1 files changed, 25 insertions, 3 deletions
diff --git a/sqlglot/optimizer/canonicalize.py b/sqlglot/optimizer/canonicalize.py
index fc37a54..c5c780d 100644
--- a/sqlglot/optimizer/canonicalize.py
+++ b/sqlglot/optimizer/canonicalize.py
@@ -1,9 +1,12 @@
+from __future__ import annotations
+
 import itertools
 
 from sqlglot import exp
+from sqlglot.helper import should_identify
 
 
-def canonicalize(expression: exp.Expression) -> exp.Expression:
+def canonicalize(expression: exp.Expression, identify: str = "safe") -> exp.Expression:
     """Converts a sql expression into a standard form.
 
     This method relies on annotate_types because many of the
@@ -11,15 +14,18 @@ def canonicalize(expression: exp.Expression) -> exp.Expression:
 
     Args:
         expression: The expression to canonicalize.
+        identify: Whether or not to force identify identifier.
     """
-    exp.replace_children(expression, canonicalize)
+    exp.replace_children(expression, canonicalize, identify=identify)
 
     expression = add_text_to_concat(expression)
     expression = coerce_type(expression)
     expression = remove_redundant_casts(expression)
+    expression = ensure_bool_predicates(expression)
 
     if isinstance(expression, exp.Identifier):
-        expression.set("quoted", True)
+        if should_identify(expression.this, identify):
+            expression.set("quoted", True)
 
     return expression
 
@@ -52,6 +58,17 @@ def remove_redundant_casts(expression: exp.Expression) -> exp.Expression:
     return expression
 
 
+def ensure_bool_predicates(expression: exp.Expression) -> exp.Expression:
+    if isinstance(expression, exp.Connector):
+        _replace_int_predicate(expression.left)
+        _replace_int_predicate(expression.right)
+
+    elif isinstance(expression, (exp.Where, exp.Having)):
+        _replace_int_predicate(expression.this)
+
+    return expression
+
+
 def _coerce_date(a: exp.Expression, b: exp.Expression) -> None:
     for a, b in itertools.permutations([a, b]):
         if (
@@ -68,3 +85,8 @@ def _replace_cast(node: exp.Expression, to: str) -> None:
     cast = exp.Cast(this=node.copy(), to=data_type)
     cast.type = data_type
     node.replace(cast)
+
+
+def _replace_int_predicate(expression: exp.Expression) -> None:
+    if expression.type and expression.type.this in exp.DataType.INTEGER_TYPES:
+        expression.replace(exp.NEQ(this=expression.copy(), expression=exp.Literal.number(0)))