+sub alter_column_callback {
+ my( $proto, $dbh, $table, $old_column, $new_column ) = @_;
+ my $old_name = $old_column->name;
+ my $new_def = $new_column->line($dbh);
+
+# this would have been nice, but it appears to be doing too much...
+
+# return {} if $old_column->line($dbh) eq $new_column->line($dbh);
+#
+# #{ 'sql_alter' =>
+# { 'sql_alter_null' =>
+# "ALTER TABLE $table CHANGE $old_name $new_def",
+# };
+
+ return {} if $old_column->null eq $new_column->null;
+ { 'sql_alter_null' =>
+ "ALTER TABLE $table MODIFY $new_def",
+ };
+
+
+}
+