Mysql运行计数在另一个查询中是否不同？

Question

I have a mysql query that returns an array of rows. I need to get a count of distinct values from one column. My query is dynamic, where multiple conditions evaluated by php change the WHERE clause, so I really want to do it all inside one query if possible to avoid duplicating every single dynamic condition.

Here is a simple version of what I would like to do --

If this represents a very simple version of my sql table:

Column1, Column2, Column3, Group, Active
   a   ,    b   ,    c   ,   1  ,  YES
   d   ,    e   ,    f,  ,   2  ,  YES
   g   ,    h   ,    i   ,   1  ,  YES
   j   ,    k   ,    l   ,   3  ,  NO

I would like to do something like this:

"SELECT Column1, Column2, Column3, Group,
(SELECT COUNT(DISTINCT Group) FROM 'table') AS totalGroups
 FROM 'table'
WHERE Active like 'YES';"

I want the result to be that I can report:

a) the total rows in the query

mysql_num_rows($result) should equal = 3

b) the total number of distinct groups

$phparray['totalgroups'] should equal = 2
(Right now, 'totalgroups' equals = 3)

(1) Can this be done? Currently, 'totalgroups' returns 3 instead of two. Can I get it to use the same "Where" clause as the rest of the query?

In my actual code, which is much more complex, my count is returning 1,945 when I'm only wanting it to return 2. :)

(2) Is there a better way to do it?

I tried php's array_unique() and array_count_values() , but array_unique() does not work on multidimensional arrays, and I couldn't get array_count_values() to work correctly.

I looked at many other questions, but couldn't find one where someone was asking this particular question. I reviewed the MYSQL manual RE subqueries, but it didn't address whether you could share the Where clause.

If you must have my actual code in order to answer this question (instead of the demo representation above), please let me know. It's over two pages with all the php dynamic qualifiers, so I decided to write demo code for clarity's sake.

Answer 1

Are you trying to get a list of all the records on the table, along with on every line a count of the number of active rows and a count of the unique active groups?

If so then something like this:-

SELECT Column1, Column2, Column3, Group, ActiveDistinctGroups.ActiveCnt, ActiveGroups.ActiveCnt
FROM 'table' a
CROSS JOIN (SELECT COUNT(DISTINCT Group) AS ActiveCnt FROM 'table' WHERE Active like 'YES') AS ActiveDistinctGroups
CROSS JOIN (SELECT COUNT(Group) AS ActiveCnt FROM 'table' WHERE Active like 'YES') AS ActiveGroups
WHERE Active like 'YES'

If you really need to avoid the extra WHERE clauses:-

SELECT Column1, Column2, Column3, Group, ActiveDistinctGroups.ActiveCnt, ActiveGroups.ActiveCnt
FROM 'table' a
INNER JOIN (SELECT Active, COUNT(DISTINCT Group) AS ActiveCnt FROM 'table' GROUP BY Active) AS ActiveDistinctGroups ON a.Active = ActiveDistinctGroups.Active
INNER JOIN (SELECT ActiveCOUNT(Group) AS ActiveCnt FROM 'table' GROUP BY Active) AS ActiveGroups ON a.Active = ActiveGroups.Active
WHERE a.Active like 'YES'