Extracting numerical values from mySQL column string value - mysql

Question

I have a "person" column in a mySQL database that represents the age and weight of a person as a string separated by a comma.
Example:
"24,175"
I want to be able to separate and extract those values and cast them as numbers.
Example: turn "24,175" to
24 as age
175 as weight
So that I can write a query similar to the following
SELECT person
FROM TABLE
WHERE age>140 OR weight>1000
I want to be able to check for values that are not possible. i.e age>140 OR weight >1000.
I cannot modify the table/environment I'm working with
I only have access to queries.
I'm thinking about solving it this way
find the index where the comma exists. CHARINDEX(',',person)
Split the string into substrings using LEFT , RIGHT, CAST and CHARINDEX(',',person)
Cast age substring and weight substring to numbers using CAST(age AS INT) CAST(weight AS INT)
SELECT person
FROM TABLE
WHERE CAST(LEFT(person,CHARINDEX(',',person) AS INT)>150 OR CAST(RIGHT(person,CHARINDEX(',',person) AS INT) >1000
If I did anything wrong please correct me.
Are all the functions usable/supported by mySQL? (RIGHT, LEFT, CHARINDEX) Will this work?
Exception: Another value for this column could be "unknown". Will this cause errors if we're trying to check for the index of , if it doesn't exist in the string? Is there a way to include "unknown" cases in the result and have it output a message of "error, person not recognized"

Answer 1

you can also split is with SUBSTR_INDEX like this:
MariaDB [yourschema]> SELECT * FROM spliit;
+----+--------+
| id | d |
+----+--------+
| 1 | 24,175 |
+----+--------+
1 row in set (0.03 sec)
MariaDB [yourschema]> SELECT
-> SUBSTRING_INDEX(d, ',', 1) AS age
-> , SUBSTRING_INDEX(d, ',', -1) AS weight
->
-> FROM spliit;
+------+--------+
| age | weight |
+------+--------+
| 24 | 175 |
+------+--------+
1 row in set (0.00 sec)
MariaDB [yourschema]>
sample
yes, you can direct calculate with it in MySQL
MariaDB [yourschema]> SELECT
-> SUBSTRING_INDEX(d, ',', 1) + 2 AS age
-> , SUBSTRING_INDEX(d, ',', 1) * 12 AS `month`
-> , SUBSTRING_INDEX(d, ',', -1) + 3 AS weight
-> FROM spliit;
+------+-------+--------+
| age | month | weight |
+------+-------+--------+
| 26 | 288 | 178 |
+------+-------+--------+
1 row in set, 1 warning (0.03 sec)
MariaDB [yourschema]>

Answer 2

SELECT person
FROM TABLE
WHERE CAST(LEFT(person,LOCATE(',',person) AS INTEGER)>150 OR CAST(RIGHT(person,(LOCATE(',',person)+1) AS INTEGER) >1000
Instead of Char index use LOCATE im MqSQL
Also note the CAST function

Answer 3

You also can use VIRTUAL PERSITENT COLUMNS that calculate the fields automatis and you can also use a INDEX on each substr / Integer.
sample
MariaDB [yourschema]> CREATE TABLE `splitit` (
-> `id` INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
-> `d` VARCHAR(32) DEFAULT NULL,
-> age INT(11) AS (SUBSTRING_INDEX(d, ',', 1)) PERSISTENT,
-> weight INT(5) AS (SUBSTRING_INDEX(d, ',', -1)) PERSISTENT,
-> PRIMARY KEY (`id`),
-> INDEX idx_age (age),
-> INDEX idx_weight (weight)
-> ) ENGINE=INNODB DEFAULT CHARSET=utf8;
Query OK, 0 rows affected (0.79 sec)
MariaDB [yourschema]> INSERT INTO splitit (d) VALUES ('11,234'),('2,66'),('5,2');
Query OK, 3 rows affected (0.06 sec)
Records: 3 Duplicates: 0 Warnings: 0
MariaDB [yourschema]> SELECT * FROM splitit;
+----+--------+------+--------+
| id | d | age | weight |
+----+--------+------+--------+
| 1 | 11,234 | 11 | 234 |
| 2 | 2,66 | 2 | 66 |
| 3 | 5,2 | 5 | 2 |
+----+--------+------+--------+
3 rows in set (0.00 sec)
MariaDB [yourschema]>

Answer 4

You can do this all in the where clause:
where substring_index(person, ',', 1) + 0 > 140 or
substring_index(person, ',' -1) + 0 > 1000
Note that the + 0 does an silent conversion to integers. And, substring_index()is much more convenient than the functions in SQL Server.
You can readily incorporate this logic into a view:
create view v_table as
select t.*,
substring_index(person, ',', 1) + 0 as age,
substring_index(person, ',' -1) + 0 as weight
from table t;
If you want to filter out bad values within the view, you can use a MySQL extension and add:
having age > 140 or weight > 1000
after the from clause.