这是一个将字符串拆分为行的函数。下面是对您的 demorecords 表的查询,该表使用该函数来获取请求的结果。
create function dbo.split
(
@delimited nvarchar(max),
@delimiter nvarchar(5)
)
returns @rows table
(
rownumber int not null identity(1,1),
value nvarchar(max) not null
)
as
begin
if @delimited is null return
declare @delr_len int = len(@delimiter)
declare @start_at int = 1
declare @end_at int
declare @deld_len int
while 1=1
begin
set @end_at = charindex(@delimiter,@delimited,@start_at)
set @deld_len = case @end_at when 0 then len(@delimited) else @end_at-@start_at end
insert into @rows (value) values( substring(@delimited,@start_at,@deld_len) );
if @end_at = 0 break;
set @start_at = @end_at + @delr_len
end
return
end
go
select custid, customername, currencycode=currencycode.value, currentbalance=currentbalance.value, datevalue=datevalue.value
from demorecords r
cross apply (select rownumber, value from dbo.split(r.currencycode,'ý') ) currencycode
cross apply (select rownumber, value from dbo.split(r.currentbalance,'ý') where rownumber = currencycode.rownumber ) currentbalance
cross apply (select rownumber, value from dbo.split(r.datevalue,'ý') where rownumber = currencycode.rownumber ) datevalue
如果您有一列可能包含缺失值,请使用外部应用而不是内部应用来连接该列的函数结果。在以下示例中,DateValue 列缺少值 3 和值 4。
INSERT INTO DemoRecords VALUES ('Mr. X', 'BDTýUSDýGBPýEUR','10500ý2500ý1050ý','ý')
select custid, customername, currencycode=currencycode.value, currentbalance=currentbalance.value, datevalue=datevalue.value
from demorecords r
cross apply (select rownumber, value from dbo.split(r.currencycode,'ý') ) currencycode
cross apply (select rownumber, value from dbo.split(r.currentbalance,'ý') where rownumber = currencycode.rownumber ) currentbalance
outer apply (select rownumber, value from dbo.split(r.datevalue,'ý') where rownumber = currencycode.rownumber ) datevalue
或者,您可以清理输入以不丢失值。在上面的例子中,我希望 DateValue 是 'ýý' 而不是 'ý'。如果您的情况允许,您可能更喜欢查找和修复这些问题,而不是使用外连接。