mysql - 正确的代码改进

Question

有人可以看看我的代码吗，因为我不知道它在 MySQL 中是否可以

set @max=concat('select max(length(CommentsId))from', table_name);
    prepare stmt from @max;
    execute stmt;

    set @max=concat('UPDATE', table_name, 'SET CommentsId= ',CommentsId * power(10, (@max - length(CommentsId))),' WHERE CommentsId= ', @CommentsId );
    prepare stmt from @max;
    execute stmt;

Answer 1

from在,UPDATE和SET关键字之前或之后需要空格。

set @max=concat('select max(length(CommentsId)) from ', table_name);
prepare stmt from @max;
execute stmt;

set @max=concat('UPDATE ', table_name, ' SET CommentsId= ',CommentsId * power(10, (@max -   length(CommentsId))),' WHERE CommentsId= ', @CommentsId );
prepare stmt from @max;
execute stmt;