sql check deadlock query
SELECT
xed.value('@timestamp', 'datetime2(3)') as CreationDate,
xed.query('.') AS XEvent
FROM
(
SELECT CAST([target_data] AS XML) AS TargetData
FROM sys.dm_xe_session_targets AS st
INNER JOIN sys.dm_xe_sessions AS s
ON s.address = st.event_session_address
WHERE s.name = N'system_health'
AND st.target_name = N'ring_buffer'
) AS Data
CROSS APPLY TargetData.nodes('RingBufferTarget/event[@name="xml_deadlock_report"]') AS XEventData (xed)
ORDER BY CreationDate DESC