How to pull a max value/first value for duplicates in a group in a query?

Question

Hi everybody,
[Oracle 10g]
I'm working with two tables, tblPatient and tblProgressNotes. The fields I'm working with are:
<pre>
<li>tblPatient.PatientID</li>
<li>tblPatient.EpisodeNumber (this tracks the number of hospital visits)</li>
<li>tblPatient.DischargeDate</li>
<li>tblProgressNotes.Height</li>
<li>tblProgressNotes.Weight</li>
<li>tblProgressNotes.Girth</li>
<li>tblProgressNotes.EntryDate</li>
<li>tblProgressNotes.EntryTime</li>
</pre>
From the fields above, I need to pull the most recent episode for each patient and each unique entry date so I can collect the height, weight, girth, and chart the plots on a graph. The problem I'm running into, though, is that there may be multiple entries on a given day. I can get the most recent episode for each patient with a "WHERE tblPatient.DischargeDate Is Null," but I'm not sure how to pull just the unique dates for each patient.
For instance, if I have the following:
<pre>
     <u>PatientID EpisodeNumber EntryDate EntryTime Height Weight Girth</u>
1 1 01.01.13 1:03 PM 66 185 35.5
1 1 01.01.13 7:18 PM 66 184 36
1 1 01.07.13 8:57 AM 66 190 36
1 1 01.07.13 11:32 AM 66 189 35.5
</pre>
For the first two records, I only want to return one record on 01.01.13. What I would really like, if there is more than one entry on a single day, is to take the average of the height, weight, and girth entries for that day and return a single record (I don't need the time entries, but I included them initially for testing). So, this is what my desired output would look like:
<pre>
     <u>PatientID EpisodeNumber EntryDate Height Weight Girth</u>
1 1 01.01.13 66 184.5 35.75
1 1 01.07.13 66 189.5 35.75
</pre>
If it's not possible to write a query like the above, then I would like to take the first entry for each day where there are multiple entries on that day. So, this would be the desired output (I included the EntryTime again so you can compare to the original example):
<pre>
     <u>PatientID EpisodeNumber EntryDate EntryTime Height Weight Girth</u>
1 1 01.01.13 1:03 PM 66 185 35.5
1 1 01.07.13 8:57 AM 66 190 36
</pre>
Thanks for your help.

