Question

I am trying to calculate the median from a table with various types of data mixed together (I can’t modify the table). Rows 3 and 6 are examples of this data mixed in, and rows 1, 2, 4, and 5 are examples of rows which I legitimately need the data from (WHERE form_id = 1 AND field_id = 1):

id    form_id    field_id    value
1     1          1           200
2     1          1           290
3     1          2           'Delicious Bacon'
4     1          1           320
5     1          1           120
6     2          3           9000000

I understand that I can derive median from a table using the following:

SELECT x.value from form_data x, form_data y
GROUP BY x.value
HAVING SUM(SIGN(1-SIGN(y.value-x.value))) = (COUNT(*)+1)/2;

However, the data mixed in challenges my SQL abilities. How can I find the median of this data, only where form_id = 1 and field_id = 1?

Answer 1

Try this

SELECT x.value from form_data x, form_data y
WHERE x.form_id=1 and x.field_id=1 and y.form_id=and y.field_id=1
GROUP BY x.value
HAVING SUM(SIGN(1-SIGN(y.value-x.value))) = (COUNT(*)+1)/2;