-char backsql_def_subtree_cond[] = "ldap_entries.dn LIKE CONCAT('%',?)";
-char backsql_def_upper_subtree_cond[] = "(ldap_entries.dn) LIKE CONCAT('%',?)";
-char backsql_id_query[] = "SELECT id,keyval,oc_map_id,dn FROM ldap_entries WHERE ";
+const char backsql_def_subtree_cond[] = "ldap_entries.dn LIKE CONCAT('%',?)";
+const char backsql_def_upper_subtree_cond[] = "(ldap_entries.dn) LIKE CONCAT('%',?)";
+const char backsql_id_query[] = "SELECT id,keyval,oc_map_id,dn FROM ldap_entries WHERE ";