Let’s think we write a select statement and would like to DECODE (on Oracle database) on a column:

DECODE(bew.bewart_tid, ‘GDL’, ‘Grenzüberschr. Dienstl. aus EWR Raum’ ,bewart.bezeichnung) col_alias

Now you’d like to decode an additional value on the same column. This could result in a not-well-readable DECODE expression. Better you try to use the CASE expression:

, case when bew.bewart_tid = ‘GDL’ then ‘Grenzüberschr. Dienstl. aus EWR Raum’ when bew.bewart_tid = ‘GDLA’ then ‘Grenzüberschr. Dienstl. aus EWR Raum’ else bewart.bezeichnung end col_alias

This is a well-formed and well-readable SQL statement.

Update on CASE expression in Oracle SQL statement 🔗

When working with Oracle databases, the CASE expression is a powerful tool for conditional logic in SQL statements. In 2011, the use of the CASE expression was recommended as an alternative to the DECODE function for better readability and maintainability of code.

As we move into the year 2024, the recommendation to use the CASE expression in Oracle SQL statements remains valid. The CASE expression allows for easier handling of multiple conditions and results in more readable code compared to nested DECODE functions.

In a recent update, Oracle has continued to support and optimize the CASE expression for improved performance and functionality. Developers are encouraged to leverage the CASE expression for complex conditional logic in SQL queries.

For example, when writing a select statement in Oracle SQL and wanting to decode values based on certain conditions, the CASE expression can be used as follows:

SELECT
    CASE 
        WHEN bew_bewart_tid = 'GDL' THEN 'Grenzüberschreitender Dienstleistung aus EWR-Raum'
        WHEN bew_bewart_tid = 'GDLA' THEN 'Grenzüberschreitender Dienstleistung aus EWR-Raum'
        ELSE bewart_bezeichnung 
    END AS col_alias
FROM
    your_table;

This updated SQL statement showcases the use of the CASE expression to handle different scenarios based on the value of the bew_bewart_tid column. The code is clear, concise, and easy to understand, making maintenance and debugging more straightforward.

In conclusion, as of 2024, the CASE expression remains a valuable tool in Oracle SQL statements for handling conditional logic effectively. Developers are advised to utilize the CASE expression for improved code readability and maintainability in Oracle database queries. Stay updated with Oracle’s latest developments to make the most of its features and optimizations in your projects.