计算字段

SELECT
   RTRIM(Name),
   LTRIM(Name),
   TRIM(Name)
FROM country


RTRIM(Name) LTRIM(Name) TRIM(Name)
Aruba Aruba Aruba
Afghanistan Afghanistan Afghanistan
Angola Angola Angola
Anguilla Anguilla Anguilla
Albania Albania Albania
Andorra Andorra Andorra
Netherlands Antilles Netherlands Antilles Netherlands Antilles
United Arab Emirates United Arab Emirates United Arab Emirates
Argentina Argentina Argentina
...

RTRIM() 去掉值右侧的所有空格。 LTRIM() 去掉值左侧的所有空格。 TRIM() 两侧的空格都去掉。