Tag：Sentence
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Time：2021-3-4
mybatis- config.xml Core profile mybatis- config.xml The contents are as follows Configuration Properties Settings Typealiases (type aliases) Typehandlers (type processors) Objectfactory (object factory) Plugins (plug-ins) Environments (environment configuration) Environment (environment variable) Transaction manager Datasource (data source) Databaseidprovider (database vendor identification) Mappers (mapper) Pay attention to the order of element nodes! Wrong sequence will be reported […]
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Time：2021-3-4
background Developers in the development of various needs, the structure of the database and data changes, each time the development is completed, online will synchronize the database structure & data, so need to find out the need to synchronize the database DDL and DML statements, less change is OK. Once the data changes involve many […]
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Time：2021-3-3
[20200211] using DBMS_ SHARED_ POOL.MARKHOT And SQL_ Calculation of id.txt –//Previously written, using DBMS_ SHARED_ POOL.MARKHOT Tag hot SQL_ ID, so the same SQL statement uses different SQL_ id.–//Link: http://blog.itpub.net/267265/viewspace-2147197/ =>[20171110] same SQL statement_ Can Id be different–//I’m curious to know how Oracle calculates SQL in this case_ It’s not. –//Correction: SQL statement uses DBMS_ […]
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Time：2021-3-3
Distinguish exception from syntax error When writing Python programs, errors are often reported. There are usually two kinds of errors: Syntax error:Some grammatical errors are exceptions Exception syntax error Syntax error, also known as parsing error, is one of the most common errors In [1]: while True print(‘Hello!’) File “<ipython-input-1-5c66e4fd0ae9>”, line 1 while True print(‘Hello!’) […]
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Time：2021-3-2
MS SQL Server / MySQL / Oracle log extraction and security analysis 1、 MS SQL Server Log Analysis: 1. Introduction to MS SQL Server database: Microsoft SQL server is a relational database management system (RDBMS) developed by Microsoft. It has the advantages of easy to use, good scalability and high degree of integration with related […]
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Time：2021-3-2
Environmental Science:Centos7.4 oracle11.2.0.4 (building RAC cluster) Problem Description:When using exp command to export, some tables prompt “exp-00003: storage definition of segment (0,0) not found” warning. Cause of the problem:This problem is caused by the exported data table is empty. Oracle 11gr2 does not allocate segments to save space when there is no data in the […]
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Time：2021-3-1
1. MySQL performance loss caused by a single quote It’s hard to avoid some disappointments in life. Some come from ourselves, but some are not. Today’s winter solstice is the shortest day and the longest night in the northern hemisphere. Today, let’s share the huge difference between adding single quotation marks and not adding single […]
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Time：2021-3-1
preface Many people may have been using mybatis all the time, but the SQL execution process of mybatis may not be clear to everyone. Now that you have come in, read through this article and you will get the following: 1. How to bind mapper interface and mapping file 2. Execution flow of SQL statement […]
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Time：2021-2-27
1. Limit statementPaging query is one of the most commonly used scenarios, but it is also the most prone to problems. For example, for the following simple statements, the general idea of DBA is to type, name, create_ Add a composite index to the time field. In this way, conditional sorting can effectively use the […]
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Time：2021-2-27
Because this project does not use framework, it uses SQLite database. You can imagine how much splicing SQL will be used in the later business, which will be quite troublesome. Once the database changes, a lot of things will have to be changed. So the basic is to encapsulate and generate SQL. Reflection and custom […]
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Time：2021-2-27
Many times, we need to pass in multiple parameters to the SQL statement, but if these parameters are not an object as a whole, what should we do? Here are two solutions for reference only. 1. Encapsulate multiple parameters into a map To test the interface, we pass in a map where value is an […]
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Time：2021-2-27
Additional functions of “local characteristics” Due to historical factors, Django brought his owndjango.contrib.localflavor–A variety of code snippets that can be used in a particular country, region, or culture. To facilitate maintenance and reduce the size of the Django code base, the code is now released separately from Django. See the official document for details: https://django-localflavor.readthedocs.org/ […]
