在 Oracle SQL 中连接字符串而中间没有空格？
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Concatenate strings in Oracle SQL without a space in between?
提问by brainless
I am trying to concatenate strings in oracle.
我正在尝试在 oracle 中连接字符串。
The following is my query:
以下是我的查询：
insert into dummy values('c'||to_char(10000,'99999'));
The expected result is:
预期的结果是：
c10000
But the output I get is with a space in between 'c' and the value 10000:
但是我得到的输出在 'c' 和值 10000 之间有一个空格：
c 10000
How to concat without spaces?
如何在没有空格的情况下进行连接？
回答by Erwin Brandstetter
This is not an issue with the concatenation operator but with the function to_char(). Try instead:
这不是连接运算符的问题，而是函数的问题to_char()。试试吧：
to_char(10000,'FM99999')
I quote the manual here:
FM .. Returns a value with no leading or trailing blanks.
FM .. 返回一个没有前导或尾随空格的值。
回答by PaulK
There are two solutions:
有两种解决方案：
- Fill Mode ('
FM') formatting prefix that suppresses the additional blank character prefix for theto_charnumber conversion. I suggest this one is preferred, because it is integrated with the to_char format and does not require an additional function call; LTRIMof the returned value from theto_charnumber conversion.
- 填充模式 ('
FM') 格式前缀，用于抑制to_char数字转换的额外空白字符前缀。我建议首选这个，因为它集成了 to_char 格式，不需要额外的函数调用； LTRIMto_char数字转换的返回值。
The code below shows the results of both solutions:
下面的代码显示了两种解决方案的结果：
Select concat('NTA', to_char(1,'FM0000000000000')),
concat('NTA', ltrim(to_char(1,'0000000000000'))),
concat('NTA', to_char(1,'0000000000000'))
from dual;
"CONCAT('NTA',TO_CHAR(1,'FM0000000000000'))": "NTA0000000000001"
"CONCAT('NTA',LTRIM(TO_CHAR(1,'0000000000000')))": "NTA0000000000001"
"CONCAT('NTA',TO_CHAR(1,'0000000000000'))": "NTA 0000000000001"
"CONCAT('NTA',TO_CHAR(1,'FM0000000000000'))"：“NTA0000000000001”
"CONCAT('NTA',LTRIM(TO_CHAR(1,'0000000000000')))"：“NTA0000000000001”
"CONCAT('NTA',TO_CHAR(1,'0000000000000'))"：“NTA 0000000000001”