Answer 1

Hi,
987019 wrote:
Here's some sample data:
CREATE TABLE TBLPATIENT
PATID VARCHAR2 (20),
EPISODE_NUMBER DOUBLE,
DATE_OF_DISCHARGE DATE
CREATE TABLE TBLPROGRESSNOTES
PATID VARCHAR2 (20),
EPISODE_NUMBER DOUBLE,
DATA_ENTRY_DATE DATE,
GIRTH VARCHAR2 (5),
HEIGHT DOUBLE,
WEIGHT DOUBLE,
Thanks. I had to make some changes to get it to run:
CREATE TABLE TBLPATIENT
        PATID               VARCHAR2 (20),
        EPISODE_NUMBER           BINARY_DOUBLE,     -- There's no DOUBLE data type in SQL
        DATE_OF_DISCHARGE      DATE
DROP TABLE     tblprogressnotes;
CREATE TABLE TBLPROGRESSNOTES
        PATID          VARCHAR2 (20),
        EPISODE_NUMBER      NUMBER,          -- Most people use NUMBER for all numeric types
        ENTRY_DATE      DATE,          -- DATA_entry date is a good name, too, just be consistent
        GIRTH           NUMBER,          -- Can't average VARCHAR2s
        HEIGHT          NUMBER,
        WEIGHT           NUMBER          -- no comma here
INSERT INTO TBLPATIENT VALUES (1, 1);
INSERT INTO TBLPATIENT VALUES (2, 1);
// For the first 3 records, the height stays the same, but the girth and weight values are variable on the same day
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/01/2013 00:00:00', 'MM/DD/YYYY HH:MM:SS'), 36, 66, 184);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/01/2013 00:00:00', 'MM/DD/YYYY HH:MM:SS'), 35.5, 66, 185);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/01/2013 00:00:00', 'MM/DD/YYYY HH:MM:SS'), 35, 66, 184.5);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/18/2013 00:00:00', 'MM/DD/YYYY HH:MM:SS'), 36, 66, 187);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/31/2013 00:00:00', 'MM/DD/YYYY HH:MM:SS'), 36.5, 66, 190);
// For the last 3 records, the girth and height stay the same, but the weight is variable on the same day.
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/03/2013 00:00:00', 'MM/DD/YYYY HH:MM:SS'), 32, 66, 137.5);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/08/2013 00:00:00', 'MM/DD/YYYY HH:MM:SS'), 32.5, 66, 138);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/19/2013 00:00:00', 'MM/DD/YYYY HH:MM:SS'), 31, 66, 134);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/19/2013 00:00:00', 'MM/DD/YYYY HH:MM:SS'), 31, 66, 133.5);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/19/2013 00:00:00', 'MM/DD/YYYY HH:MM:SS'), 31, 66, 134.5);
INSERT INTO TBLPATIENT VALUES (1, 1, NULL);
-- If the table has 3 columns,     ^^^^^^  INSERT 3 values (or say which columns you're INSERTing)
INSERT INTO TBLPATIENT VALUES (2, 1, NULL);
// For the first 3 records, the height stays the same, but the girth and weight values are variable on the same day
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/01/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 36, 66, 184);
--                                                             MM = month  ^^            ^^ MI = minutes
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/01/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 35.5, 66, 185);
--                                                         Hour 00  ^^  not valid for HH   ^^^^  use HH24 instead
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/01/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 35, 66, 184.5);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/18/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 36, 66, 187);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/31/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 36.5, 66, 190);
// For the last 3 records, the girth and height stay the same, but the weight is variable on the same day.
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/03/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 32, 66, 137.5);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/08/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 32.5, 66, 138);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/19/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 31, 66, 134);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/19/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 31, 66, 133.5);
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/19/2013 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 31, 66, 134.5);This seems to be different from the sample data you posted earlier. You didn't say what results you want from this data, so I don't know if this gets them or not:
SELECT
        P.PATID,
        P.EPISODE_NUMBER,
        P.DATE_OF_DISCHARGE,
        M.ENTRY_DATE,
--      M.ENTRY_TIME,          -- Not needed (not present in simplified sample data, anyway)
        AVG (M.GIRTH)     AS avg_girth,             -- AVG added
        AVG (M.HEIGHT)     AS avg_height,
        AVG (M.WEIGHT)     AS avg_weight
FROM
        TBLPATIENT P LEFT OUTER JOIN
        TBLPROGRESSNOTES M ON
                (P.PATID = M.PATID) AND
                (P.EPISODE_NUMBER = M.EPISODE_NUMBER)
WHERE
        P.DATE_OF_DISCHARGE IS NULL AND
        M.ENTRY_DATE BETWEEN (SYSDATE - 60) AND SYSDATE AND
        M.HEIGHT  != 0 AND        -- This site won't display the other inequlaity operator
        M.WEIGHT  != 0
GROUP BY               -- GROUP BY clause added
        P.PATID,          -- Includes all columns from the SELECT clause that
        P.EPISODE_NUMBER,     --      are not aggregated
        P.DATE_OF_DISCHARGE,
        M.ENTRY_DATE
ORDER BY
        P.PATID,          -- No column called patIENTid
        M.ENTRY_DATE
-- ,    M.ENTRY_TIME
;As you can see, it's very close to what you posted, and to what I suggested earlier: use AVG on the columns that you want to average, and GROUP BY the other columns. I marked all the places I changed with in-line comments.
Since the hours, mintues and seconds of entry_date are always 00:00:00, then there's no need to use TRUNC (entry_date). Using it unnecessaily won't change the results, it will only waste a little time.
By the way, if you omit the hours, minutes and seconds in TO_DATE, they default to 00:00:00, so you could make the insert statements a little simpler like this:
INSERT INTO TBLPROGRESSNOTES VALUES (1, 1, TO_DATE('01/01/2013', 'MM/DD/YYYY'), 36, 66, 184);Output fro the query above:
`     EPISODE
PATID _NUMBER DATE_OF_DI ENTRY_DATE  AVG_GIRTH AVG_HEIGHT AVG_WEIGHT
1           1            01/01/2013       35.5         66      184.5
1           1            01/03/2013         32         66      137.5
1           1            01/08/2013       32.5         66        138
1           1            01/18/2013         36         66        187
1           1            01/19/2013         31         66        134
1           1            01/31/2013       36.5         66        190