is there any way apply math formula from stored string in Oracle and or MySQL?
col1 | col2 | formula
---------------------
2 | 2 | col1*col2
2 | 3 | col1+col2
SELECT * from tbl
result:
col1 | col2 | formula
---------------------
2 | 2 | 4
2 | 3 | 5
edit: for each row another formula
I think what you're saying is you want to have the database parse the formula string. For example, for Oracle you could
Add a column to the table to contain the result
Run an update statement which would call a PL/SQL function with the values of the columns in the table and the text of the formula
update {table} set formula_result = fn_calc_result (col1, col2, formula_column);
The PL/SQL function would create a string by replacing the "col1" and "col2" and so forth with the actual values of those columns. You can do that with regular expresions, as long as the formulas are consistently written.
Then use
execute immediate 'select '||{formula}||' from dual' into v_return;
return v_return;
to calculate the result and return it.
Of course, you could also write your own parser. If you decide to go that way, don't forget to handle operation precedence, parentheses, and so forth.
I think you want a virtual column. See here for excellent article on its setup and use.
you may do it via a PL/SQL script that you can trigger automcatically when inserting the data.
See http://en.wikipedia.org/wiki/PL/SQL
PL/SQL is a kind of program that executes in the database itself. It's quite easy to do.
Related
Best way to store a dynamic expression in a table for each row for a searching module.
The expression is dynamic and can have multiple fields which are being compared.
I considered creating a separate column for each type of field and fattening out complex nested logic by getting all possible combinations using dnf and storing them in my table. The disadvantages of doing that is for every new logic and expression, a new column has to be created which would lead to a large table which has too many NULLS in it and also adding a new column would take time & refactoring(we are talking about more than 800 columns here).
The alternate approach which I think would work better is below->
I want to discuss if there are better way to this, and if not, how can we improve and achieve the below suggested approach.
| id | expression | diagnosis |
|------|------------------------------------------------|-------------|
| 1 |`p.age>12 and p.gender==Male` | diseaseA |
| 2 |`p.age>50 and p.bp>20` | diseaseB |
| 3 |`p.age<20 and p.bp<20` | diseaseC |
| 4 |`p.age<30 and p.age>20 and (p.bp<30 or p.bp>50)`| diseaseD |
I want to search in this table, for a patient p with certain properties (age=*something*,bp=*something*,etc).
The resulting rows should return all rows which satisfy the expression and also rows which partially match the expression(i.e the rows which are using properties not supplied in the search criteria).
For example for a search for patient p(age=22,bp=15), the search result should be
| id | disease |
|------|-------------|
| 1 | diseaseA |
| 3 | diseaseC |
| 4 | diseaseD |
Since I am new to SQL, the (newbie) way I think I can do this is
First get all the rows(in-memory would be costly, lets discuss what is best possible way to execute the below said functionality in point 2 row-by-row)
Then row-by-row transform the expression to a logical executable expression(which is later executed using eval) using regex matching & replacement(I hope there is a better way than this) for the search criteria(i.e. substituting the patient details) [in my example for the 2nd row, the expression p.age>50 and p.bp>20 gets converted to "22>50 && 15>20"]
All the rows for which the result of transforming & executing the result was true(or partially matched) should be returned.
The language is not an issue as I would be starting this project from scratch and can use any language
I can answer for MySQL.
First of all, you'll have to write all of your sql code inside sql procedure.
Generally you are interestedin dynamic SQL
https://dev.mysql.com/doc/refman/5.7/en/sql-syntax-prepared-statements.html
So a straight-forward approach is to open a a cursor for your table with expressions and for each expression replace p.age with it's actual value and then execute dynamic SQL. (select 22 > 50 and 15 > 20)
Another approach is to loop through expression table (open cursor for it) and as you probably have patient id (not only it's field values) just generate normal sql that selects from patient table (select patient_id from patients where [expression_from_expression_table] and patient_id = [your_known_patient_id])
And the third one that I can imagine is generating a big single query from whole expression table
select group_concat(concat('if(', expression, ',"', diagnosis, '", "") as ', diagnosis) separator ',') from expressions into somevar;
and then doing replace of p.* with actual values and executing second query:
set somevar = replace(somevar, 'p.age', '15');
...
