I have a large report I am running on sql server. It takes several minutes to run. I don't want users clicking run twice. Since i wrap the whole procedure in a transaction, how do I check to see if the table is locked by a transaction? If so I would want to return an error message saying "report generating, please try again in a few minutes".
How can this be accomplished?
SELECT
db_name(rsc_dbid) AS 'DATABASE_NAME',
case rsc_type when 1 then 'null'
when 2 then 'DATABASE'
WHEN 3 THEN 'FILE'
WHEN 4 THEN 'INDEX'
WHEN 5 THEN 'TABLE'
WHEN 6 THEN 'PAGE'
WHEN 7 THEN 'KEY'
WHEN 8 THEN 'EXTEND'
WHEN 9 THEN 'RID ( ROW ID)'
WHEN 10 THEN 'APPLICATION' end AS 'REQUEST_TYPE',
CASE req_ownertype WHEN 1 THEN 'TRANSACTION'
WHEN 2 THEN 'CURSOR'
WHEN 3 THEN 'SESSION'
WHEN 4 THEN 'ExSESSION' END AS 'REQUEST_OWNERTYPE',
OBJECT_NAME(rsc_objid ,rsc_dbid) AS 'OBJECT_NAME',
PROCESS.HOSTNAME ,
PROCESS.program_name ,
PROCESS.nt_domain ,
PROCESS.nt_username ,
PROCESS.program_name ,
SQLTEXT.text
FROM sys.syslockinfo LOCK JOIN
sys.sysprocesses PROCESS
ON LOCK.req_spid = PROCESS.spid
CROSS APPLY sys.dm_exec_sql_text(PROCESS.SQL_HANDLE) SQLTEXT
The simplest way to check if a table is locked is by updating a field in that table. If the table is locked you will get an error message similar to this:
ERROR 1099 (HY000): Table 'accounts' was locked with a READ lock and can't be updated MariaDB [test]>
So just create an 'UPDATE query (or another query that does an operation) to the table you want to check and see if you get the error message above.
Have you ever forgotten to lock the door to your house? the only way to check if the door is LOCKED is by you manually checking if the door opens.. that's the best way i can describe it.