Compare string in database - mysql

Question

I have these entries in database.
Numbers at the end are versions, i.e 10.0, 9.1, 9.0. I need to compare the entries and I used a query like,
select * from Fault_Profile where PROFILE_NAME < 'DEFAULT_9.1';
But the entries are comapred like string, and returns values with 10.0 (I know it is obivous).
But is there any way using sql queries to extract number out of the string and compare it like numbers.
NOTE : This is old design in my project can't change schema can't change values.

Answer 1

You can use SUBSTR() then retype to DOUBLE
SELECT *
FROM Fault_Profile
WHERE SUBSTRING(PROFILE_NAME, 9) < 9.1;

Answer 2

May not be an efficient one but you can try something like below, which will return only the part after _. i.e, 10.0, 9.1, 9.0
select
substring('Default_9.0',
locate('_','Default_9.0')+1,
(length('Default_9.0') - locate('_','Default_9.0')))
So, per your query it should be
select *
from Fault_Profile
where
substring(PROFILE_NAME,
locate('_',PROFILE_NAME)+1,
(length(PROFILE_NAME) - locate('_',PROFILE_NAME))) < 9.1

Answer 3

CREATE FUNCTION PROFILE_NAME_VERSION
(
-- Add the parameters for the function here
#PROFILE_NAME nvarchar(100)
)
RETURNS float
AS
BEGIN
-- Declare the return variable here
DECLARE #ResultVar float
SET #ResultVar=CAST(REPLACE(#PROFILE_NAME,'DEFAULT_','') as float)
RETURN #ResultVar
END
GO
select * from Fault_Profile where dbo.PROFILE_NAME_VERSION(PROFILE_NAME) < 9.1
Replace the size of the function parameter for match your size

Answer 4

you can use REPLACE too
SELECT *
FROM Fault_Profile
where REPLACE(PROFILE_NAME, 'Default_','')*1 < 9.1

Answer 5

SQL Fiddle:
SELECT *
FROM Fault_Profile
WHERE CAST(RIGHT(PROFILE_NAME, CHARACTER_LENGTH(PROFILE_NAME) - INSTR(PROFILE_NAME, '_')) AS DECIMAL(3,1)) < 9.1
ORDER BY CAST(RIGHT(PROFILE_NAME, CHARACTER_LENGTH(PROFILE_NAME) - INSTR(PROFILE_NAME, '_')) AS DECIMAL(3,1));
Or if this looks better to you (SQL Fiddle):
SELECT m.PROFILE_NAME, m.ALARM_CLASS FROM
(
SELECT *,
CAST(RIGHT(PROFILE_NAME, CHARACTER_LENGTH(PROFILE_NAME) - INSTR(PROFILE_NAME, '_')) AS DECIMAL(3,1)) AS version
FROM Fault_Profile f
) AS m
WHERE m.version < 9.1
ORDER BY m.version, m.ALARM_CLASS
The above query does assume that the characters after the _ will be the numeric version number. However, you can have as many characters as you need in front of the _. So for instance it will still work with; Beta_9.0 and Production_10.1.