how to avoid deadlock in sql server

other transactions; a lock wait occurs. The second transaction attempted to get an exclusive (X) lock to update. A deadlock occurs because two transactions are converted to exclusive (X) locks, and each transaction waits for another transaction to release the shared-mode lock.To avoid this potential deadlock problem, use the update (U) lock. Only one transaction

indexes.As an example:Use [Testdb]gocreate TABLE [dbo]. [TestTable] ( [A] [int] PRIMARY KEY not NULL, [B] [varchar] () null) GOWe create a test table, and generally the best design is to add a primary key to this table.The concept of the primary key, I believe that almost understand the point of the database of children's shoes is not unfamiliar, two basic features: non-repetition, non-empty.Well, just these two points are used, the meaning of non-repetition is that the selectivity is hig

ordernum_03_cursor -- delete current line end fetch next from ordernum_03_cursor into @OrderId, @userId--Move cursor end 6. Close the cursor When the cursor is opened, the server specifically allocates a certain amount of memory space for the cursor to hold the data result set for the cursor operation, and some data is blocked by using the cursor. Therefore, once used, the cursor should be closed in a timely manner to

If you are in charge of a SQL Server-based project or you have just been in touch with SQL Server, you may have to face some database performance problems, this article will provide you with some useful guidance (most of which can also be used for other DBMS ).Here, I am not going to introduce the tips for using

Tags: style color ar using SP strong file data onSQL Server allows the user to set the database initial and maximum values, which can be configured by auto-grow or auto-shrink. With these configurations, we can prevent application modifications that could be caused by database space problems, or when SQL Server disk space is exhausted. In general, if the database

Tags: dynamic combined with MAC Max Sem named create summary Uninstall Preface This is my work more than two years later, starting from the most basic SQL start, seriously learn SQL Server, Leackage Check and consolidation have all; because I was just beginning to learn, always upset, recently changed work, found 1-2 years of experience, asked the basic thing or

converted to the exclusive (x) lock, and each transaction waits for another transaction to release the share mode lock, a deadlock occurs. To avoid this potential deadlock problem, use the update (u) Lock. Only one transaction can obtain the resource Update (u) Lock at a time. If the transaction modifies the resource, the update (u) Lock is converted to the row

SQL Server performance optimization skills, SQL Server Performance Optimization 1. Select the most efficient table name sequence (only valid in the rule-based Optimizer) The SQL Server parser processes the table names in the FROM

more fragile in algorithm capability. Not talking about performance, light from the data storage management, it is difficult to manage a large table with heaps. So in SQL Server, a clustered index is built on all large, frequently used tables. Because clustered indexes can avoid many problems.Clustered index StructureIn SQL