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Syntax scope requirements for (NOT)EXISTS #355

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Syntax scope requirements for (NOT)EXISTS
afs Feb 2, 2026
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WIP:scope
afs Mar 9, 2026
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28 changes: 28 additions & 0 deletions spec/index.html
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Expand Up @@ -8988,6 +8988,34 @@ <h4>Variable Scope</h4>
</tr>
</tbody>
</table>

<p>
Syntax forms `EXISTS` or `NOT EXISTS` can appear inside
<a href="#rExpression">expressions</a>.
Expressions appear in
<a href="#rFilter">`FILTER`</a>,
<a href="#rHavingClause">`HAVING`</a>,
and places where `AS` is permitted;
(<a href="#rBind">`BIND`</a>,
<a href="#rSelectClause">a select clause</a>,
and <a href="#rGroupClause">`GROUP BY`</a>).
</p>


<!-- @@ remove
<p>
Syntax forms `EXISTS` or `NOT EXISTS` appear inside
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@kasei kasei Feb 4, 2026 •
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This seems overly restrictive in suggesting that (not) exists only appears inside filters (and not other places where expressions can be used).

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@afs afs Feb 10, 2026

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Is this change enough?

"inside a FILTER and filters appear inside group graph patterns."
==>
"inside expressions <link to [127] Expression>."

Or something that enumerates the places that expressions occur, filter, AS, ORDER BY, (GROUP BY and HAVING are allow AS).

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@kasei kasei Feb 10, 2026

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Expression would be good, I think.

a `FILTER` and filters appear inside group graph patterns.
Let `F` be a syntax form `FILTER`
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@Tpt Tpt Feb 4, 2026

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F is not used anywhere after. Is it intentional?

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@afs afs Feb 10, 2026

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No, it's not intentional. (See Greg's comment).

It is trying to say that scope is modified only for the leaves of the AST that can set variables - BGPs and paths.

From there, the current row variables is in-scope by the usual rules and include the current row.

I'll revise it.

appearing inside group graph pattern `GP`,
then for all
syntax forms `EXISTS {P}` or `NOT EXISTS {P}`,
any variable that is in-scope for `GP` is
also in-scope for all group graph patterns,
basic graph patterns, and paths inside `P`.
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@rubensworks rubensworks Feb 3, 2026

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"...also in-scope for all group graph patterns, basic graph patterns, and paths inside P"
Does this mean only in-scope if P is precisely a group graph pattern, basic graph pattern, or path?
Or does it allow nesting? E.g. within optional or service?

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@afs afs Feb 10, 2026

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Nesting - any group graph pattern.

The requirement is to include the variables of the current row at the bottom then they get incorporated all the way up to P by the usual rules.

</p>
-->

<p>The variable `v` must not be in-scope at the point of the
`(expr AS v)` form. The scoping for `(expr AS v)`
applies immediately in `SELECT` expressions.
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