PHP MYSQLiを使用して、action_typeDRおよびCRで管理される債務者と債権者のみを取得する方法

HAVINGを変更するだけでよいようです 句、balanceの場合を除外します ゼロより大きい（債務者）またはbalance ゼロ未満です（債権者）。

条件付きのIF()を使用することもできます dr / crを決定する式 balance 列。

債務者を取得するには のみ：

SELECT client_id, 
       Sum(Coalesce(CASE 
                      WHEN action_type = 'dr' THEN amount 
                    end, 0)) AS total_debits, 
       Sum(Coalesce(CASE 
                      WHEN action_type = 'cr' THEN amount 
                    end, 0)) AS total_credits, 
       Sum(Coalesce(CASE 
                      WHEN action_type = 'cr' THEN amount 
                    end, 0)) - Sum(Coalesce(CASE 
                                              WHEN action_type = 'dr' THEN 
                                              amount 
                                            end, 0)) AS total_debtors, 
       IF(Sum(Coalesce(CASE 
                         WHEN action_type = 'cr' THEN amount 
                       end, 0)) - Sum(Coalesce(CASE 
                                                 WHEN action_type = 'dr' THEN 
                                                 amount 
                                               end, 0)) > 0, 'dr', 'cr') AS balance 
FROM   tbl_balancesheet 
GROUP  BY client_id 
HAVING balance = 'dr' AND total_debtors <> 0

債権者を取得するには のみ：

SELECT client_id, 
       Sum(Coalesce(CASE 
                      WHEN action_type = 'dr' THEN amount 
                    end, 0)) AS total_debits, 
       Sum(Coalesce(CASE 
                      WHEN action_type = 'cr' THEN amount 
                    end, 0)) AS total_credits, 
       Sum(Coalesce(CASE 
                      WHEN action_type = 'cr' THEN amount 
                    end, 0)) - Sum(Coalesce(CASE 
                                              WHEN action_type = 'dr' THEN 
                                              amount 
                                            end, 0)) AS total_debtors, 
       IF(Sum(Coalesce(CASE 
                         WHEN action_type = 'cr' THEN amount 
                       end, 0)) - Sum(Coalesce(CASE 
                                                 WHEN action_type = 'dr' THEN 
                                                 amount 
                                               end, 0)) > 0, 'dr', 'cr') AS balance 
FROM   tbl_balancesheet 
GROUP  BY client_id 
HAVING balance = 'cr' AND total_debtors <> 0