declare @des_str varchar(4000)
declare @str_maxlen int
set @des_str='aa,bb,cc,dd,ee,' --字符串
set @str_maxlen=5 --字符串中","的个数
declare @step int
declare @num1 int
declare @str1 varchar(20)
declare @num2 int
set @step=0
set @num1=0
set @num2=0
while @step<@str_maxlen
begin
set @num1=charindex(',',@des_str,@num2)
set @str1=substring(@des_str,@num2,@num1-@num2)
set @num2=@num1+1
set @step=@step+1