如何在MySQL中使用选择大小写

Question

以下是MSSQL语法，如何将其转换为mysql

    SELECT          
    _nextBillingDate = UB.NextBillingDate,
    _billingFrequency = (CASE IFNULL(UB.BillingFrequency,0) WHEN 0 THEN
     _defaultBillingFrequency ELSE UB.BillingFrequency END),
    _isCompletelyCreditBilled = (CASE WHEN PO.ChargeAmount > 0 THEN 0 ELSE 1 END),
    _ownerId = PO.OwnerId   
    FROM PaymentOrder PO
    INNER JOIN UserBillingInfo UB ON PO.OwnerId = UB.OwnerId
    WHERE PO.Id = _paymentOrderId

Answer 1

-- DECLARE variables at the top of your procedure

SELECT
    UB.NextBillingDate,
    CASE IFNULL(UB.BillingFrequency,0) WHEN 0 THEN _defaultBillingFrequency ELSE UB.BillingFrequency END,
    CASE WHEN PO.ChargeAmount > 0 THEN 0 ELSE 1 END,
    PO.OwnerId
INTO
    _nextBillingDate, _billingFrequency, _isCompletelyCreditBilled, _ownerId 
FROM PaymentOrder PO
INNER JOIN UserBillingInfo UB ON PO.OwnerId = UB.OwnerId
WHERE PO.Id = _paymentOrderId

Answer 2

创建表newtable SELECT * FROM oldtable