How to concatenate two or more DB columns into one SELECT column

[HFChristie]

How do I code a SELECT statement so that the values in two columns are combined into one result?

For instance;
SELECT (col_a || col_b) AS col_a_b
FROM table_a

(col_a and col_b are character data type)

I thought "+" could be used, but thats returning data type error. I also tried | and ||, but they both fail.

Also, if you know this, do you know how to have it return a value even if one of the columns is NULL?

Thank you

 

[kewo99]

Use the ampersand (&) for strings.
col_a & col_b

To get past Null, use an empty string ""
col_a & col_b & ""