web-dev-qa-db-fra.com

Moyenne de plusieurs colonnes

J'ai une table appelée Request et les données ressemblent à:

Req_ID    R1   R2   R3   R4   R5

R12673    2    5    3    7    10
R34721    3    5    2    1    8
R27835    1    3    8    5    6

Maintenant, je veux afficher la moyenne de R1, R2, R3, R4 et R5

J'ai donc écrit une requête comme:

Select Req_ID, Avg(R1+R2+R3+R4+R5) as Average
from Request
Group by Req_ID

Mais je viens de recevoir la somme de R1, R2, R3, R4 et R5 pas la moyenne? Où est-ce que je fais mal.

sqlsql-server-2005tsqlsql-server-2008
25
Peter

Si les données sont stockées en tant que INT, vous voudrez peut-être essayer

Average = (R1 + R2 + R3 + R4 + R5) / 5.0
15
Aaron Bertrand

Vous ne mentionnez pas si les colonnes peuvent être annulées. S'ils le sont et que vous voulez la même sémantique que l'agrégat AVG vous permet de faire (2008)

SELECT *,
       (SELECT AVG(c)
        FROM   (VALUES(R1),
                      (R2),
                      (R3),
                      (R4),
                      (R5)) T (c)) AS [Average]
FROM   Request

La version 2005 est un peu plus fastidieuse

SELECT *,
       (SELECT AVG(c)
        FROM   (SELECT R1
                UNION ALL
                SELECT R2
                UNION ALL
                SELECT R3
                UNION ALL
                SELECT R4
                UNION ALL
                SELECT R5) T (c)) AS [Average]
FROM   Request
33
Martin Smith

Vous pourriez simplement faire:

Select Req_ID, (avg(R1)+avg(R2)+avg(R3)+avg(R4)+avg(R5))/5 as Average
from Request
Group by Req_ID

Droite?

Je suppose que vous pouvez avoir plusieurs lignes avec le même Req_ID et dans ces cas, vous voulez calculer la moyenne sur toutes les colonnes et lignes pour ces lignes avec le même Req_ID

4
beetree

Dans PostgreSQL, pour obtenir la moyenne de plusieurs (2 à 8) colonnes sur une ligne, il suffit de définir un ensemble de sept fonctions appelées average (). Produira la moyenne des colonnes non nulles.

Et puis juste

select *,(r1+r2+r3+r4+r5)/5.0,average(r1,r2,r3,r4,r5) from request;
 req_id | r1 | r2 | r3 | r4 | r5 |      ?column?      |      average
--------+----+----+----+----+----+--------------------+--------------------
 R12673 |  2 |  5 |  3 |  7 | 10 | 5.4000000000000000 | 5.4000000000000000
 R34721 |  3 |  5 |  2 |  1 |  8 | 3.8000000000000000 | 3.8000000000000000
 R27835 |  1 |  3 |  8 |  5 |  6 | 4.6000000000000000 | 4.6000000000000000
(3 rows)

update request set r4=NULL where req_id='R34721';
UPDATE 1

select *,(r1+r2+r3+r4+r5)/5.0,average(r1,r2,r3,r4,r5) from request;
 req_id | r1 | r2 | r3 | r4 | r5 |      ?column?      |      average
--------+----+----+----+----+----+--------------------+--------------------
 R12673 |  2 |  5 |  3 |  7 | 10 | 5.4000000000000000 | 5.4000000000000000
 R34721 |  3 |  5 |  2 |    |  8 |                    | 4.5000000000000000
 R27835 |  1 |  3 |  8 |  5 |  6 | 4.6000000000000000 | 4.6000000000000000
(3 rows)

select *,(r3+r4+r5)/3.0,average(r3,r4,r5) from request;
 req_id | r1 | r2 | r3 | r4 | r5 |      ?column?      |      average
--------+----+----+----+----+----+--------------------+--------------------
 R12673 |  2 |  5 |  3 |  7 | 10 | 6.6666666666666667 | 6.6666666666666667
 R34721 |  3 |  5 |  2 |    |  8 |                    | 5.0000000000000000
 R27835 |  1 |  3 |  8 |  5 |  6 | 6.3333333333333333 | 6.3333333333333333
(3 rows)

Comme ça:

CREATE OR REPLACE FUNCTION AVERAGE (
V1 NUMERIC,
V2 NUMERIC)
RETURNS NUMERIC
AS $FUNCTION$
DECLARE
    COUNT NUMERIC;
    TOTAL NUMERIC;
BEGIN
    COUNT=0;
    TOTAL=0;
    IF V1 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V1; END IF;
    IF V2 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V2; END IF;
    RETURN TOTAL/COUNT;
    EXCEPTION WHEN DIVISION_BY_ZERO THEN RETURN NULL;
END
$FUNCTION$ LANGUAGE PLPGSQL;

