基于mysql条件的查询

Question

id  mem_id   tran_date  tran_type   tran_points plus_minus
-----------------------------------------------------------
 1    2     2011-10-19    test           50         +
 2    2     2011-10-19    test           50         +  
 3    3     2011-10-19    test           50         +
 4    2     2011-10-19    test           15         -

For every individual member all the values in tran_points needs to be added when data in plus_minus column = '+' and the sum of value in tran_points needs to be substracted when data in plus_minus = '-'

I want to have the following output :

member_id   points_balance
--------------------------
   2            85
   3            50

Answer 1

You can do this with a SUM(IF()) type of clause as follows;

SELECT mem_id AS member_id, 
    SUM( IF(plus_minus="+", tran_type, (0 - tran_type) ) ) AS points_balance
FROM your_table
GROUP BY member_id

Hope that helps :)

Answer 2

For the table below:

CREATE TABLE t_test
 (a INTEGER,
  b INTEGER,
  c VARCHAR(1)
 );

and for the entries below:

INSERT INTO t_test values(1,50,'+');
INSERT INTO t_test values(1,30,'+');
INSERT INTO t_test values(1,15,'-');
INSERT INTO t_test values(2,30,'+');
INSERT INTO t_test values(2,40,'+');

This query works as you expected:

SELECT a,SUM((CONCAT(c,b)) +0) as t FROM t_test group by a;

a   t
1   65
2   70

Answer 3

Similar to the answer

SELECT member_id,
SUM( CASE WHEN plus_minus='+' THEN tran_type ELSE (-1) * tran_type) END) AS points_balance FROM tableX GROUP BY member_id

PS In some DB's tran_type should be float or double..

Answer 4

Can you try the below mentioned sql. You dnt need to use the if condition. SELECT mem_id AS member_id, SUM( tran_type) AS points_balance FROM your_table GROUP BY member_id

Answer 5

您也可以使用

SELECT b.mem_id,SUM(b.tran_points)-(SELECT COALESCE(SUM(a.tran_points),0) FROM tableX AS a WHERE a.plus_minus='-' AND a.mem_id=b.mem_id) AS tran_points FROM tableX AS b WHERE b.plus_minus='+' GROUP BY b.mem_id