如何选择12个月以上的数据？

Question

I have a table as follows;

caravan_id, description, date_purchased, special_instructions, health&safety_check, notes

health&safety_check is a date field.

How can I perform an SQL query for data in this table that returns all rows which have a health&safety_check older than 12 months. But if possible one that is based on 12 months, not on today's date such as < 10/12/2011

Answer 1

Something like:

select *
from t
where add_months("health&safety_check", 12) < sysdate

I assume you don't want to hardcode the current date but are happy with using a variable for it.

Jeff, in the comments, makes a good point (although, in Oracle, you can create an index on a function so you can get around the problem). This is easily fixed:

where "health&safety_check" <add_months(sysdate, -12)

Answer 2

select *
from t
where "health&safety_check" < add_months(sysdate, -12)

Answer 3

You can use this query:

SELECT *
FROM table_name
WHERE `health&safety_check` < ADDDATE(NOW(), INTERVAL -12 MONTH)

ADDDATE(NOW(), INTERVAL -12 MONTH) mean this date minus 12 Month, you can use other date field or variable to change NOW().

NOW() mean today.