CREATE OR REPLACE FUNCTION AVERAGE (
V1 NUMERIC,
V2 NUMERIC,
V3 NUMERIC)
RETURNS NUMERIC
AS $FUNCTION$
DECLARE
    COUNT NUMERIC;
    TOTAL NUMERIC;
BEGIN
    COUNT=0;
    TOTAL=0;
    IF V1 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V1; END IF;
    IF V2 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V2; END IF;
    IF V3 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V3; END IF;
    RETURN TOTAL/COUNT;
    EXCEPTION WHEN DIVISION_BY_ZERO THEN RETURN NULL;
END
$FUNCTION$ LANGUAGE PLPGSQL;

CREATE OR REPLACE FUNCTION AVERAGE (
V1 NUMERIC,
V2 NUMERIC,
V3 NUMERIC,
V4 NUMERIC)
RETURNS NUMERIC
AS $FUNCTION$
DECLARE
    COUNT NUMERIC;
    TOTAL NUMERIC;
BEGIN
    COUNT=0;
    TOTAL=0;
    IF V1 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V1; END IF;
    IF V2 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V2; END IF;
    IF V3 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V3; END IF;
    IF V4 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V4; END IF;
    RETURN TOTAL/COUNT;
    EXCEPTION WHEN DIVISION_BY_ZERO THEN RETURN NULL;
END
$FUNCTION$ LANGUAGE PLPGSQL;

CREATE OR REPLACE FUNCTION AVERAGE (
V1 NUMERIC,
V2 NUMERIC,
V3 NUMERIC,
V4 NUMERIC,
V5 NUMERIC)
RETURNS NUMERIC
AS $FUNCTION$
DECLARE
    COUNT NUMERIC;
    TOTAL NUMERIC;
BEGIN
    COUNT=0;
    TOTAL=0;
    IF V1 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V1; END IF;
    IF V2 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V2; END IF;
    IF V3 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V3; END IF;
    IF V4 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V4; END IF;
    IF V5 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V5; END IF;
    RETURN TOTAL/COUNT;
    EXCEPTION WHEN DIVISION_BY_ZERO THEN RETURN NULL;
END
$FUNCTION$ LANGUAGE PLPGSQL;

CREATE OR REPLACE FUNCTION AVERAGE (
V1 NUMERIC,
V2 NUMERIC,
V3 NUMERIC,
V4 NUMERIC,
V5 NUMERIC,
V6 NUMERIC)
RETURNS NUMERIC
AS $FUNCTION$
DECLARE
    COUNT NUMERIC;
    TOTAL NUMERIC;
BEGIN
    COUNT=0;
    TOTAL=0;
    IF V1 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V1; END IF;
    IF V2 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V2; END IF;
    IF V3 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V3; END IF;
    IF V4 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V4; END IF;
    IF V5 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V5; END IF;
    IF V6 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V6; END IF;
    RETURN TOTAL/COUNT;
    EXCEPTION WHEN DIVISION_BY_ZERO THEN RETURN NULL;
END
$FUNCTION$ LANGUAGE PLPGSQL;

CREATE OR REPLACE FUNCTION AVERAGE (
V1 NUMERIC,
V2 NUMERIC,
V3 NUMERIC,
V4 NUMERIC,
V5 NUMERIC,
V6 NUMERIC,
V7 NUMERIC)
RETURNS NUMERIC
AS $FUNCTION$
DECLARE
    COUNT NUMERIC;
    TOTAL NUMERIC;
BEGIN
    COUNT=0;
    TOTAL=0;
    IF V1 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V1; END IF;
    IF V2 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V2; END IF;
    IF V3 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V3; END IF;
    IF V4 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V4; END IF;
    IF V5 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V5; END IF;
    IF V6 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V6; END IF;
    IF V7 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V7; END IF;
    RETURN TOTAL/COUNT;
    EXCEPTION WHEN DIVISION_BY_ZERO THEN RETURN NULL;
END
$FUNCTION$ LANGUAGE PLPGSQL;

CREATE OR REPLACE FUNCTION AVERAGE (
V1 NUMERIC,
V2 NUMERIC,
V3 NUMERIC,
V4 NUMERIC,
V5 NUMERIC,
V6 NUMERIC,
V7 NUMERIC,
V8 NUMERIC)
RETURNS NUMERIC
AS $FUNCTION$
DECLARE
    COUNT NUMERIC;
    TOTAL NUMERIC;
BEGIN
    COUNT=0;
    TOTAL=0;
    IF V1 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V1; END IF;
    IF V2 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V2; END IF;
    IF V3 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V3; END IF;
    IF V4 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V4; END IF;
    IF V5 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V5; END IF;
    IF V6 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V6; END IF;
    IF V7 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V7; END IF;
    IF V8 IS NOT NULL THEN COUNT=COUNT+1; TOTAL=TOTAL+V8; END IF;
    RETURN TOTAL/COUNT;
    EXCEPTION WHEN DIVISION_BY_ZERO THEN RETURN NULL;
END
$FUNCTION$ LANGUAGE PLPGSQL;
3
Bob S