mysql case 函数使用demo

SELECT
purchase.id,
purchase.purchase_count,
purchase.unit_price,
purchase.asset_total_price,
purchase.purpose,
purchase.asset_status,
purchase.receive_person_id,
purchase.remarks,
purchase.del_flag,
purchase.org_id,
COUNT(1) AS countBill,
SUM(purchase.asset_total_price) AS applyPrice,
COUNT(
CASE WHEN purchase.asset_status = ‘2’ THEN 1 ELSE NULL END ) AS isBuyCount,
COUNT(
CASE WHEN purchase.asset_status = ‘3’ THEN 1 ELSE NULL END ) AS uselessBill,
SUM(
CASE WHEN purchase.asset_status = ‘2’ THEN purchase.asset_total_price ELSE 0 END ) AS isBuyPrice
FROM
bus_purchase_apply AS purchase
GROUP BY
purchase.receive_person_id
HAVING
purchase.del_flag = ‘0’
AND purchase.org_id = ‘1’