MySQL two trick to handle strings: Substring_index,concat

MySQL two trick to handle strings: Substring_index,concat

I've been dealing with strings in the database lately, and we've found that they're used to go with these two functions:

　　1, Substring_index (Str,delim,count)

　　STR: The string to be processed

　　Delim: Delimiter

　　Count: Count

Example: str=

Substring_index (str, '. ', 1)

The result is: www

Substring_index (str, '. ', 2)

The result is: Www.google

That is, if Count is a positive number, then it is the left-to-right, and the left of the nth delimiter.

Conversely, if it is a negative number, it is all the content from the right to the right of the nth delimiter, such as:

Substring_index (str, '. ',-2)

The result is: google.com

Someone will do for, if I ah in the middle of Google what to do?

Very simple, two directions:

1, from the right of the second delimiter to the right of all, and then the left number of the first delimiter left:

Substring_index (Substring_index (str, '. ',-2), '. ', 1);

2, you know!

　　2,concat is a couple of strings that can be multiple oh.

Concat (' wo ', ' lin ', ' Xue ', ' bin ')

The result is wolinxuebin.

MySQL two trick to handle strings: Substring_index,concat