MySQL string connection function CONCAT () and Concat_ws ()

From the database to take n fields, and then combined together with the "," split display, at first thought with CONCAT () to deal with, good is the trouble, did not expect in the manual actually mentioned Concat_ws (), very useful.

Concat_ws (separator, str1, str2,...)

It is a special form of CONCAT (). The delimiter between the remaining parameters of the first parameter. The delimiter can be the same string as the remaining parameter. If the delimiter is null, the return value will also be null. This function skips any null and empty strings after the delimiter parameter. The delimiter is added between the concatenated strings

A simple example is as follows:

mysql> SELECT concat_ws (",", "First Name", "Second name", "Last Name"), ' first name,second name,last name ' Mys Ql> Select Concat_ws (",", "First name", NULL, "last Name"); ' First name,last name '

In addition, the following information is found on the Internet:

The MySQL CONCAT () function is used to concatenate multiple strings into a single string, one of the most important MySQL functions, and the MySQL CONCAT () function is described in detail below for your reference

MySQL CONCAT (str1,str2,...)

Returns the string that results from the connection parameter. If any one of the arguments is NULL, the return value is null. There may be one or more parameters. If all parameters are non-binary strings, the result is a non-binary string. If the argument contains any twos binary string, the result is a binary string. A numeric parameter is converted to the equivalent binary string format; To avoid this, you can use explicit type cast, for example: SELECT CONCAT (CAST (Int_col as CHAR), Char_col)

mysql> Select CONCAT (' My ', ' S ', ' QL '), ' MySQL ' mysql> select CONCAT (' My ', null, ' QL '); null mysql& Gt SELECT CONCAT (14.3); ' 14.3′

Another string connection function:

MySQL concat_ws (separator,str1,str2,...)

Concat_ws () represents CONCAT with Separator, which is a special form of the CONCAT (). The first parameter is the delimiter for the other parameter. The position of the delimiter is placed between the two strings to be concatenated. The delimiter can be a string, or it can be another parameter. If the delimiter is null, the result is null. The function ignores NULL values after any delimiter parameters.

mysql> SELECT concat_ws (', ', ' First name ', ' Second name ', ' last Name '); ' first name,second name,last name ' Mys ql> SELECT concat_ws (', ', ' First name ', NULL, ' last Name '); ' First name,last name '

MySQL Concat_ws () does not ignore any empty strings. (All NULL is ignored, however).

MySQL string connection function CONCAT () and Concat_ws ()