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Today's release of this may be the most careless one of their own, a lot of problems want to understand, but when doing it, they found that not as they imagined, but also slowly debugging, on-line check a lot of methods are always not working, or their own grope out! Front end display + verification + background query, ...

Hibernate's addition, deletion, modification and query increase There are many ways to add, such as save, persist, savaoroupdate and merge. The use method is as follows. The code here follows the previous section package test; import java.util.Date; import org.hibernate.Session; import org.hibernate.SessionFactory ...

CentOS 6.5 192.168.1.84 host CentOS 6.5 192.168.1.83 slave 1, Primary server configuration: Create synchronization user and specify server address [root@node04 ~]# mysql -u root -p111111 mysql>use mysql; mysql>grant replication slave on *.* to 'tongbu'@'192.168.1.84' identified by '123456'; mysql>flush privileges # ...

Not finished yet... To be edited To ensure that there is no other parameter configuration impact, a CentOS7 virtual machine with minimized installation is reinstalled 1. Install mysql5.6 database https://my.oschina.net/sgmder/blog/1631045 2. Configure mysql, enable binlog, and change binlog mode to Row Level mode vi /etc/my.cnf  Modify the ...

Preface The call of System.currentTimeMillis() takes more time than a normal object of new (I don't know how much more time it takes, but I heard it's about 100 times). However, this method is also a common method, sometimes it has to be used, such as generating wokerId, printing logs, etc. there must be performance problems in the high and emo ...

Source: https://www.cnblogs.com/izecsonLee/p/9058385.html The most recent requirement is to output the log of a certain class to the specified file. Generally, it is output to the corresponding file according to the log level. Refer to related materials and logback tutorial, write the following demo for reference.   1. Add an appender ...

The predicate in Cocoa provides a general query method to process data, The filtering form of data can be obtained and specified. In the actual development of Cocoa, NSPredicate and its parent classes NSComparisonPredicate and nscompoundpredict can be used. Its style is similar to the mixture of SQL query language and regular expression, provid ...

Sometimes we need to create indexes for some partitions. Oracle 11g provides this function. You can create local and global indexes on partial partitions. Global partial index: only those partitions that need to be indexed will be indexed, and other partitions will not be created. Local index: if index is turned on fo ...

MySQL GROUP BY statement The GROUP BY statement groups the result set based on one or more columns. We can use COUNT, SUM, AVG, and other functions on grouped columns. GROUP BY syntax SELECT column_name, function(column_name) FROM table_name WHERE column_name operator value GROUP BY column_name; Example demonstration T ...

Due to the loss of control file caused by a power failure, the startup database reported ORA-00205 error: SQL> startup ORACLE instance started. Total System Global Area 419430400 bytes Fixed Size 2925120 bytes Variable Size 285216192 bytes Database Buffers 125829120 bytes Redo Buffers ...