Aklakan commented on issue #3463:
URL: https://github.com/apache/jena/issues/3463#issuecomment-3346021186
I recall that there were databases that would incorrectly inject bindings
into unions. You can check with this query:
```sparql
SELECT * {
BIND("foo" AS ?foo)
{ BIND(?foo AS ?bar) } UNION { BIND(?foo AS ?baz) }
}
```
The expected result is this:
```
---------------------
| foo | bar | baz |
=====================
| "foo" | | |
| "foo" | | |
---------------------
```
Note: With Jena and Oxigraph (perhaps some more stores by now?), you can use
the `LATERAL` keyword to inject bindings from from the left-hand side (lhs) to
the right-hand one before the rhs gets evaluated. Unfortunately, this is not
yet standard/portable.
```sparql
SELECT * {
BIND("foo" AS ?foo)
LATERAL {
{ BIND(?foo AS ?bar) } UNION { BIND(?foo AS ?baz) }
}
}
```
```
-------------------------
| foo | bar | baz |
=========================
| "foo" | "foo" | |
| "foo" | | "foo" |
-------------------------
```
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