SQL performance is always a key issue that every DBA faces. This article introduces five ways for improving SQL performance. If subquery is a parameter, then use EXISTS instead IN If you use subquery as a parameter, it is better that you us EXISTS than IN even these two statements return same result, the […]
When you run docker under the condition of Linux Container (Windows 10 Home edition), you can find the location of those by typing docker info command in power shell bash. The image shown above shows that docker image are stored in /var/lib/docker path. The real thing is that you can’t find anything in this path
Where are Docker images you have downloaded (Windows 10 Home Edition)? Read More »
Enum is a value type which can be byte, short, int and long. We can use enum to avoid the occurrence of magic number. For example: var season = dateSeason == 1 ? “Spring” : “other season” you might notice that when the project grows bigger, there will be more magic numbers you generate.
When you run a static website from nginx web server, you will sometimes see 403 Forbidden error message in the webpage. The reasons include web server permission, nevertheless the path can also be the cause as it actually does not exist. You have to create the path by yourself. This article aims to solve this
C# delegation works like C/C++ function pointer (type safe). We can use delegation as the parameter of a method and pass them between methods. This helps the programmer to follow one of SOLID principles – OCP. By using delegation, we don’t have to write long and tedious if-else or switch statements. The example of using
When you are familiar with CASE, you can make your SQL statement more flexible and reduce redundant semantics. CASE can be categorized into two cases. One is simple case CASE WHEN condition THEN result [WHEN···] [ELSE result] END; and the other one is searched case CASE expression WHEN value THEN result [WHEN···] [ELSE
This article introduces one of solid principles which is ISP (Interface Segregation Principle). It is better to build a small-sized interface than a heavy interface as a small-size interface is easier to refactor and decouple. Too many is better than too few For example, you have IAnimal interface which has three methods(eat, move and sleep)
This article will introduce one of solid principles DIP which is the abbreviation of Dependency Inversion Principle. High level modules should not depend upon low level modules. Both should depend upon abstractions. Abstractions should not depend upon details. Details should depend upon abstractions Interpretation: Use abstraction rather than concrete object Example: Say you go to