how to avoid deadlock in sql server

What is a deadlock? ==================== A deadlock occurs when two system server process IDs (SPIDs) are waiting for a resource and neither process can advance because the other process is preventing it from getting the resource. for example, Andrew holds a lock on table A and requests a lock on table B; Lindsay holds a lock on table B and requests a lock on tab

Let's start with an example of this, which can cause deadlocks in SQL Server 2000 and 2005. In this article, I use the latest CTP (Community Technology Preview, Community Technology Preview) version of SQL Server 2005, and the same applies to SQL

Record the deadlock process and solution of the company's warehouse database server, and the warehouse database Four Conditions for deadlock: Mutual exclusion: resources cannot be shared and can only be used by one process. Hold and wait: processes that have obtained resources can apply for new resources again. No pre-emption: allocated resources cannot be forcib

Sessions 1 and Session 2 cannot continue until the other party frees resources. Therefore, SQL Server chooses a session in the deadlock as the "deadlock victim." Note: The deadlock victim's session will be killed and the transaction will be rolled back. Note: deadlocks and

large transaction, the transaction is too large to allow other sessions to wait for exclusive lock time to become longer 2, everyone is using the same nonclustered index, and scan the Pricingexpressproductcode field 3, the index of repeated values are many From the above symptoms can be basically judged, this nonclustered index is useless, you can disable the ALTER INDEX [ix_pricingexpressproductcode_state] on [dbo]. [Orderxxx] DISABLE After disabling, the

('dbcc inputbuffer ('+ @ spid + ')') If @ sign = 'deadlocked process' exec ('Kill '+ @ spid) Set @ I = @ I + 1 End End Else While @ I Begin Select @ s = 'dbcc inputbuffer ('+ Cast (process ID as varchar) +') 'from # t where id = @ I Insert # T1 exec (@ s) Set @ I = @ I + 1 End Select a. *, the SQL statement of the Process = B. eventinfo From # t a join # t1 B on A. ID = B. ID End Go Set quoted_identifier off Go Set

T1 reads the data, performs some actions, and then updates the data. Transaction T2 Do the same thing, T1 and T2 may overwrite each other's updates when updating the data, causing an error. A, a, two users read the same data and modify it, and one of the user's modifications destroys the result of another modification, such as a booking system The main method of concurrency control is to prevent users from doing certain operations over a period of time by locking to

complete code usage example:The above code will prevent SQL injection. Why is it?When prepare () is called, the query statement has been sent to the database server with only placeholders at this time? Send in the past, no user submitted data, when called to execute (), the user submitted values will be sent to the database, they are separate transmission, the two independent,

Label:"SQL Server 2005 deadlock resolution Exploration" mentioned earlier, deadlock severity, an average of one deadlock per day, and a lot of data and ideas in resolving and handling SQL server2005 deadlocks, and then we used the

Select T.username,count (*) from v$session T GROUP by T.username //Find the sql_id value that a user is executing based on the user group session Select * From V$session t where T.username = ' BUDGET ' and t.sql_id are NOT NULL //lookup corresponding SQL_ID's corresponding SQL statement select M.sql_text from V$session T, V$sqlarea m where t.username = ' BUDGET ' and t.sql_id = m.sql_id // SELECT * from V$sqlarea t where T. sql_id = ' G92sy7kwt6mrq '

The use of SQL Server as a database application system, will not be able to sometimes create a deadlock, after the deadlock, the maintenance personnel or developers will mostly only through the sp_who to find the deadlock process, and then killed with Sp_kill. With Sp_who_lo

( "SELECT COUNT (*) from user" $d = mysql_fetch_row ( $r $rand = mt_rand (0, $d [0]-1); $r = mysql_query ( "Select username from user LIMIT $rand, 1" 7. Avoid SELECT *The more data you read from the database, the slower the query becomes. And, if your database server and Web server are two separate servers, this also increases the loa