select data up to a space?

问题

I have an MSSQL database field that looks like the examples below:

u129  james
u300  chris
u300a jim
u202  jane
u5    brian
u5z   brian2

Is there a way to select the first set of characters? Basically select all the characters up until the first line space?

I tried messing around with LEFT, RIGHT, LEN, but couldn't figure out a way to do it with variable string lengths like in my example.

Thanks!

回答1:

You can use a combiation of LEFT and CHARINDEX to find the index of the first space, and then grab everything to the left of that.

 SELECT LEFT(YourColumn, charindex(' ', YourColumn) - 1) 

And in case any of your columns don't have a space in them:

SELECT LEFT(YourColumn, CASE WHEN charindex(' ', YourColumn) = 0 THEN 
    LEN(YourColumn) ELSE charindex(' ', YourColumn) - 1 END)

回答2:

select left(col, charindex(' ', col) - 1)

回答3:

An alternative if you sometimes do not have spaces do not want to use the CASE statement

select REVERSE(RIGHT(REVERSE(YourColumn), LEN(YourColumn) - CHARINDEX(' ', REVERSE(YourColumn))))

This works in SQL Server, and according to my searching MySQL has the same functions

回答4:

If the first column is always the same size (including the spaces), then you can just take those characters (via LEFT) and clean up the spaces (with RTRIM):

SELECT RTRIM(LEFT(YourColumn, YourColumnSize))

Alternatively, you can extract the second (or third, etc.) column (using SUBSTRING):

SELECT RTRIM(SUBSTRING(YourColumn, PreviousColumnSizes, YourColumnSize))

One benefit of this approach (especially if YourColumn is the result of a computation) is that YourColumn is only specified once.

来源：https://stackoverflow.com/questions/13481084/select-data-up-to-a-space