Bug 616981: Make whine.pl work with PostgreSQL 8.4+ by fixing sql_string_until

Bugzilla/DB/Pg.pm

@@ -192,6 +192,18 @@ sub sql_string_concat {
     return '(CAST(' . join(' AS text) || CAST(', @params) . ' AS text))';
 }
 
+sub sql_string_until {
+    my ($self, $string, $substring) = @_;
+
+    # PostgreSQL does not permit a negative substring length; therefore we
+    # use CASE to only perform the SUBSTRING operation when $substring can
+    # be found withing $string.
+    return "CASE WHEN " . $self->sql_position($substring, $string)
+                        . " != 0 THEN SUBSTRING($string FROM 1 FOR "
+                        . $self->sql_position($substring, $string) . " - 1)"
+		        . " ELSE $string END";
+}
+
 # Tell us whether or not a particular sequence exists in the DB.
 sub bz_sequence_exists {
     my ($self, $seq_name) = @_;