This time, we introduce two useful functions: time series complement function and abnormal contrast function.
1. Time Series Complement Point Function
Indicator description in the chart above
Log Event Event T0: The earliest event a log generates
Log Event Event T1: The latest event the log generates
Actual point data: There is definite data ...
Added by puritania on Mon, 20 Apr 2020 06:44:07 +0300
EFCore Extended Select Method (Customize Query Statements to Entities)
Often when working with databases, queries return fields that are inconsistent with what we define as entities, so it is cumbersome to create a large number of models for UI or interface layers and to manually correspond to the fields.This article addresses these repeti ...
Added by welsh_sponger on Fri, 17 Apr 2020 20:51:39 +0300
SELECT ID,NAME,DECODE(LEVER,1,'professor',2,'associate professor',3,'tutor','lecturer') POSITION,
(SELECT CLASSNUM FROM CLASS T WHERE T.NUM = S.NUM) NUM FROM TEACHER S WHERE T.LEVER IN (1,2,3);
The usage logic of the decode function in the previous SQL is as follows:
RETURN 'professor'(Translati ...
Added by msimoes on Thu, 16 Apr 2020 18:34:45 +0300
1. Relational and non-relational databasesRelational DatabaseA relational database is a structured database, built on a relational model and generally oriented to recordsHe works with data in databases using mathematical concepts and methods such as set algebraRelational models refer to two-dimensional table models, so a relational database is ...
Added by adiwood on Fri, 10 Apr 2020 04:16:00 +0300
Sometimes, a select statement contains multiple window functions whose window definitions (OVER clauses) may be the same or different.
For the same windows, there is no need to partition and sort them again. We can merge them into a Window operator.
such as The realization principle of window function in spark and hive Case in:
select i ...
Added by serverman on Tue, 07 Apr 2020 17:52:21 +0300
es version at least 6.1 above
"format": "yyyy-MM-d ...
Added by ryanlwh on Mon, 06 Apr 2020 20:42:41 +0300
Requirement: the exchange code of excel is imported into mysql, with a total of 30W pieces of data. Navicat has its own functions. It can directly import excel data into mysql. There are too many databases and manual operation is very troublesome. A script is written with python.
Use pip to import xlrd,pymysql library. ...
Added by uncleronin on Mon, 06 Apr 2020 19:22:11 +0300
As a part of ETL, sometimes you need to generate the Insert script of the data, and then copy the human flesh to another place for execution.
Students who are familiar with SMSS all know that there is a task of generating scripts, which can generate database create scripts, and in fact can also produce data in tables.
Automatic ETL can't even e ...
Added by michalchojno on Mon, 06 Apr 2020 17:33:04 +0300
_Copyright Statement: This is an original article created by a blogger and may not be reproduced without the permission of the blogger.
SQL Server series software is a relational database management system introduced by Microsoft.At a conference in San Francisco on April 16, 2014, Microsoft CEO Satia Nadela officially launched "SQL Ser ...
Added by blade_922 on Sun, 05 Apr 2020 08:45:43 +0300
JDBC(Java Database Connectivity)
Java database connection specification (a set of interfaces) provided by Sun company
JDBC core class
DriverManager create connection
Connection connection class
Statement execute sql statement
ResultSet result set
JDBC connection steps
1. Registration driver
Added by thinguy on Sat, 04 Apr 2020 18:04:51 +0300