static int	DBpatch_2030094(void)
{
	...
		for (p = row[1]; '\0' != *p; p++)

mysql> SELECT triggerid,expression from triggers where expression='';
+-----------+------------+
| triggerid | expression |
+-----------+------------+
|         0 |            |
+-----------+------------+
1 row in set (0.04 sec)

mysql> delete from triggers where triggerid=0;
Query OK, 1 row affected (0.01 sec)

 25508:20160302:102726.414 completed 97% of database upgrade
 25508:20160302:102726.419 completed 98% of database upgrade
 25508:20160302:102726.421 completed 99% of database upgrade
 25508:20160302:102726.424 completed 100% of database upgrade
 25508:20160302:102726.424 database upgrade fully completed

mysql> show create table triggers\G
*************************** 1. row ***************************
       Table: triggers
Create Table: CREATE TABLE `triggers` (
  `triggerid` bigint(20) unsigned NOT NULL,
  `expression` varchar(2048) NOT NULL DEFAULT '',
  `description` varchar(255) NOT NULL DEFAULT '',
  `url` varchar(255) NOT NULL DEFAULT '',
  `status` int(11) NOT NULL DEFAULT '0',
  `value` int(11) NOT NULL DEFAULT '0',
  `priority` int(11) NOT NULL DEFAULT '0',
  `lastchange` int(11) NOT NULL DEFAULT '0',
  `comments` text NOT NULL,
  `error` varchar(128) NOT NULL DEFAULT '',
  `templateid` bigint(20) unsigned DEFAULT NULL,
  `type` int(11) NOT NULL DEFAULT '0',
  `state` int(11) NOT NULL DEFAULT '0',
  `flags` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY (`triggerid`),
  KEY `triggers_1` (`status`),
  KEY `triggers_2` (`value`),
  KEY `triggers_3` (`templateid`),
  CONSTRAINT `c_triggers_1` FOREIGN KEY (`templateid`) REFERENCES `triggers` (`triggerid`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql> select triggerid,CONCAT("'",expression,"'") as expression from triggers where triggerid=0;
+-----------+------------+
| triggerid | expression |
+-----------+------------+
|         0 | ''         |
+-----------+------------+
1 row in set (0.00 sec)

mysql>

static int	DBpatch_2030094(void)
{
	...
	char		..., *expr = NULL, ...;
	...
/* loop breaks on the very first iteration when p is empty string */
		for (p = row[1]; '\0' != *p; p++)
		{
			...
		}
/* taking else-branch */
		if (2048 < expr_offset && 2048 /* TRIGGER_EXPRESSION_LEN */ < zbx_strlen_utf8(expr))
		{
			...
		}
		else if (0 != strcmp(row[1], expr))	/* expr is still NULL, CRASH!!! */
		{
			...
		}
	...
}