SELECT mode/modal value SQL

Question

My first table dbo.Port contains aggregated details about each portfolio

Portfolio   Yield   Duration    Coupon
Port1       0.62    1.10        0.98
Port2       0.52    0.91        2.46
Port3       0.40    0.70        0.37

My second table dbo.Security contains details about each portfolios individual securities

Portfolio   Security    Yield   Duration    Coupon  Country Sector  MarketValue
Port1       Sec1        0.35    0.50        2.25    US      CORP    386.17
Port1       Sec2        0.16    0.23        1.75    UK      CORP    224.64
Port1       Sec3        0.98    1.96        3.00    US      CORP    148.00
Port1       Sec4        0.78    1.40        0.00    DE      SOV     980.07
Port2       Sec1        0.35    0.50        2.25    US      CORP    386.17
Port2       Sec3        0.98    1.96        3.00    US      CORP    148.00
Port3       Sec1        0.35    0.50        2.25    US      CORP    386.17
Port3       Sec4        0.78    1.40        0.00    DE      SOV     980.07
Port3       Sec5        0.03    0.06        0.00    DE      SOV     952.36

I can retrieve the modal country for portfolio 1 with the below separate query. which isUS

SELECT x.Country 
FROM (
    SELECT TOP 1 COUNT(dbo.Security.Country) as Count ,dbo.Security.Country
    FROM dbo.Port
    INNER JOIN dbo.Security ON (dbo.Port.Portfolio = dbo.Security.Portfolio)
    WHERE dbo.Port.Portfolio = 'Port1'
    GROUP BY dbo.Security.Country
    ORDER BY Count DESC
    ) x

What I want my query to return is to return a joined query that selects the modal values of country and sector for each portfolio. Does anyone know how to incorporate this query into the first query or any other method so that I can retrieve MODE(dbo.Security.Country) etc. for each portfolio so that I end up with the below table

Portfolio   Yield   Duration    Coupon  Market Value    Country Sector
Port1       0.62    1.10        0.98    1738.88         US      CORP
Port2       0.52    0.91        2.46    534.17          US      CORP
Port3       0.40    0.70        0.37    2318.60         DE      SOV

Desired SQL

SELECT 
dbo.Port.Portfolio
,dbo.Port.Yield
,dbo.Port.Duration
,dbo.Port.Coupon
,SUM(dbo.Security.MarketValue)

 --Not working
,MODE(dbo.Security.Country)
,MODE(dbo.Security.Sector)  
--Not working

FROM dbo.Port
INNER JOIN dbo.Security ON (dbo.Port.Portfolio = dbo.Security.Portfolio)

GROUP BY
dbo.Port.Portfolio
,dbo.Port.Yield
,dbo.Port.Duration
,dbo.Port.Coupon

Answer 1

First of all, your query to retrieve the model country for portfolio 1 should include an ORDER BY clause otherwise it will just return the country of the first row that matches the WHERE clause.

Secondly, you could achieve the desired output using inline queries:

SELECT 
P.Portfolio
,P.Yield
,P.Duration
,P.Coupon
,SUM(S.MarketValue)
,( SELECT TOP 1 Country FROM dbo.Security WHERE Portfolio = P.Portfolio GROUP BY Country ORDER BY COUNT(*) DESC ) Country
,( SELECT TOP 1 Sector FROM dbo.Security WHERE Portfolio = P.Portfolio GROUP BY Sector ORDER BY COUNT(*) DESC ) Sector
FROM dbo.Port P
INNER JOIN dbo.Security S ON (P.Portfolio = S.Portfolio)
GROUP BY
P.Portfolio
,P.Yield
,P.Duration
,P.Coupon