MySQL concat () character join function

How to use:

Concat (STR1,STR2,...)

MySQL Tutorials > select concat (' 11 ', ' 22 ', ' 33 ');
+------------------------+
| Concat (' 11 ', ' 22 ', ' 33 ') |
+------------------------+
| 112233 |
+------------------------+

For more details please see: http://www.111cn.net/database/110/concat_concat_ws.htm

Returns a string resulting from a connection parameter. If any of the arguments are null, the return value is null

The following look at an update updated data, the use of the CONCAT function;
*/

$sql = "Update ' tablename ' Set Cityid=concat (Cityid, ' 000011 ') where length (Cityid) >18 and Cityid not like '%000000 11% ' ";

/*
Meaning:
If all parameters are non binary strings, the result is a non binary string.
If the argument contains any twos feed string, the result is a binary string.
A numeric parameter is converted to an equal binary string format