MySQL concat concat_ws group_concat function (connection string)

CONCAT (str1,str2,...)   NULL.

Mysql> SelectConcat' One',' A',' -');+------------------------+|Concat' One',' A',' -')|+------------------------+| 112233 |+------------------------+

Mysql> SelectConcat_ws (',',' One',' A',' -');+-------------------------------+|Concat_ws (',',' One',' A',' -')|+-------------------------------+|  One, A, - |+-------------------------------+

Group_concat ([DISTINCT]The field to connect to[ORDER by Asc/desc sort field] [Separator ' delimiter ']) basic query MySQL> Select *  fromAA;+------+------+|Id|Name|+------+------+|1 | Ten||1 |  -||1 |  -||2 |  -||3 |  $   ||3 |  -   |+------+------+6Rowsinch Set(0.00sec) Group by ID, print the value of the Name field on one line, comma separated (default) MySQL> SelectId,group_concat (name) fromAaGroup  byID;+------+--------------------+|Id|Group_concat (name)|+------+--------------------+|1 | Ten, -, -||2 |  - ||3 |  $, -|+------+--------------------+

GROUP by ID, print the value of the Name field in one line, comma-delimited, and reverse-order in the name column MySQL> SelectId,group_concat (nameOrder  byNamedesc) fromAaGroup  byID;+------+---------------------------------------+|Id|Group_concat (nameOrder  byNamedesc)|+------+---------------------------------------+|1 |  -, -,Ten   ||2 |  -||3 |  -, $|+------+---------------------------------------+

GROUP by ID, print the value of the Remove redundant name field in one line, comma separated MySQL> SelectId,group_concat (distinctName fromAaGroup  byID;+------+-----------------------------+|Id|Group_concat (distinctName|+------+-----------------------------+|1 | Ten, -||2 |  -   ||3 |  $, - |+------+-----------------------------+

MySQL concat concat_ws group_concat function (connection string)