From eaf98847a4c69d01f8d665e093437632de792540 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=BB=98=E5=85=B8?= <fudianchn@gmail.com>
Date: Sun, 23 Aug 2026 14:59:22 +0800
Subject: [PATCH] fix(parser): support MySQL hash line comments

A '#' followed by a blank now lexes as a line comment, the MySQL form
from issue #2499. '#' without a following blank keeps its current
lexing: identifier start (SQL Server #temp, ##global) and the JSON
operators #> / #>> are unchanged.

Signed-off-by: Fu Dian <fudianchn@gmail.com>
---
 .../net/sf/jsqlparser/parser/JSqlParserCC.jjt |  6 +++-
 .../parser/CCJSqlParserUtilTest.java          | 34 +++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt b/src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt
index 381f3afc1..1f358b03b 100644
--- a/src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt
+++ b/src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt
@@ -1845,7 +1845,11 @@ TOKEN : /* Numeric Constants */
 
 SPECIAL_TOKEN:
 {
-   < LINE_COMMENT: ("--" | "//") (~["\r","\n"])*>
+   // The `#` comment requires a following blank: `#` without one stays an
+   // identifier start (SQL Server `#temp`, `##global`) and `#>` / `#>>`
+   // JSON operators must keep their usual lexing (issue #1197, #1695).
+   < LINE_COMMENT: ("--" | "//") (~["\r","\n"])*
+       | "#" [" ", "\t"] (~["\r","\n"])*>
 }
 
 // Nested block comments:  /* ... /* ... */ ... */
diff --git a/src/test/java/net/sf/jsqlparser/parser/CCJSqlParserUtilTest.java b/src/test/java/net/sf/jsqlparser/parser/CCJSqlParserUtilTest.java
index dd9b55732..c3a9563a6 100644
--- a/src/test/java/net/sf/jsqlparser/parser/CCJSqlParserUtilTest.java
+++ b/src/test/java/net/sf/jsqlparser/parser/CCJSqlParserUtilTest.java
@@ -221,6 +221,40 @@ public void accept(Statement statement) {
         assertEquals(3, list.size());
     }
 
+    @Test
+    public void testLineCommentHashTrailing() throws Exception {
+        assertEquals("SELECT 1", CCJSqlParserUtil.parse("SELECT 1 # trailing comment").toString());
+    }
+
+    @Test
+    public void testLineCommentHashLeading() throws Exception {
+        assertEquals("SELECT 1", CCJSqlParserUtil.parse("# leading comment\nSELECT 1").toString());
+    }
+
+    @Test
+    public void testLineCommentHashWithinSelect() throws Exception {
+        assertEquals("SELECT 1 + 2, 3",
+                CCJSqlParserUtil.parse("SELECT 1 + 2 # note\n, 3").toString());
+    }
+
+    @Test
+    public void testHashWithoutBlankStaysIdentifier() throws Exception {
+        // without a following blank `#` is an identifier start, not a comment (#1197, #1695)
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT * FROM #temp");
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT * FROM ##global");
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT * FROM #$tab1#");
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT * FROM $#tab1#");
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT * FROM #$tab#tab1");
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT a#b FROM t");
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT 1 #note");
+    }
+
+    @Test
+    public void testHashJsonOperatorsStayOperators() throws Exception {
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT js #> '{a}' FROM t");
+        TestUtils.assertSqlCanBeParsedAndDeparsed("SELECT js #>> '{a,b}' FROM t");
+    }
+
     @Test
     public void testParseStatementsFail() throws Exception {
         String sqlStr = "select * from dual;WHATEVER!!";