Recent Articles

SQL,

Bad SQL. SQL anti patterns in OUTER joins

You often need to find both matched and unmatched rows between two or more tables. As we all know we use OUTER joins in SQL to achieve this. However, there…

Uli Bethke August 29, 2023

SQL, FlowHigh,

SQL antipatterns: SELECT DISTINCT

The DISTINCT operator The DISTINCT operator is used to eliminate duplicates in a resultset, e.g. we can use it to identify the unique number of customers who made a purchase.…

Uli Bethke August 9, 2022

SQL, flexter,

Converting and Masking Connexo XML to a database (MySQL)

In this post we will show you how obfuscate XML data and convert it to a tabular format. We will use XML documents from Connexo NetSense and convert it to…

Maciek August 13, 2019

SQL,

Converting Financial Information eXchange XML (FIXML) to MS SQL Server

FIX is a messaging standard used for trades in the financial services industry. The FIX Trading Community is the independent body behind the FIX messaging standard. FIX messages are encoded…

Maciek June 5, 2018

SQL,

SQL on Hadoop, BigQuery, or Exadata. Please don’t call them MPP.

I often hear people referring to SQL engines running against HDFS or object storage as MPP. Strictly speaking this is incorrect. Let me first explain what an MPP database is…

Uli Bethke May 10, 2018

SQL,

Comparing Window Function Features by Database Vendors

We will round off the series on window functions with comparison of what database vendors offer. There are various mutations of window functions and every vendor supports a different subset…

Uli Bethke September 15, 2017