#qry = concat('select ', somevar);
PREPARE qry FROM #qry;
EXECUTE qry;
The third approach is fastest to my mind but will require aditional work on client as you will recieve diagnosis as columns, not as rows.
But hope you get the general idea.
I have a table lake that :
TABLE A
id | arithmetic | column2
1 |{id1}/{id2} | bla bla
2 |{id3}+{id5}*1000| other bla bla
3 | ...
another table - TABLE B
id | values |
1 | 4 |
2 | 7 |
3 | 0,25 |
...
I wanna take a QUERY that execute the arithmetic operator in TABLE A using values of TABLE B .
Considering I already have managed to make the replacement of the codes by the figures in table B , they are as string is read as a string and not as a number, if I use a CONVERT ( arithmetic , unsigned integer) , it does not execute the expression but yes transforms the numbers encontraods to the first mathematical operator .
I trying to use convert(#arithmetic, unsigned integer), but not sucessfull.
Like a example in a simple select :
Select '5+2', results '5+2';
but if I use select 5+2 , results 7.
therefore if I use select convert ( '5+2', unsigned integer); , results 5 ( read until the first character not mathematical).
In short words : read and execute a math expression wrote inside a field?
General notes
First thing first, make sure that you're not in the middle of XY-problem with your architecture. DBMS should not handle such logic solution in general, as the logic is not part of data, it should be part of application. However, even in application, you should avoid run-time evaluation as it in most cases not safe and unpredictable (thus, source from any kind of problems).
Solution with DBMS
While I would not recommend to go this way - with evaluation of expression on run-time, it is still possible with prepared statements, like:
SET #expr:=(
SELECT
GROUP_CONCAT(CONCAT('SELECT ', arithmetic, ' AS expr') SEPARATOR ' UNION ALL ') AS expr
FROM tableA
);
PREPARE execSelect FROM #expr;
EXECUTE execSelect;
Working fiddle is here. I may even imagine values substitution, but I would not recommend to go this way. If you really need this, then, most probably, something is wrong with architecture breakdown, since your data within SQL needs to hold some logic - and that's the goal for your application, not for your database.
I have a simple MySQL table made up of words and an associated number. The numbers are unique for each word. I want to find the first word whose index is larger than a given number. As an example:
-----------------------
| WORD: | F_INDEX: |
|---------------------|
| a | 5 |
| cat | 12 |
| bat | 4002 |
-----------------------
If I was given the number "9" I would want "cat" returned, as it is the first word whose index is larger than 9.
I know that I can get a full list of sorted rows by querying:
SELECT * FROM table_name ORDER BY f_index;
But would, instead, like to make a MySQL query that does this. (The confusion lies in the fact that I'm unsure as to how to keep track of the current row in my query). I know can loop with something like this:
CREATE PROCEDURE looper(desired_index INT)
BEGIN
DECLARE current_index int DEFAULT 0
// Loop here, setting current_index to whatever the next rows index is,
// then do a comparison to check it to our desired_index, breaking out
// if it is greater.
END;
Any help would be greatly appreciated.
Try this:
SELECT t.word
, t.f_index
FROM table_name t
WHERE t.f_index > 9
ORDER
BY t.f_index
LIMIT 1
It is much more efficient to have the database return the row you need, than it is to pull a whole bunch of rows and figure out which one you need.
For best performance of this query, you will want an index ON table_name (f_index,word).
Why don't you just use MYSQL statement to retrieve the first item you found from f_index where the f_index is greater than the value your pass in.
For example :
select word from table_name
where f_index > desired_index
order by f_index
limit 1
I have fields in mytable tab1:
col1 | col2 | id
--------------------------
1,2,3 | 2,3,4,5 | a1
6,7,8,9 | 2,9,11 | a2
i want to pass this fields to my stored procedure input like where col1 in ('1,2') and col2 in ('3,4');
but it is not working ..
