Query untuk menjumlahkan pembayaran installment

installment.sql

select tahun, bulan, sum(payment) as payment
from (
	select year(payment1_dt) tahun, month(payment1_dt) bulan, payment1 payment from tb_dtinstallment
	union all
	select year(payment2_dt) tahun, month(payment2_dt) bulan, payment2 payment from tb_dtinstallment
	union all
	select year(payment3_dt) tahun, month(payment3_dt) bulan, payment3 payment from tb_dtinstallment
	union all
	select year(payment4_dt) tahun, month(payment4_dt) bulan, payment4 payment from tb_dtinstallment
	union all
	select year(payment5_dt) tahun, month(payment5_dt) bulan, payment5 payment from tb_dtinstallment
	union all
	select year(payment6_dt) tahun, month(payment6_dt) bulan, payment6 payment from tb_dtinstallment
	union all
	select year(payment7_dt) tahun, month(payment7_dt) bulan, payment7 payment from tb_dtinstallment
	union all
	select year(payment8_dt) tahun, month(payment8_dt) bulan, payment8 payment from tb_dtinstallment
	union all
	select year(payment9_dt) tahun, month(payment9_dt) bulan, payment9 payment from tb_dtinstallment
	union all
	select year(payment10_dt) tahun, month(payment10_dt) bulan, payment10 payment from tb_dtinstallment
	union all
	select year(payment11_dt) tahun, month(payment11_dt) bulan, payment11 payment from tb_dtinstallment
	union all
	select year(payment12_dt) tahun, month(payment12_dt) bulan, payment12 payment from tb_dtinstallment
	union all
	select year(payment13_dt) tahun, month(payment13_dt) bulan, payment13 payment from tb_dtinstallment
	union all
	select year(payment14_dt) tahun, month(payment14_dt) bulan, payment14 payment from tb_dtinstallment
	union all
	select year(payment15_dt) tahun, month(payment15_dt) bulan, payment15 payment from tb_dtinstallment
) tx
where tahun is not null
group by tahun, bulan