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The Android system actually has a built-in database. SQLite is a lightweight relational database. It has very fast operation speed and occupies very few resources. It usually only needs a few hundred KB of memory, so it is especially suitable for mobile devices. SQLite not only supports the standard SQL syntax, but also follows the ACID t ...

1, Use annotations for associations   user configuration table <mapping resource="org/zttc/itat/model/User.hbm.xml"/> <mapping class="org.zttc.itat.model.User"/> It replaces the original xml Class level annotation @The entity annotation declares a class as an entity Bean. Entity must have @ Id. You can generate a Tabl ...

Primary library initial instantiation Only initial instantiation of the primary database is required to build a Dameng active standby database. If there are instances and data in the primary database, the original database can be used. Now select the data copy method to synchronize instance data, so only the primary database instance is in ...

Theoretical introduction First, the map is used to illustrate how redis implements the delay queue When the user sends a message request to the server background, the server will detect whether the message needs delay processing. If necessary, it will be put into the delay queue and detected and processed by the delay task detector. For t ...

Since the original / prepared SQL query is often executed in a simple way, you can use serialize Query method By default, the function will return two parameters - a result array and an object containing metadata (such as the number of rows affected, etc.) Please note that since this is an original query, the metadata is specific dialect Some ...

"The ancients' knowledge is weak, but their Kung Fu can only be achieved when they are young and old." One article takes you from the introduction to the mastery of nodejs. In fact, the cost of learning nodejs is not so high. You only need this article from brother feitu. Ten minutes will take you from the introduction to the master ...

Is Redis single threaded and high-performance Redis single threaded? The single thread of Redis mainly means that the network IO and key value pair reading and writing of Redis are completed by one thread, which is also the main process of Redis providing external key value storage services. However, other Redis functions, such as persistenc ...

6.1 introduction to database transactions Transaction: a set of logical operation units that transform data from one state to another. Transaction processing (transaction operation): ensure that all transactions are executed as a unit of work. Even in case of failure, this execution mode cannot be changed. When multiple operations are perfor ...

Oracle Global Temporary Table is hereinafter referred to as GTT (Global Temporary Table), and Private Temporary Table is hereinafter referred to as PTT (Private Temporary Table). The main differences between GTT and PTT are as follows: GTT is earlier. GTT is a feature of 8i and PTT is a feature of 18c.The data of GTT and PTT are session priva ...

The author's official account is welcome to exchange. In the process of MySQL master-slave replication, errors are inevitable due to various reasons. How to solve the errors in the replication process? This article will demonstrate how to skip the corresponding errors in the slave database when the master-slave inconsistency is caused by the ...