How to optimize MSSQL CASE WHEN queries - sql

Question

Here's a sample of my code:
SET #variable_out =
'Report: '
+ CASE WHEN (SELECT name FROM person WITH(NOLOCK) WHERE person_id = #person_id) != ''
THEN 'Name: ' + (SELECT name FROM person WITH(NOLOCK) WHERE person_id = #person_id) + CHAR(13)+CHAR(10)
ELSE 'Name: not found' + CHAR(13)+CHAR(10)
END
+ CASE WHEN (SELECT home_phone FROM person WITH(NOLOCK) WHERE person_id = #person_id) != ''
THEN 'Phone #: ' + (SELECT home_phone FROM person WITH(NOLOCK) WHERE person_id = #person_id) + CHAR(13)+CHAR(10)
ELSE 'Phone #: not found' + CHAR(13)+CHAR(10)
END
etc...
As you can see, I am redundantly performing two selects for each CASE WHENE... of the variable that I am constructing, and I would love to collapse this down to only one select for each line.
The only solution I know of would be to create a unique variable for CASE WHEN..., run all of the selects before hand, and then if the variables aren't empty, concat them into #variable_out.
Is there a more clever way to accomplish this?

Answer 1

DECLARE #name the_same_datatype_as_name_field_from_person_table --Ex. VARCHAR(100)
,#home_phone the_same_datatype_as_homephone_field_from_person_table; --Ex. VARCHAR(15)
SELECT #name = NULLIF(p.name,''), #home_phone = NULLIF(p.home_phone,'')
FROM person p --WITH(NOLOCK)
WHERE p.person_id = #person_id;
SET #variable_out =
'Report: '
+ ISNULL('Name: ' + #name, 'Name: not found')
+ CHAR(13)+CHAR(10)
+ ISNULL('Phone #: ' + #home_phone, 'Phone #: not found')
+ CHAR(13)+CHAR(10);
Note:
or, you can use for #name & #home_phone variables the same data type like as #variable_out variable (ex. VARCHAR).
NOLOCK pros & cons.