sql server选择与之串联吗？

Question

I am trying to select multiple column values and concatenate them into one column. I then want to run a LIKE on the column that the values are selected as. However it does not seem to work.

Here is my SQL query.

SELECT col1 + ' ' + col2 + ' ' + col3 AS colname
FROM tblname
WHERE 'colname' LIKE 'test%'

What is wrong with this query? Is there a better way to do this?

Answer 1

SELECT 
    col1 + ' ' + col2 + ' ' + col3 AS colname 
FROM tblname 
WHERE (col1 + ' ' + col2 + ' ' + col3) LIKE 'test%'

Or

select *
from
(
    SELECT 
        col1 + ' ' + col2 + ' ' + col3 AS colname 
    FROM tblname 
)a
WHERE colname LIKE 'test%'

This is because column aliases cannot be used in a WHERE clause. You either need to explicitly right out what the alias defines, or use a subquery to abstract the alias.