Handle ORDER BY with ASC/DESC modifiers in CREATE TABLE (#120)

Parse ASC/DESC modifiers after non-parenthesized ORDER BY expressions in
CREATE TABLE statements. When modifiers are present, output the column
wrapped in StorageOrderByElement in EXPLAIN AST output.

Author: claude

internal/explain/statements.go

@@ -446,7 +446,13 @@ func explainCreateQuery(sb *strings.Builder, n *ast.CreateQuery, indent string,
 		if len(n.OrderBy) > 0 {
 			if len(n.OrderBy) == 1 {
 				if ident, ok := n.OrderBy[0].(*ast.Identifier); ok {
-					fmt.Fprintf(sb, "%s Identifier %s\n", storageIndent, ident.Name())
+					// When ORDER BY has modifiers (ASC/DESC), wrap in StorageOrderByElement
+					if n.OrderByHasModifiers {
+						fmt.Fprintf(sb, "%s StorageOrderByElement (children %d)\n", storageIndent, 1)
+						fmt.Fprintf(sb, "%s  Identifier %s\n", storageIndent, ident.Name())
+					} else {
+						fmt.Fprintf(sb, "%s Identifier %s\n", storageIndent, ident.Name())
+					}
 				} else if lit, ok := n.OrderBy[0].(*ast.Literal); ok && lit.Type == ast.LiteralTuple {
 					// Handle tuple literal - for ORDER BY with modifiers (DESC/ASC),
 					// ClickHouse outputs just "Function tuple" without children

parser/parser.go

@@ -2626,7 +2626,13 @@ func (p *Parser) parseTableOptions(create *ast.CreateQuery) {
 					}
 				} else {
 					// Use ALIAS_PREC to avoid consuming AS keyword (for AS SELECT)
-					create.OrderBy = []ast.Expression{p.parseExpression(ALIAS_PREC)}
+					expr := p.parseExpression(ALIAS_PREC)
+					create.OrderBy = []ast.Expression{expr}
+					// Handle ASC/DESC modifier after single non-parenthesized ORDER BY expression
+					if p.currentIs(token.ASC) || p.currentIs(token.DESC) {
+						create.OrderByHasModifiers = true
+						p.nextToken()
+					}
 				}
 			}
 		case p.currentIs(token.PRIMARY):

parser/testdata/03257_reverse_sorting_key/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt5": true
-  }
-}
+{}

parser/testdata/03257_reverse_sorting_key_simple/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt5": true
-  }
-}
+{}

parser/testdata/03257_reverse_sorting_key_zookeeper/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt3": true
-  }
-}
+{}

parser/testdata/03362_reverse_sorting_key_explicit_primary_key/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt2": true
-  }
-}
+{}

parser/testdata/03459-reverse-sorting-key-stable-result/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt2": true
-  }
-}
+{}

parser/testdata/03513_read_in_order_nullable/metadata.json

@@ -1,6 +1 @@
-{
-  "explain_todo": {
-    "stmt14": true,
-    "stmt36": true
-  }
-}
+{}