Handle comment column name correctly (#198)

Author: bakwc

mysql_ch_replicator/converter.py

@@ -1085,7 +1085,7 @@ def _strip_comments(self, create_statement):
             # Look for COMMENT keyword (case insensitive)
             if (i + 7 < len(create_statement) and 
                 create_statement[i:i+7].upper() == 'COMMENT' and
-                (i == 0 or not create_statement[i-1].isalnum()) and
+                (i == 0 or (not create_statement[i-1].isalnum() and create_statement[i-1] != '`')) and
                 (i + 7 >= len(create_statement) or not create_statement[i+7].isalnum())):
 
                 # Skip COMMENT keyword

test_mysql_ch_replicator.py

@@ -3314,6 +3314,21 @@ def test_charset_configuration():
         "CREATE TABLE test (id int comment 'lowercase', name varchar(255) Comment 'Mixed case')",
         "CREATE TABLE test (id int , name varchar(255) )"
     ),
+    # Field named comment
+    (
+        """CREATE TABLE test (
+            `departments int(11) NOT NULL,
+            `termine int(11) NOT NULL,
+            `comment` varchar(120) DEFAULT NULL,
+            PRIMARY KEY (departments,termine)
+        )""",
+        """CREATE TABLE test (
+            `departments int(11) NOT NULL,
+            `termine int(11) NOT NULL,
+            `comment` varchar(120) DEFAULT NULL,
+            PRIMARY KEY (departments,termine)
+        )"""
+    ),
 ])
 def test_strip_comments_function(input_sql, expected_output):
     """