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Various methods of string splitting as mentioned above String splitting of row column conversion (solution aggregation) The results of performance test are as follows: The user-defined function is the fastest, 0.039s. If the data volume is large, adding concurrent will have more advantages; Simple SUBSTR method, follow ...

The return type of each query map of MyBatis is resultmap. However, when the return type property provided by us is resultType, MyBatis automatically assigns the corresponding value to the property of the object specified by resultType. When the return type provided by us is resultmap, it will data base The middle column data i ...

JDBC calls stored procedure Labels (space separated): jdbc Create an instance of the CallableStatement object through the prepareCall() method of the Connection object. When using the preparedCall() method of the Connection object, you need to pass in a String of type String indicating how to call the stored procedu ...

Reprinted from: https://blog.csdn.net/rpf2014/article/details/53116906 The last article introduced the operation of installation, addition, deletion, modification and query of FMDB This article is mainly about data query screening and common database statistical functions, which is convenient for later query and learni ...

Continue to summarize the work of Java background 2 Preface Previously, I wrote a SSM to replace c3p0 data source with Druid: https://blog.csdn.net/larger5/article/details/79509895 Recently, projects are basically based on SpringBoot. Similarly, using Druid as data source is also a very simple operation and principle Cod ...

The previous version is too simple. This version creates config, executor, handler, and mapped statement according to the source code format. The entire project structure is as follows: This project simulates several main categories of MyBatis: sqlsession, configuration, executor, mapperproxy, mappedstatement, result ...

1. Modify mybatis.properties #Master data source, default spring.datasource.driver-class-name=com.mysql.jdbc.Driver   spring.datasource.url=jdbc:mysql://127.0.0.1:3306/db   spring.datasource.username=root   spring.datasource.password=123456      #Initialization size, min, Max spring.datasource.initialSize=5   sprin ...

This article describes Python3's use of PyMySQL to connect to databases and implement simple add-delete checks.(Note python3) 1. Install PyMySQL PyMySQL is a library used to connect to MySQL servers in Python 3.x and mysqldb is used in Python 2.PyMySQL follows the Python database API v2.0 specification and includes t ...

Record some common and simple methods to avoid the bug problem of backtracking modification due to small details 1. It is possible that the value traversed by the array is null, We all know that when the field value of the database (such as mysql) is null, it will be transferred to the background of the program, and the compiler will automati ...

Transferring backup files across the public network is a job that operation and maintenance and DBA s often do. But the unencrypted compressed files are transferred on the public network, just like swimming naked in Yalong Bay. If you don't pay attention, you will be photographed. Ha ha! This paper mainly describes how to reali ...