根据同一表中另一个字段的值获取Mysql编号的净值

Question

I am using the below query for getting the net value of a number(amount) field in my table. The net value is calculating based on the type of a field called transaction type. Can anybody help me by advising is there any way to simplify my below query.

    select (select sum(jvm_txn_amount) from jvm_transactions
           where  jvm_txn_mode = 'CASH' and 
           jvm_txn_type = 'Receipt' and 
           jvm_txn_mnt_stat = 'A') - 
           (select sum(jvm_txn_amount) from   jvm_transactions
           where  jvm_txn_mode = 'CASH' and 
           jvm_txn_type = 'Payment' and 
           jvm_txn_mnt_stat = 'A')as net_balance
    from   dual

Answer 1

Possibly start by grouping by jvm_txn_type :

SELECT SUM(IF(x.type='Receipt', s, 0)) - 
       SUM(IF(x.type='Payment', s, 0)) AS net_balance FROM 
       (  SELECT jvm_txn_type type,  SUM(jvm_txn_amount) s
            FROM jvm_transactions
           WHERE jvm_txn_mode = 'CASH'
             AND jvm_txn_mnt_stat = 'A'
        GROUP BY jvm_txn_type
       ) x

It's somewhat more compact and less repetitive, which ought to make it a little more versatile and easier to maintain.