SQL DB2 自动修剪尾随空格
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DB2 automatic trim tailing whitespace
提问by Fuangwith S.
This is data in TB_USER table
这是 TB_USER 表中的数据
USER_USERID
--------------
A111
A9999
ADMIN
AHO
AHO2
AHO3
AHO4
...and schema of TB_USER table is
...和 TB_USER 表的架构是
COLUMN_NAME DATA_TYPE DATA_LENGTH
-------------------- --------- -----------
USER_USERID VARCHAR 15
When I execute following SELECT statement:
当我执行以下 SELECT 语句时：
SELECT USER_USERID FROM TB_USER WHERE USER_USERID = 'ADMIN '
...and:
...和：
SELECT USER_USERID FROM TB_USER WHERE USER_USERID = 'ADMIN'
DB2 retreive same output following
DB2 检索以下相同的输出
USER_USERID
--------------
ADMIN
How to fix this problem?
如何解决这个问题？
回答by Michael Sharek
回答by Michael Hvizdos
This behaviour is as designed - equality predicates for string comparisons won't consider trailing spaces. As Rakesh suggested, the LIKE predicate will consider the trailing spaces. It depends upon your use case which you should go with.
此行为是按设计的 - 字符串比较的相等谓词不会考虑尾随空格。正如 Rakesh 所建议的，LIKE 谓词将考虑尾随空格。这取决于您应该使用的用例。
Relevant documentation:
相关文档：
DB2 9.7 Infocenter - Assignments and comparisons
"When comparing character strings of unequal lengths, the comparison is made using a logical copy of the shorter string, which is padded on the right with blanks sufficient to extend its length to that of the longer string. This logical extension is done for all character strings, including those tagged as FOR BIT DATA."
"当比较长度不等的字符串时，比较是使用较短字符串的逻辑副本进行的，该副本在右侧填充足够的空格以将其长度扩展到较长字符串的长度。此逻辑扩展对所有字符进行字符串，包括标记为 FOR BIT DATA 的字符串。”
DB2 9.7 Infocenter - LIKE predicate
"The LIKE predicate searches for strings that have a certain pattern. The pattern is specified by a string in which the underscore and the percent sign may have special meanings. Trailing blanks in a pattern are part of the pattern."
“LIKE 谓词搜索具有特定模式的字符串。该模式由一个字符串指定，其中下划线和百分号可能具有特殊含义。模式中的尾随空格是该模式的一部分。”
回答by Rakesh Juyal
Instead of
代替
SELECT USER_USERID FROM TB_USER WHERE USER_USERID = 'ADMIN '
Use
用
SELECT USER_USERID FROM TB_USER WHERE USER_USERID like 'ADMIN '
