Using Python to read and write in a SQL Server database
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Below, I provide a snippet to read data from an Azure SQL Server database. Subsequently, it is written to another table in the same database. The trick here is to…
Hierarchical query in Oracle
Below, you find a nice example of an hierarchical query in Oracle. The idea is that you see the top-down hierarchy with some indications on the level that is shown.…
Size on Oracle
What is the size of an Oracle table? A very rough approximation is to multiply the number of rows with the average row length in bytes. Fortunately, Oracle directly provide…
Running totals in Oracle
Oracle has a nice possibility to calculate running totals. Assume we have a sales system where transactions are stored over time. We would like to know the running total –…
A completely useless PL SQL programme
Once, I wrote a completely useless programme – see below. I like to retain it as I spent quite some time on it. But it is absolutely useless. The idea…
Ranking in Oracle
Oracle has 3 analytical functions to rank data. They provide approximately the same results, but with little deviations. First the code: select salary, rank() over (order by salary) rank, dense_rank()…
Top 10 rows in Oracle
In previous versions of Oracle, we had to retrieve a top10 rows via a sub query. In the sub query, we ordered and retrieved the data whereas in the main…
External table
An external table is a flat file outside the Oracle database. If properly described in Oracle, it can be read as an Oracle table. The syntax consists of 3 elements:…
Change strings in Oracle
PL/SQL with the utl_file package allows us to manipulate strings in Oracle. One may read a string from a file, modify this and subsequently write it to another file. This…
Oracle and JSON
JSON stands for Java Script Object Notation. It is a way to describe and store data. It can be read and modified in any editor. It has components that describe…