extract lowest number before and after slashmark in sql - sql

Question

I have a large dataset of measurements, stored in a free text field. I'm needing to extract the lowest systolic amount (value to left of slash) and lowest diastolic amount (value to right of slash). I've included a sample dataset below... As you can see, some of the records, like #2, are simple, but others are complex. Is there anyway to do this in sql or teradata? Any suggestions are appreciated!
record 1 lt 90/50 rt 128/88
record 2 left arm regular cuff 144/100
record 3 156/72;134/82
record 4 204/127, 189/122, 196/121

Answer 1

What's your TD release?
In TD14 there's a StrTok_Split_to_Table/StrTok function:
DROP TABLE tab;
CREATE TABLE tab (id INT, TEXT VARCHAR(200));
INSERT INTO tab(1,'lt 90/50 rt 128/88');
INSERT INTO tab(2,'left arm regular cuff 144/100');
INSERT INTO tab(3,'156/72;134/82');
INSERT INTO tab(4,'204/127, 189/122, 196/121');
SELECT id,
MIN(CAST(STRTOK(token,'/',1) AS INT)) AS systolic,
MIN(CAST(STRTOK(token,'/',2) AS INT)) AS diastolic
FROM
TABLE (STRTOK_SPLIT_TO_TABLE(tab.id, tab.TEXT, ' ,;')
RETURNS (id INT, tokennum INTEGER, token VARCHAR(256) CHARACTER SET UNICODE)
) AS dt
WHERE token LIKE '%/%'
GROUP BY 1
ORDER BY 1,2;
You have to check for any additional delimiters beside ' ,;' otherwise the CAST to INT will fail.
If your release is pre-TD14 the STRTOK_SPLIT_TO_TABLE can probably be replaced by a way more complicated recursive query. How many rows exist in that table and how large is the text column defined?
Edit:
This is a quick&dirty recursive query, assuming blood pressure for living people is never single or four digits :-)
WITH RECURSIVE cte
(id,
pos,
remaining,
token
) AS (
SELECT
id,
POSITION('/' IN TEXT) AS pos,
SUBSTRING(TEXT FROM pos +4) AS remaining,
TRIM(BOTH ',' FROM (TRIM(BOTH ';' FROM (TRIM(BOTH ' ' FROM (SUBSTRING(TEXT FROM pos -3 FOR 7))))))) AS token
FROM tab
WHERE POSITION('/' IN TEXT) > 0
UNION ALL
SELECT
id,
POSITION('/' IN remaining) AS newpos,
SUBSTRING(remaining FROM newpos +4) AS remaining,
TRIM(BOTH ',' FROM (TRIM(BOTH ';' FROM (TRIM(BOTH ' ' FROM (SUBSTRING(remaining FROM newpos -3 FOR 7))))))) AS token
FROM cte
WHERE POSITION('/' IN remaining) > 0
)
SELECT id,
MIN(CAST(SUBSTRING(token FROM 1 FOR POSITION('/' IN token) -1) AS INT)) AS stolic,
MIN(CAST(SUBSTRING(token FROM POSITION('/' IN token) +1) AS INT)) AS diasystolic
FROM cte
GROUP BY 1
Btw, both queries will fail if there are no numbers before/after the slash