Create a model for an existing database in the Entity Framework Core
Here, you will learn how to create context and entity classes for existing databases in the Entity Framework Core. Creating entity and context classes for an existing database is called the database first method.
EF Core does not sup ...
Posted by UQKdk on Fri, 07 Feb 2020 06:08:09 -0800
The database can be operated easily by Java using JDBC API. In java8 and later, JDBC ODBC bridge connections have been dropped. For different databases, download the driver to the corresponding official website.
Here are three common database driver names, driver class and corresponding connection strin ...
Posted by spiceweasel on Fri, 07 Feb 2020 01:45:48 -0800
1. MySQL functions
Official website: https://dev.mysql.com/doc/refman/5.7/en/func-op-summary-ref.html
1.1. Common Functions
-- ==================== Common Functions =============================
-- Mathematical operations
SELECT ABS(-8) -- absolute value
SELECT CEILING(9.4) -- ceil
SELECT FLOOR(9. ...
Posted by undecided name 01 on Wed, 05 Feb 2020 20:01:33 -0800
MongoDB pipeline definition
The aggregation pipeline of MongoDB will pass the results of MongoDB documents to the next pipeline after one pipeline is processed. Pipeline operations are repeatable.
Common Aggregate pipeline operators of Aggregate in SpringBoot
Customize the collection userCollection and initialize the data structure
Store bean u ...
Posted by adnan856 on Wed, 05 Feb 2020 07:50:14 -0800
JDBC development steps
1. Registration driver
---Tell the JVM which database driver to use
2. Get connected
---Use the classes in JDBC to complete the connection to the MySQL database
3. Get statement execution platform
---Get the executor object of the SQL statement through the connection object ...
Posted by scross on Wed, 05 Feb 2020 06:10:11 -0800
Some operators and functions mentioned above can perform some time operations, but cannot obtain the current Processing Time or Watermark timestamp of the operator, which is simple to call but relatively limited in function. If you want to get the time stamp of Watermark in the data flow, or shuttle bac ...
Posted by eddjc on Wed, 05 Feb 2020 02:21:22 -0800
Java8 Chinese Documentation: http://www.matools.com/api/java8
java8 LocalDate Reference: https://www.journaldev.com/2800/java-8-date-localdate-localdatetime-instant
Background: Time sections are formatted where deadlines are involved, such as the start and end times of events (2019-11:00:00~2019-11 ...
Posted by Altairzq on Tue, 04 Feb 2020 19:27:29 -0800
Cursors can be very useful sometimes. When updating a small part of data, they can easily update the data. There is no need to write another small tool to do this, just write SQL directly
Here is a practical example:
-- Declare field variables
DECLARE @RegionCode INT;
DECLARE @RegionName NVARCHAR(64);
DECLARE @ProvinceId INT;
-- d ...
Posted by shock on Tue, 04 Feb 2020 10:02:03 -0800
Count: used to find the number of data.
The model used in all of the following examples is:
from django.db import models
# Define author model
name = models.CharField(max_length=100, unique=True)
age = models.IntegerField()
email = models.EmailField()
Posted by digitalalpha on Mon, 03 Feb 2020 05:59:44 -0800
This topic is similar to some of the search topics in Leetcode.
The problem you want to deal with is: count the number of two adjacent digits of a word. If there are w1,w2,w3,w4,w5,w6, then:
The final output is (word,neighbor,frequency).
We implement it in five ways:
Spark SQL method
Spark SQL for Scala
Posted by olechka on Sun, 02 Feb 2020 08:18:59 -0800