如何将 select 文本列的一部分作为 mysql 查询中的新列

Question

I have a text column that save a json string on it. I want to select specific element of json as new column and i do not want to change type of this column to json. Is it possible? How can i do that?

My table name is 'logs' and my column name is 'response' and my target element in JSON string is 'server_response_time'.

Answer 1

If you have a valid JSON string stored in a string column, you can directly use JSON functions on it. MySQL will happily convert it to JSON under the hood.

So:

with t as (select  '{"foo": "bar", "baz": "zoo"}' col)
select col, col ->> '$.foo' as foo
from t

If your string is not valid JSON, this generates a runtime error. This is one of the reasons why I would still recommend storing your data as JSON rather than string: that way, data integrity is enforced at the time when your data is stored, rather than delayed until it is read.