过滤在mysql中存储为varchar的日期

Question

I am working with a MySQL database where dates are stored as varchar like this:

'2013-01-31' in column cl_223

I need to select only records from 2013 so I tried:

SELECT ..
FROM ....

Where cl_223 Like '2013'   

But that does not seem to work.

Thanks for all help!

Answer 1

You must add % as a wildcard :

SELECT ..
FROM ....

WHERE cl_223 LIKE '2013%'   

Answer 2

Storing a datettime value in a varchar column complicates some functionality on date time operations. But of course you can select your values writing such a query as follow

SELECT * FROM table_name WHERE cl_223 LIKE '2013%'

But if you don't have any performance issue you can convert the varchar column to a datetime value and write stronger typed query like this:

  SELECT * FROM table_name WHERE  STR_TO_DATE(cl_223,'%Y-%m-%d2') BETWEEN '2013-01-01' AND '2013-12-31'

But if you need a date time value as a date time in your process you'd better store it in a datetime column instead of a varchar column.

Answer 3

The query should be

SELECT ..
FROM ....

Where cl_223 Like '2013%'

However, the better solution would be to store the dates as DATE data types. If the dates in that column are always used in the format they're in now, the change would be backwards compatible. It would also allow for easier processing of the date values.