在select中使用Case显示其他列

Question

使用SQL 2008，我有这段代码：

    if (exists (select * from tempdb.INFORMATION_SCHEMA.TABLES where TABLE_NAME = '##tempz'))
begin
drop table ##tempz
end
else
DECLARE @startDate datetime, @enddate datetime, @storename varchar(20), @showstore int, @showcashier int, @showregister int, @showdate int
SET @startDate = '1/1/2011'
SET @enddate = '1/1/2013'
SET @storename = '01'
SET @showstore = 1
SET @showcashier = 1
SET @showregister = 1
SET @showdate = 1

DECLARE @cols AS NVARCHAR(MAX),@colsNull AS NVARCHAR(MAX),@query  AS NVARCHAR(MAX)
SELECT @cols = STUFF((SELECT DISTINCT ',' + QUOTENAME(c.CurrencyDesc)
FROM rpPay p LEFT JOIN RPTrs r ON p.ReceiptNo = r.ReceiptNo LEFT JOIN Currencies c ON c.POSCurrency = LEFT(p.paytype,1)
WHERE r.trsdate >= @startDate AND r.trsdate <= @enddate
FOR XML PATH(''), TYPE ).value('.', 'NVARCHAR(MAX)'),1,1,'')

SELECT @colsNull = STUFF((SELECT DISTINCT ', IsNull(' + QUOTENAME(c.CurrencyDesc) +', 0) as '+ QUOTENAME(c.CurrencyDesc)
FROM rpPay p LEFT JOIN RPTrs r ON p.ReceiptNo = r.ReceiptNo LEFT JOIN Currencies c ON LEFT(p.paytype,1) = c.POSCurrency
WHERE r.trsdate >= @startDate AND r.trsdate <= @enddate
FOR XML PATH(''), TYPE ).value('.', 'NVARCHAR(MAX)'),1,1,'')

SET @query = 'select date, cashregister, storeid, cashier, '+@colsNull+' into ##tempz
FROM
(SELECT cast(r.trsdate AS DATE) date,c.CurrencyDesc,p.amount,r.cashregister,r.storeid,r.cashier
FROM rpPay p LEFT JOIN RPTrs r ON p.ReceiptNo = r.receiptno LEFT JOIN Currencies c ON LEFT(p.paytype,1) = c.POSCurrency
WHERE r.trsdate >= '''+ convert(varchar(10), @startDate, 101) +''' AND r.trsdate <= '''+ convert(varchar(10), @endDate, 101) +''' 
) p
pivot
(sum(amount) FOR CurrencyDesc in('+@cols+')) piv'
execute(@query)

select * from ##tempz

返回

我想要的是，如果其中任何一个：

SET @showstore = 1
SET @showcashier = 1
SET @showregister = 1
SET @showdate = 1

是0，那么我不想在结果窗口中显示它。因此，如果@showcashier为0，则Cashier将不会显示

Answer 1

你不能，使用常规SQL。 SQL语句返回的列已定义。

你有三种选择。第一种是在应用程序级别选择列。第二种是返回NULL值（如果语法正确，这是你的查询会做的。第三种是使用“动态”sql。也就是说，生成一个SQL查询作为字符串，然后执行它。

第三个选项取决于您使用的数据库。

Answer 2

这样做的一种方法是使用这样的存储过程：

CREATE PROCEDURE GetData
    @show tinyint
AS
BEGIN
    IF @show = 1
    BEGIN
        select CurrencyDesc, POSCurrency from Currencies;
    END
    ELSE
        select CurrencyDesc from Currencies;
END 

而不是像这样执行：

exec GetData 1 -- returns 2 columns

exec GetData 0 -- returns one column