression to your ORDER BY clause.
Did you know that PostgreSQL is available in all Ubuntu versions by default?
Yes, that means that your Ubuntu 20.04 installation probably already has a PostgreSQL package sitting there waiting for you to install it.
And you can install it with one command, which I’ll show you below.
But what if you prefer to run the latest version of Postgres instead? Well, I’ll also show you how to install that. Installing the latest version is almost as easy as installing your local package.
Continue reading