MySQL 5.7

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select locate('XXX', 'Hello XXX tomorrow we XXX will meeting in XXX Dubai, Do you want join us XXX')


locate('XXX', 'Hello XXX tomorrow we XXX will meeting in XXX Dubai, Do you want join us XXX')


7


create table wp_comments(comment_id int, comment_content varchar(200));
insert into wp_comments values (334, 'Hello XXX tomorrow we XXX will meeting in XXX Dubai, Do you want join us XXX ?'); )
update wp_comments
set comment_content = concat(
    substr(comment_content, 1, locate('XXX', comment_content) - 1),
    'MMM',
    substr(comment_content, locate('XXX', comment_content) + 3)
) 
where comment_id = 334 and locate('XXX', comment_content) > 0
select * from wp_comments where comment_id = 334;


comment_id
comment_content


334
Hello MMM tomorrow we XXX will meeting in XXX Dubai, Do you want join us XXX ?