Handle TernaryExpr with alias in WITH clause

Added case for TernaryExpr in explainWithElement to properly output
the alias from WITH clause. Ternary expressions (? :) become
Function if with the alias from the WITH element.

Fixes stmt1 in 03254_uniq_exact_two_level_negative_zero.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: kyleconroy

internal/explain/expressions.go

@@ -1142,6 +1142,17 @@ func explainWithElement(sb *strings.Builder, n *ast.WithElement, indent string,
 		}
 		fmt.Fprintf(sb, "%s ExpressionList (children %d)\n", indent, 1)
 		Node(sb, e.Operand, depth+2)
+	case *ast.TernaryExpr:
+		// Ternary expressions become if functions with alias
+		if n.Name != "" {
+			fmt.Fprintf(sb, "%sFunction if (alias %s) (children %d)\n", indent, n.Name, 1)
+		} else {
+			fmt.Fprintf(sb, "%sFunction if (children %d)\n", indent, 1)
+		}
+		fmt.Fprintf(sb, "%s ExpressionList (children %d)\n", indent, 3)
+		Node(sb, e.Condition, depth+2)
+		Node(sb, e.Then, depth+2)
+		Node(sb, e.Else, depth+2)
 	default:
 		// For other types, just output the expression (alias may be lost)
 		Node(sb, n.Query, depth)

parser/testdata/03254_uniq_exact_two_level_negative_zero/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt1": true
-  }
-}
+{}