Mysql String concatenation is the same as append

Values (mail_url,. com) whereid169; To be continued, if you have any related information, please add the stored procedure: createPROCEDUREdowhile () BEGINDECLAREiintDEFAULT0; STARTTRANSACTION; values (MAIL_url) values (***

Update table set mail_url = CONCAT (mail_url ,. com) where id = 169; To be continued, if you have any related information, please add the stored PROCEDURE: create PROCEDURE dowhile () begin declare I int DEFAULT 0; START TRANSACTION; WHILE i10 DO insert into TABLE (MAIL_url) values ('***

Update table set mail_url = CONCAT (mail_url, ". com") where id = 169;

To be continued, if you have any questions, please add them.

Stored Procedure:

Create PROCEDURE dowhile () begin declare I int DEFAULT 0; start transaction; WHILE I <10 DO insert into TABLE (MAIL_url) values ('*******'); set I = I + 1; END WHILE; COMMIT; END

Call the above Stored Procedure Method: [call dowhile;] possible causes of error:

[Err] 1062-Duplicate entry ''for key 2

Check whether the unique constraint is set for your field. The preceding error indicates that the unique constraint is violated.