求高手指点，关于Format函数问题

Question

sql.Format("select a.bookname,a.barcode,a.author,a.bookconcern,a.price,b.numbers from tb_bookinfo a inner join (select barcode,sum(numbers) numbers from tb_sell_sub group by barcode)as b on a.barcode = b.barcode and a.bookname = '%s' order by b.numbers desc",c_value);(select barcode,sum(numbers) numbers from tb_sell_sub group by barcode)as b这个是什么意思呢？on后面的意思我懂

Answer 1

首先把格式化字符串进行格式化，然后再用格式化字符串去做最终转换。
可以这样：
CString sFmt;sFmt.Format( "%%.%df", n );//假设n是你要想的小数点后的位数，比如3。经过这一行之后，sFmt的值应该为“%.3f”了。str.Format( sFmt.GetBuffer(), number );//等同于str.Format( "%.3f", number )