T-SQL：如何反转字符串中的值

Question

Using T-SQL, I'm trying to find the easiest way to make "Test One" become "One, Test" .

Basically switch the " " and ", " if there are just 2 words in a column with a space between them.

For example:

Before             After
Test One           One, Test
Test Two One       Test Two One
Test, Three        Test, Three

Answer 1

How about this:

select col Before,
  case 
    when col like '%,%' then col 
    when len(replace(col, ' ', '')) = len(col) -1 
      then reverse(substring(reverse(col), 1, charindex(' ', reverse(col))-1))+', '+substring(col, 1, charindex(' ', col)-1)
    else col
  end  After
from yourtable

See SQL Fiddle with Demo . The result is:

|       BEFORE |        AFTER |
-------------------------------
|     Test One |    One, Test |
| Test Two One | Test Two One |
|  Test, Three |  Test, Three |

Answer 2

SQL Fiddle

DECLARE @Tests TABLE (
    Before VARCHAR(50)
)

INSERT INTO @Tests Values ('Test One')
INSERT INTO @Tests Values ('Test Two One')
INSERT INTO @Tests Values ('Test, Three')

SELECT
    Before,
    CASE 
        WHEN 
            -- If there is no comma...
            CHARINDEX(',', Before) = 0
            -- And if there is only one space... 
            AND CHARINDEX(' ', RIGHT(Before, LEN(Before) - 
                CHARINDEX(' ', Before))) = 0
        THEN 
            -- Then perform the swap.
            RIGHT(Before, LEN(Before) - CHARINDEX(' ', Before)) + ', ' 
            + LEFT(Before, CHARINDEX(' ', Before))
        -- Otherwise, retain the "before" value.
        ELSE Before
    END AS After
FROM @Tests

Answer 3

Here is my take : Not the best as it uses quiet a number of string functions...

• Assumptions:

  1. That you only have two words ;)

  2. There is a space/ or ther character...

• SQLFIDDLE DEMO

Code:

SELECT CHARINDEX(' ',name) splitposition,
SUBSTRING(name, 1, CHARINDEX(' ',name)-1) firstword,
SUBSTRING(name, CHARINDEX(' ',name), len(name)) lastword,
(SUBSTRING(name, CHARINDEX(' ',name), len(name)) +
', ' + SUBSTRING(name, 1, CHARINDEX(' ',name)-1)) as swapped
from moneys;

Results:

| SPLITPOSITION | FIRSTWORD | LASTWORD |   SWAPPED |
----------------------------------------------------
|             5 |      test |      one |  one, test |

ps: I used an old table in sql server for the demo..