There is such a requirement. In the Mysql database string field (permission), the user has multiple different mailboxes, which are separated by ','. Now we need to extract all the mailboxes of a certain mailbox. Member list.
Suppose there is a table:
CREATE TABLE users(id int(6) NOT NULL AUTO_INCREMENT,PRIMARY KEY (id),user_name VARCHAR(20) NOT NULL,emails VARCHAR(50) NOT NULL);
Initialize the table and add some records.
truncate table users
INSERT INTO users(user_name, emails) VALUES('小张','[email protected],[email protected],[email protected]');
INSERT INTO users(user_name, emails) VALUES('小王','[email protected],[email protected],[email protected]');
Some fields in Mysql are of string type. How to find records that contain certain characters?
Method 1
is very simple and can be implemented with %. For
example ,
SELECT * FROM users WHERE emails like "%[email protected]%";
but in this case, [email protected] will also be found, which does not meet the requirements.
Method 2
Use the mysql string function find_in_set();
SELECT * FROM users WHERE find_in_set('[email protected]', emails);
In this way, all users whose email field contains
[email protected] The effect we expected, the problem is solved!
It should be noted that the mysql string function find_in_set(str1, str2) function returns the position index of str1 in str2, and str2 must be separated by ",".