transactions

问题 I am dubbing some SP at work and I have discover that whoever wrote the code used a transaction on a single update statement like this begin transaction *single update statment:* update table whatever with whatever commit transaction I understand that this is wrong because transaction is used when you want to update multiple updates. I want to understand from the theoretical point, what are the implications of using the code as above? Is there any difference in updating the whatever table

问题 I was reading about MSSQL Locking for the first time, and it many places, the locking mechanism concepts depend on the existence of Transactions. I was wondering whether locking (in general) is possible without having any Transactions involved? 回答1: When no explicit transaction exists, each SQL statement is executed in an automatic (autocommit) transaction. Normal locking behavior will apply in that case and the locks released when the automatic transaction is completed as the statement

问题 I have two models, Users and Students . I want to insert data into these tables simultaneously. First, I save data into Students model and then into Users models. Now, if data doesn't successfully get inserted into Users model there is already an entry into Students table. What I want is data entries into both model only if data can be successfully saved in both. Now my controller code looks something like this: public function actionCreate() { $model = new Students(); $userModel = new Users(

问题 I have two models, Users and Students . I want to insert data into these tables simultaneously. First, I save data into Students model and then into Users models. Now, if data doesn't successfully get inserted into Users model there is already an entry into Students table. What I want is data entries into both model only if data can be successfully saved in both. Now my controller code looks something like this: public function actionCreate() { $model = new Students(); $userModel = new Users(

问题 Consider the sample code below. If the connection to the database is suddenly broken when on STEP 2 (i.e. 2nd command), then even if we try to rollback the transaction it will not rollback since there is no connection to the database server. In such a case, what happens to the transaction object on the database server side? Will it remain in a waiting mode? I have had this situation come up when I tried to run a long transaction in ADO.Net by connecting to database servers through a VPN

问题 Consider the sample code below. If the connection to the database is suddenly broken when on STEP 2 (i.e. 2nd command), then even if we try to rollback the transaction it will not rollback since there is no connection to the database server. In such a case, what happens to the transaction object on the database server side? Will it remain in a waiting mode? I have had this situation come up when I tried to run a long transaction in ADO.Net by connecting to database servers through a VPN

问题 I have three models: List, Food, and Quantity. List and Food are associated through Quantity via has_many :through. So each Quantity has three params: food_id, list_id, and amount (an integer). My aim is to create a new Quantity (associated with that list) each time a list is created. I wish to do this using a transaction so that all objects must be successfully created or else none will be. My main question is: where in my code should I write this transaction? I think it should be in the

问题 I’m working with multidocument mongodb transactions, and I’m getting an unexpected error. In my c++ app, using mongocxx driver, the steps I’m performing are the following: create session start transaction create a bulk_write 1 for this session, where I have multiple updates (~1000) to colletion 1 create another bulk_write 2 for this session, where I have multiple inserts (~1000) to collection 2 execute bulk_write 1 execute bulk write 2 commit transaction This is the code snippet for the

问题 Not sure if 'scope' is the correct term here. I am using Spring for JPA transaction management (with a Hibernate underneath). My method to preform database transaction is private, but since you can only set @Transactional on a class or on a public method Since this mechanism is based on proxies, only 'external' method calls coming in through the proxy will be intercepted. This means that 'self-invocation', i.e. a method within the target object calling some other method of the target object,

问题 Not sure if 'scope' is the correct term here. I am using Spring for JPA transaction management (with a Hibernate underneath). My method to preform database transaction is private, but since you can only set @Transactional on a class or on a public method Since this mechanism is based on proxies, only 'external' method calls coming in through the proxy will be intercepted. This means that 'self-invocation', i.e. a method within the target object calling some other method of the target object,