Something like this should work:
SELECT t.* FROM tab1 t
WHERE 1 IN (t.col1) AND 2 IN (t.col1) ...
AND 3 IN (t.col2) AND 4 IN (t.col2) ...
You would need to build up your query based on the inputs to your stored procedure, but otherwise this should work for you. Post your current proc?
EDIT
The find_in_set function will also work for you, but you will still have to split your inputs and call it once per number passed to the proc (i.e. the first parameter to FIND_IN_SET cannot be a comma separated list). Reference here: http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_find-in-set
Postgresql 9.2 DB which automatically collects data from various machines.
The DB stores all the data including the machine id, the firmware, the manufacturer id etc as well as the actual result data. In one stored field (varchar) there are 5 sub fields which are separated by the ^ character.
ACT18!!!8246-EN-2.00013151!1^7.00^F5260046959^H1P1O1R1C1Q1L1^1 (Machine 1)
The order of this data seems to vary from one machine to another. Eg machine 1 2 and 3. The string above shows the firmware version, in this case "7.0" and it appears in sub-field 2. However, another machine sends the data in a different sub-field - in this case sub-field 3 and the value is "1"
BACT/ALERT^A.00^1^^ (Machine 2)
I want to store the values "7.0" and "1" in a different field in a separate table using a CREATE TRIGGER t_machine_id AFTER INSERT function where I can choose which sub-field is used depending on the machine the data has come from.
Is split_part the best function to do this? Can anyone supply an example code that will do this? I can't find anything in the documentation.
You need to (a) split the data using something like regexp_split_to_table then (b) match which parts are which using some criteria, since you don't have field position-order to rely on. Right now I don't see any reliable rule to decide what's the firmware version and what's the machine number; you can't really say where field <> machine_number because if machine 1 had firmware version 1 you'd get no results.
Given dummy data:
CREATE TABLE machine_info(data text, machine_no integer);
INSERT INTO machine_info(data,machine_no) (VALUES
('ACT18!!!8246-EN-2.00013151!1^7.00^F5260046959^H1P1O1R1C1Q1L1^1',1),
('BACT/ALERT^A.00^1^^',2)
);
Something like:
SELECT machine_no, regexp_split_to_table(data,'\^')
FROM machine_info;
will give you a table of split data elements with machine number, but then you need to decide which fields are which:
machine_no | regexp_split_to_table
------------+------------------------------
1 | ACT18!!!8246-EN-2.00013151!1
1 | 7.00
1 | F5260046959
1 | H1P1O1R1C1Q1L1
1 | 1
2 | BACT/ALERT
2 | A.00
2 | 1
2 |
2 |
(10 rows)
You may find the output of substituting regexp_split_to_array more useful, depending on whether you can get any useful info from field order and how you intend to process the data.
regress=# SELECT machine_no, regexp_split_to_array(data,'\^')
FROM machine_info;
machine_no | regexp_split_to_array
------------+------------------------------------------------------------------
1 | {ACT18!!!8246-EN-2.00013151!1,7.00,F5260046959,H1P1O1R1C1Q1L1,1}
2 | {BACT/ALERT,A.00,1,"",""}
(2 rows)
Say there are two firmware versions; version 1 sends code^blah^fwvers^^ and version 2 and higher sends code^fwvers^blah^blah2^machineno. You can then differentiate between the two because you know that version 1 leaves the last two fields blank:
SELECT
machine_no,
CASE WHEN info_arr[4:5] = ARRAY['',''] THEN info_arr[3] ELSE info_arr[2] END AS fw_vers
FROM (
SELECT machine_no, regexp_split_to_array(data,'\^')
FROM machine_info
) string_parts(machine_no, info_arr);
results:
machine_no | fw_vers
------------+---------
1 | 7.00
2 | 1
(2 rows)
Of course, you've only provided two sample data, so the real matching rules are likely to be more complex. Consider writing an SQL function to extract the desired field(s) and return them from the array passed.