[英]how to I create a derived column by aggregate data from another column in another table
[英]How can I check the validity of a column elements in MySQL that were derived from another column of the same table?
例如,如果我在一列中有 Project_ID = 123456 并且 Project_Name = R123456。 我想检查 Project_Name 是否在每个元素中都正确输入了前缀 R。 我可以使用什么查询?
select Project_ID,
case when Project_Name = concat('R', Project_ID)
then 'ok'
else 'fail'
end as result
from your_table
或仅获取不正确的:
select Project_ID
from your_table
where Project_Name <> concat('R', Project_ID)
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