String splicing function of MySQL

MySQL String concatenation of has three functions

• CONCAT(str1,str2,…)
• CONCAT_WS(separator,str1,str2,…)
• GROUP_CONCAT(expr)

These three functions have their own functions , Now test to see what the effect looks like

Prepare data sheets

CREATE TABLE `user_info` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `age` int(3) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;

Prepare the data

id	name	age
1	Ana	24
2	Ame	24
3	Clid	27
4	Dave	27
5	Eva	27

test

CONCAT、CONCAT_WS In fact, it's almost , Namely CONCAT_WS You can set the separator by yourself , And these two fields are the data of the same row .

Use CONCAT

select CONCAT(name,age) as result from user_info

result

result
Ana27
Ame24
Clid24
Dave24
Eva24

Use CONCAT_WS

select CONCAT_WS(':',name,age) as result from user_info

result

result
Ana:27
Ame:24
Clid:24
Dave:24
Eva:24

Use GROUP_CONCAT, This can aggregate multiple lines into one line , Also more commonly used

select GROUP_CONCAT(name) as result from user_info

result

result
Ana,Ame,Clid,Dave,Eva

You can also group and aggregate

select GROUP_CONCAT(name) as result,age from user_info GROUP BY age

result

result 							age
Ame,Clid,Dave,Eva				24
Ana								27

These three functions are commonly used , But I just briefly demonstrate this function , In depth, you can check other information .