Question

当我运行此SQL代码时：

declare @a as int=0;
declare @b as int=1;
declare @c as char(4)='c'
declare @d as varchar(4)='d'  

set @c = @c + cast(@a as char(1)) + cast(@b as char(1))
select @c

set @d = @d + cast(@a as char(1)) + cast(@b as char(1))
select @d

它返回

c
d01

有没有办法成功将数字转换为char并添加到char(n)变量？

我也想知道为什么会这样。

Answer 1

来自MSDN

char [（n）]

固定长度的非Unicode字符串数据。 n定义了   字符串长度，必须是1到8,000之间的值。存储   大小是n个字节。

@a变量已占用4个字节，因此您无法再添加任何字符。

declare @c as char(4)='c'

这里已经@c占用了四个字节，即使您只传递了一个字节c。

当您使用@c分配@c + cast(@a as char(1)) + cast(@b as char(1))时转换为4 + 1 + 1 = 6 @c无法容纳。

Answer 2

试试这个：

declare @a as int=0;
declare @b as int=1;
declare @c as char(4)='c' -- here @c = 'c   '
declare @d as varchar(4)='d'  

set @c = RTrim( @c ) + cast(@a as char(1)) + cast(@b as char(1))
select @c

set @d = @d + cast(@a as char(1)) + cast(@b as char(1))
select @d

如果你不修剪@c，已经满了（有3个空格），所以其他所有动作都会被截断。

SQL Server：将数字连接到varchar字段有效，但进入char字段不起作用。有任何想法吗？

2 个答案: