Updated regex to explicitly exclude sql constants.

Author: A-Baji

datajoint/declare.py

@@ -11,7 +11,7 @@
 
 UUID_DATA_TYPE = 'binary(16)'
 MAX_TABLE_NAME_LENGTH = 64
-CONSTANT_LITERALS = {'CURRENT_TIMESTAMP'}  # SQL literals to be used without quotes (case insensitive)
+CONSTANT_LITERALS = {'CURRENT_TIMESTAMP', 'NULL'}  # SQL literals to be used without quotes (case insensitive)
 EXTERNAL_TABLE_ROOT = '~external'
 
 TYPE_PATTERN = {k: re.compile(v, re.I) for k, v in dict(

datajoint/expression.py

@@ -9,6 +9,7 @@
 from .preview import preview, repr_html
 from .condition import AndList, Not, \
     make_condition, assert_join_compatibility, extract_column_names, PromiscuousOperand
+from .declare import CONSTANT_LITERALS
 
 logger = logging.getLogger(__name__)
 
@@ -313,9 +314,9 @@ def proj(self, *attributes, **named_attributes):
         Each attribute name can only be used once.
         """
         # new attributes in parentheses are included again with the new name without removing original
-        duplication_pattern = re.compile(r'\s*\(\s*(?P<name>\w*[a-z]+\w*)\s*\)\s*$')
+        duplication_pattern = re.compile(fr'^\s*\(\s*(?!{"|".join(CONSTANT_LITERALS)})(?P<name>[a-zA-Z_]+\w*)\s*\)\s*$')
         # attributes without parentheses renamed
-        rename_pattern = re.compile(r'\s*(?P<name>\w*[a-z]+\w*)\s*$')
+        rename_pattern = re.compile(fr'^\s*(?!{"|".join(CONSTANT_LITERALS)})(?P<name>[a-zA-Z_]+\w*)\s*$')
         replicate_map = {k: m.group('name')
                          for k, m in ((k, duplication_pattern.match(v)) for k, v in named_attributes.items()) if m}
         rename_map = {k: m.group('name')