Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
336 views
in Technique[技术] by (71.8m points)

sql - Using the correct, or preferable, not equal operator in MySQL

Which of the two (semantically equivalent) ways is preferable to test for inequality?

  1. 'foo' != 'bar' (exclamation mark and equals sign)
  2. 'foo' <> 'bar' (less than and greater than chevron symbols together)

The MySQL documentation clearly indicates that there is no difference between them and yet some people seem to be attached to only doing it one way or the other. Maybe this is just another pointless vi vs. emacs debate but when other people are reading your code (and therefore your queries), it's useful to maintain some consistency.

<> looks a lot like <=> which is a very underused operator but could perhaps lead to confusion at a quick glance since the two are nearly opposite (except for the obvious NULL cases).

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

<> should be preferred, all things being equal, since it accords with the sql standard and is technically more portable...

!= is non-standard, but most db's implement it.

sql:2008 grammar:

<not equals operator> ::=
  <>

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...