Hello everyone, I need your help.

I need update the field `tbl_1.Class` in my DB MySQL, and try this query update, but I have this error, can you help me?

[Err] 2013 - Lost connection to MySQL server during query

Code:
UPDATE tbl_1
LEFT JOIN tbl_2 ON tbl_1.doDate = tbl_2.doDate
AND concat(
	tbl_1.doDate,
	' ',
	LEFT(tbl_1.doHour, 5),
	':00'
)>= subtime(
	concat(
		tbl_2.doDate,
		' ',
		LEFT(tbl_2.doHour, 5)
	),
	'0:01:00'
)
AND concat(
	tbl_1.doDate,
	' ',
	LEFT(tbl_1.doHour, 5),
	':00'
)<= addtime(
	concat(
		tbl_2.doDate,
		' ',
		LEFT(tbl_2.doHour, 5)
	),
	'0:01:00'
)
AND tbl_1.myCodeLine = tbl_2.myCodeLine
AND tbl_1.id <> tbl_2.id
SET tbl_1.Class = 'ok'
WHERE
	tbl_2.eLClass = 'tm';