transactions

问题 I have read about how REPEATABLE READ causes locks held by SELECT statements to be held to the end of the transaction. Is the same true for exclusive locks taken by UPDATE statements? Consequentially, is it the case that when I UPDATE a row in a transaction, subsequent SELECTs will return the value left by the UPDATE? So I understand that if I SELECT a row in transaction 1, then transaction 2 cannot UPDATE it until transaction 1 completes. However, if I UPDATE The row in transaction 1, will

问题 Account has embedded Transactions amount (positive for received transactions, negative for outgoing transactions) User wants to send money. We need to compute account's balance to check if there is enough money. In pseudocode: send_money(amount) balance = sum(account's all transactions) // Mongo Query 1 if (amount <= balance) add a new transaction to account // Mongo Query 2 But isn't it possible that two concurrent mongo connections both pass Query 1 and proceed to make Query 2? Say user's

问题 How can I set XACT_ABORT to ON (or OFF) from within ADO.NET ? 回答1: Execute SET XACT_ABORT ON or SET XACT_ABORT OFF . 回答2: There is no client setting: in SQL As Remus said. SET XACT_ABORT is not a property of the connection, command or transaction and can be set/unset at any time in SQL Code. There is no ado.net options for SET NOCOUNT ON etc. 来源： https://stackoverflow.com/questions/2277254/how-to-set-xact-abort-within-ado-net

问题 I'm using the following format for commiting changes to my db using linq. Begin Transaction (Scope Serialized, Required) Check Business Rule 1...N MyDataContext.SubmitChanges() Save Changes Done In Previous Query To Log File End Transaction Scope But in the SQL Server profiler I see the following line in the Connection:Start. set transaction isolation level read committed I went through this (http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/93a45026-0425-4d49-a4ac

问题 In DB2 , I need to do a SELECT FROM UPDATE, to put an update + select in a single transaction. But I need to make sure to update only one record per transaction. Familiar with the LIMIT clause from MySQL's UPDATE option places a limit on the number of rows that can be updated I looked for something similar in DB2's UPDATE reference but without success. How can something similar be achieved in DB2? Edit: In my scenario, I have to deliver 1000 coupon codes upon request. I just need to select

问题 In DB2 , I need to do a SELECT FROM UPDATE, to put an update + select in a single transaction. But I need to make sure to update only one record per transaction. Familiar with the LIMIT clause from MySQL's UPDATE option places a limit on the number of rows that can be updated I looked for something similar in DB2's UPDATE reference but without success. How can something similar be achieved in DB2? Edit: In my scenario, I have to deliver 1000 coupon codes upon request. I just need to select

问题 when user opens edit form for some entity, I would like to LOCK this entity and let her make any changes. During editing she needs to be sure that nobody else does any edit operations on it. How can I lock an entity in Entity Framework (C#) 4+, database MS SQL Server 2008? Thank you so much in advance! 回答1: There are two ways to handle these situations: Optimistic concurrency where you allow concurrent edits and inserts and catch exception if something violates concurrency rules. Optimistic

问题 when user opens edit form for some entity, I would like to LOCK this entity and let her make any changes. During editing she needs to be sure that nobody else does any edit operations on it. How can I lock an entity in Entity Framework (C#) 4+, database MS SQL Server 2008? Thank you so much in advance! 回答1: There are two ways to handle these situations: Optimistic concurrency where you allow concurrent edits and inserts and catch exception if something violates concurrency rules. Optimistic

问题 As far as I understood DataSourceTransactionManager binds a JDBC connection from the specified DataSource to the current thread, allowing for one thread-bound Connection per DataSource. If it's a pool of connections, it will take one of the available connections. After this if I use JdbcTemplate inside a transaction, it will capture a connection binded by DataSourceTransactionManager. Do I understand the mechanism correctly? A there any requirements for making transaction manager bean

问题 As far as I understood DataSourceTransactionManager binds a JDBC connection from the specified DataSource to the current thread, allowing for one thread-bound Connection per DataSource. If it's a pool of connections, it will take one of the available connections. After this if I use JdbcTemplate inside a transaction, it will capture a connection binded by DataSourceTransactionManager. Do I understand the mechanism correctly? A there any requirements for making transaction manager bean