SEARCH KEYWORD -- QUERY PARAMETERS


  <=> operator in MySQL

Have you ever seen "<=>" in a SQL query while using MySQL? Does it mean less and equals to and greater than? Actually if you consider it as the union of <= and =>, great, you are close to it. This is one form of equal operator in MySQL, it has the similar meaning to the = operator with some subtle difference. According to MySQL documentation, <=> is NULL-safe equal. This operator performs an equality comparison like the = operator, but returns 1 rather than NULL if both operand...

   MySQL,NULL safe,<=>     2014-03-24 06:23:22

  A simple tutorial on GoLang connecting to Clickhouse

Go, also known as Golang, is a statically-typed, concurrent programming language created by Google. ClickHouse is a high-performance, column-oriented database management system that can be used for real-time data analysis. This tutorial will provide a deep dive into how to connect to ClickHouse from a Go program, including how to perform common database operations such as SELECT and INSERT statements. Before proceeding, it is assumed that you already have Go and ClickHouse installed on your mach...

   GOLANG,CLICKHOUSE,TUTORIAL     2023-02-11 07:05:36

  OpenLDAP Proxy -- Introduction

OpenLDAP is an open source project which is intended to provide some commercial-grade, fully featured applications and development tools based on the well known Light-weight Directory Access Protocol(LDAP). Hence corporations which want to manage their user and group information can freely use these tools.  OpenLDAP provides ldap servers, ldap clients and corresponding tools to work on LDAP. The LDAP server is called slapd(Stand-alone LDAP  daemon). And it would serve as the server whi...

   META,OPENLDAP,OPENLDAP PROXY,SLAPD,SLAPD.CONF,LDAP     2017-10-28 11:20:00

  Check mobile device using JavaScript

Sometimes developers want to know whether the user is using a mobile browser or a desktop browser so that they can build corresponding user experience. Although in many cases responsive web design would help solve component alignment issues, there are performance related considerations in some cases where some code should not be ran or some feature should not be available if user is on mobile browser. or vice versa This post will summarize a few ways which are commonly used to check whether a us...

   CHECK,MOBILE BROWSER,MOBILE DEVICE,JAVASCRIPT     2021-10-02 01:36:16

  Name resolution order in JavaScript

To understand what value a variable has in JavaScript, we need to understand some concepts such as scope and name resolution order. JavaScript has two scopes; one is program level and the other one is function level. Unlike in C,C++ or Java, JavaScript has no block level scope. So a variable defined in a if block will still be available outside. For example, the below example: var foo = 1; function bar() { if (true) { var foo = 10; } alert(foo); } bar(); The alert will display 10 since the ...

   JavaScript,Scope,Name resolution     2013-07-10 01:29:28

  A guide on installing and running Clickhouse on macOS

ClickHouse is a high-performance open-source columnar database management system developed by Yandex. Here are some of the key features of ClickHouse: Columnar storage: ClickHouse uses a columnar storage format, which allows it to efficiently store and retrieve data by column, rather than by row. This results in much faster query performance, especially for analytical and aggregate queries. Real-time data processing: ClickHouse is designed to handle real-time data processing and can handle bill...

   CLICKHOUSE,MACOS     2023-02-15 06:04:55

  GoLang to build smaller executable file

Normally the executable file built with go is a bit large, it is always desired that a smaller executable file should be generated though. In this post, a couple of ways to reduce the size of the executable will be introduced. The end effect is that the executable file size would be much less than the normal generated one. The file which is built normally has below size. Mode LastWriteTime Length Name ---- ------------- ------ ---- -a---- 12/14...

   GOLANG,EXECUTABLE     2019-12-13 20:10:45

  Sites to go if you want to learn web development

Before you start to do web development, either for a hobby or for your start up project, you should be prepared for learning many different technologies including both front end and back end. You may need to deal with UI design, business logic design, data store and infrastructure setup etc. This seems a very complex. Indeed, if you know where you should go, the  it's actually not so hard. Here are some sites you should go when you face issues while you are doing web development. These site...

   Web development,Resource,Site     2013-09-19 08:12:23

  An alternative way to parse URL in JavaScript

Normally when we need to process URL in JavaScript, we may use the location object. Then we can use location.hostname,location.href,location.port etc to get the information we need. In this post, we will parse an URL with an alternative way. We can use an URL to create a DOM object by calling document.createElement("a"). The complete code is: function parseURL(url) { var a = document.createElement('a'); a.href = url; return { source: url, protocol: a.protocol.replace(':',''), host: a.ho...

   URL,location,parse     2014-03-03 07:05:11

  Use progressive JPEG to improve user experience

JPEG image files can have two different save types : Baseline JPEG and Progressive JPEG. Both of them have the same extension name but with different display effect. Baseline JPEG This type of JPEG files are scanned from top to bottom consecutively, each line of the image data will be saved sequentially. When opening this kind of images, data will be displayed with the save order line by line until all the data are read. If the image size is very large or network speed is very slow, the image wi...

   USER EXPERIENCE,PROGRESSIVE JPEG,BASELINE JPEG     2013-07-25 08:11:50

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