diff --git a/schema/field.go b/schema/field.go
index d1a633ce..a6ff1a72 100644
--- a/schema/field.go
+++ b/schema/field.go
@@ -318,9 +318,10 @@ func (schema *Schema) ParseField(fieldStruct reflect.StructField) *Field {
 	}
 
 	if val, ok := field.TagSettings["TYPE"]; ok {
-		switch DataType(strings.ToLower(val)) {
+		lowerVal := DataType(strings.ToLower(val))
+		switch lowerVal {
 		case Bool, Int, Uint, Float, String, Time, Bytes:
-			field.DataType = DataType(strings.ToLower(val))
+			field.DataType = lowerVal
 		default:
 			field.DataType = DataType(val)
 		}
diff --git a/schema/relationship.go b/schema/relationship.go
index c60ff6d9..f1ace924 100644
--- a/schema/relationship.go
+++ b/schema/relationship.go
@@ -763,8 +763,9 @@ func (rel *Relationship) ToQueryConditions(ctx context.Context, reflectValue ref
 }
 
 func copyableDataType(str DataType) bool {
+	lowerStr := strings.ToLower(string(str))
 	for _, s := range []string{"auto_increment", "primary key"} {
-		if strings.Contains(strings.ToLower(string(str)), s) {
+		if strings.Contains(lowerStr, s) {
 			return false
 		}
 	}