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This article starts with WeChat public's "Android development tour". Welcome to pay more attention to get more dry goods. Room is a member of Jetpack component library, belonging to ORM library. It mainly makes a layer of abstraction for Sqlite, so as to simplify the operation of database by developers. Room supports syntax checking a ...

mysql database can be opened in the security mode, but by default, the security mode is not opened. What is the security mode of mysql Do not know whether the partners have maintained the database table business data, or because the program bug leads to the update of the entire table, and the painful experience of the whole table deletion, the ...

Recently, druid monitoring is needed for maintenance of old projects, but druid is at least compatible with hibernate 4. There is no way to do this. You can do it by yourself. Based on com.alibaba.druid.support.hibernate.DruidConnectionProvider, the ConnectionProvider interface is implemented To use the druid data source, make the following c ...

The nature of data reading and writing No matter which ORM framework, the essence of data reading and writing is to encapsulate JDBC. Its main purpose is to simplify the development process of JDBC, so that developers pay more attention to business. The following is the core process of JDBC: Register JDBC driver (Class.forName("XXX") ...

The cause of stack overflow Before solving the stack overflow problem, we first need to know the causes of stack overflow, which are mainly as follows: Whether there is recursive call or not, cyclic dependent call Is there a large number of cycles or dead cycles Too many global variables Local variables are too large, such as array, List, Map ...

Runnable interface Runnable is an interface. There are only run methods in it. Thread also implements runnable interface, so to realize multithreading, you need to realize runnable interface finally, not to mention to directly demonstrate the code. Runnable test code public class RunnableDemo { public static void main(String[] args) { ...

Index and view details of Mysql database The concept of index The index of a database is similar to that of a BookIn a book, you can quickly find the required information by using the catalog without reading the whole bookThe table of contents in the book is a list of words with page numbers containing each wordDatabase indexIn the database, ...

Provide an interface package com.ming.MyBatis; import com.ming.MyBatis.POJO.Role; import com.ming.MyBatis.POJO.Student; import com.ming.MyBatis.POJO.StudentCard; import org.apache.ibatis.annotations.Param; import java.util.List; import java.util.Map; public interface RoleMapper { /** * @param id * @return */ public Rol ...

Migration database is often encountered in work.If you use phpmyadmin to import, you can solve the problem if the database is too small. If it is too large, it will be troublesome. Either it will time out or the file is too large to import.So I chose to use Navicat For Mysql to copy the database In this process, I often encounter a problem: ERR ...

Record a series of errors after modifying the size of sga once After modifying the sga size of oracle, we encountered a series of errors. 00844 and 00851 error reporting SQL> startup; ORA-00844: Parameter not taking MEMORY_TARGET into account ORA-00851: SGA_MAX_SIZE 2147483648 cannot be set to more than MEM SQL> 01078 error reporting SQ ...