I'm working with SQL templates in Java and I'm trying to figure out how to nest a text block, specifically for an `IF` expression that I want to protect with a feature flag using `isBarEnabled()`. The main issue is that my SQL can be lengthy and complex. In a simplifying example, I started with something like:
```java
"""
SELECT
foo,
IF(
complex_multiline_expression, NULL,
another_complex_expression) AS bar
FROM
...
"""
``` Now, if I want to conditionally include the `IF` expression based on my feature flag, I thought of wrapping it like:
```java
"""
SELECT
foo,
{
isBarEnabled()
? """
, IF(
complex_multiline_expression, NULL,
another_complex_expression)
AS bar
"""
: ""}
FROM
...
"""
```
Will this compile? Or is there a better way without turning my complex SQL into a long single-line string or resorting to string concatenation? Any suggestions would be really helpful!
3 Answers
Using a method that returns your SQL fragment could also be a decent alternative. It allows you to keep your main query tidy, although you might lose some context with table aliases if you extract them. Just keep in mind that it could lead to more code changes later if the feature flag is no longer needed.
It seems like you might want to simplify your approach here. Using feature flags within complex SQL can indeed make it harder to read. It could be better to extract your logic into separate queries instead. The DBMS's query optimizations can get tricky, especially when you're relying on nested templates like this. Just be aware that readability often trumps fancy solutions!
I totally agree! Extracting to separate queries definitely helps keep things clean and understandable while allowing room for optimization.
JEP-465 was actually withdrawn because they decided they could simplify it further. Brian Goetz mentioned in a recent announcement that while the need for this feature is recognized, the current proposals lacked clarity. So unfortunately, don't expect these templates to land anytime soon.
That makes sense. I guess we'll have to wait and see how they plan to address it.
That's true, moving SQL logic around can be a headache, especially with the specifics tied to the main query structure.