Programmer Help

demand The project team receives a requirement to compare what COBOL statement writes with the data dictionary of the company, then form a standard SQL statement, and then compare with the data table structure of our project team to find out the difference. 1.COBOL statement **************************************************************** ...

1. JPA Core API Objects 1.1.Persistence persisted object Persisitence is primarily used to create an EntityMangerFactory, which can create a corresponding EntityMangerFactory based on the persistence unit name passed in. // Corresponding profile persistence-unit name="cn.yif.jpa02" // Create an entity class management factory by persisti ...

1, Refactoring simple CRUD 1.JDBC tool class 1. Because there are some same codes in crud, we can extract them and refactor them into tool classes. 2. Set the tool class to static static static class, which is convenient to call and does not need new object. 1 public class JDBCUtil { 2 private static String driver = "com.mysql.jdbc.Drive ...

rman uses level 0 backup set for different recovery $ rman target / /* It is used for testing. It is found that the test fails. It is very useful if you need to restore spfile There is no parameter file. An instance of DUMMY will be generated under the command of RMAN RMAN> set dbid=1234567890; */ Start datab ...

Previously, we have talked about how to judge the sql type by Mycat, and then perform different processing for different types of sql[ Analysis of Mycat principle processing of SQL statement ]Now, let's take a look at the explain statement and how Mycat handles it. The EXPLAIN statement provided by Mycat is not used to ...

Configuration and use case of c3p0 Test class package com.serendipity.c3p0; import java.sql.Connection; import java.util.List; import org.apache.commons.dbutils.QueryRunner; import org.apache.commons.dbutils.handlers.BeanListHandler; import org.junit.Test; import com.mchange.v2.c3p0.ComboPooledDataSource; import com.serendipity.dbutils. ...

There are so many explanations on the combination index on the Internet on the leftmost principle: I feel that 99% of them are nonsense, and I don't know that I'm talking about a jb after reading it So write it here! Principle: can the sql you use use use composite index? Conclusion: the combination index you set up (a,b,c,d) no matter how yo ...

ansbile installation: # ansible needs to install epel warehouse in CentOS7 yum install -y epel-release yum install -y ansible There are several ways to install. yum installation is the simplest. Installing ansible is not the key. My version is as follows: [root@szwpldb1081 mysqltools]# ansible --version ansible 2.7.10 config file = /etc/an ...

1 usage of transaction 1 Bank transfer cases-Do not use transactions: @Test public void testTX1() throws Exception { Connection conn = JdbcUtil.INSTANCE.getConn(); //1.Find out whether Zhang Wuji's account balance is greater than or equal to1000block String sql = "SELECT * FROM account WHERE ...

There are seven steps for JDBC connection: 1 load database driver Class.forName("com.mysql.jdbc.Driver") 2 provide the url of jdbc connection 3. Create a database connection. Use drivermanager.getconnect (String URL, String username, String password ) 4 create a statement • to execute SQL statements, you must obtain a java ...