From 0a7aab1500a76c3bbd4cd056024eb208b4cfba8c Mon Sep 17 00:00:00 2001
From: Nick Woolmer <29717167+nwoolmer@users.noreply.github.com>
Date: Mon, 2 Dec 2024 17:03:28 +0000
Subject: [PATCH] add functions example

---
 documentation/reference/sql/declare.md | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/documentation/reference/sql/declare.md b/documentation/reference/sql/declare.md
index c8f97e2a..8ba680f9 100644
--- a/documentation/reference/sql/declare.md
+++ b/documentation/reference/sql/declare.md
@@ -74,6 +74,23 @@ SELECT @x + @y
 |--------|
 | 7      |
 
+### Variables as functions
+
+A variable need not be just a constant, it could be a function call, 
+and variables with function values can be nested:
+
+```questdb-sql title="declaring function variable" demo
+DECLARE
+  @today := today(),
+  @start := interval_start(@today),
+  @end := interval_end(@today)
+SELECT @today = interval(@start, @end)
+```
+
+| column |
+|--------|
+| true   |
+
 
 ### Declarations in subqueries