Dynamic query based of business rules - tsql

Question

I hope you are well.
I need your help and advice on a repetitive task that I would like to automate.
Every month my manager asks me to run a series of SQL queries based on the same table and columns.
I thought I could create a rules table that would allow him to create his own queries
So I created this rules table like this:
Based on this table I would like to successively execute 3 queries.
The first query is for the rule '+NET 3 or More' and the query is like that:
SELECT * FROM Table Where
([QuestionCode] = 'HSZ' AND ResponseCode = 3)
OR ([QuestionCode] = 'HSZ' AND ResponseCode = 4)
The Second Query is for the Rule 'Age Between 25-35' and the query is like that:
SELECT * FROM Table Where
([QuestionCode] = 'RS2' AND ResponseCode >= 25)
AND ([QuestionCode] = 'RS2' AND ResponseCode < 35)
The 3rd query is for the rule 'CHN' and 'HSZ' and the query is like that:
SELECT * FROM Table Where
([QuestionCode] = 'CHN' AND ResponseCode = 5)
AND ([QuestionCode] = 'HSZ' AND ResponseCode = 1)
I would like your opinion on this solution and especially have your help to create this dynamic query
Here is the script to create the rule table:
WITH CTE AS
(
SELECT RuleId = 1
, NetQuestionCode = '+NET 3 or More'
, QuestionCategory = 'HSZ'
, QuestionCode = 'HSZ'
, ResponseOperator = '='
, ResponseCode = '3'
, RuleOrder = '1'
, CategoryRule = 'OR'
UNION ALL
SELECT RuleId = 1
, NetQuestionCode = '+NET 3 or More'
, QuestionCategory = 'HSZ'
, QuestionCode = 'HSZ'
,ResponseOperator = '='
, ResponseCode = '4'
, RuleOrder = '2'
, CategoryRule = 'OR'
UNION ALL
SELECT RuleId = 2
, NetQuestionCode = 'Age Between 25-35'
, QuestionCategory = 'RS2'
, QuestionCode = 'RS2'
,ResponseOperator = '>='
, ResponseCode = '25'
, RuleOrder = '1'
, CategoryRule = 'and'
UNION ALL
SELECT RuleId = 2
, NetQuestionCode = 'Age Between 25-35'
, QuestionCategory = 'RS2'
, QuestionCode = 'RS2'
,ResponseOperator = '<'
, ResponseCode = '35'
, RuleOrder = '2'
, CategoryRule = 'and'
UNION ALL
SELECT RuleId = 3
, NetQuestionCode = 'CHN AND HSZ'
, QuestionCategory = 'CHN'
, QuestionCode = 'CHN'
,ResponseOperator = '='
, ResponseCode = '5'
, RuleOrder = '1'
, CategoryRule = 'and'
UNION ALL
SELECT RuleId = 3
, NetQuestionCode = 'CHN AND HSZ'
, QuestionCategory = 'CHN'
, QuestionCode = 'HSZ'
,ResponseOperator = '='
, ResponseCode = '1'
, RuleOrder = '2'
, CategoryRule = 'and'
)
SELECT *
Into [dbo].[Rules_Parameters]
FROM CTE
Thank you for your help.

Answer 1

Try this out, I based it on your CTE, I added more common table expressions, to build the dynamic part of the WHERE, then used another one to group the conditions for the same rule based on the operator and finally move it to a variable that will be used with the dynamic sql.
declare #DynamicQuery nvarchar(max)=''
; WITH CTE AS
(
SELECT RuleId = 1
, NetQuestionCode = '+NET 3 or More'
, QuestionCategory = 'HSZ'
, QuestionCode = 'HSZ'
, ResponseOperator = '='
, ResponseCode = '3'
, RuleOrder = '1'
, CategoryRule = 'OR'
UNION ALL
SELECT RuleId = 1
, NetQuestionCode = '+NET 3 or More'
, QuestionCategory = 'HSZ'
, QuestionCode = 'HSZ'
,ResponseOperator = '='
, ResponseCode = '4'
, RuleOrder = '2'
, CategoryRule = 'OR'
UNION ALL
SELECT RuleId = 2
, NetQuestionCode = 'Age Between 25-35'
, QuestionCategory = 'RS2'
, QuestionCode = 'RS2'
,ResponseOperator = '>='
, ResponseCode = '25'
, RuleOrder = '1'
, CategoryRule = 'and'
UNION ALL
SELECT RuleId = 2
, NetQuestionCode = 'Age Between 25-35'
, QuestionCategory = 'RS2'
, QuestionCode = 'RS2'
,ResponseOperator = '<'
, ResponseCode = '35'
, RuleOrder = '2'
, CategoryRule = 'and'
UNION ALL
SELECT RuleId = 3
, NetQuestionCode = 'CHN AND HSZ'
, QuestionCategory = 'CHN'
, QuestionCode = 'CHN'
,ResponseOperator = '='
, ResponseCode = '5'
, RuleOrder = '1'
, CategoryRule = 'and'
UNION ALL
SELECT RuleId = 3
, NetQuestionCode = 'CHN AND HSZ'
, QuestionCategory = 'CHN'
, QuestionCode = 'HSZ'
,ResponseOperator = '='
, ResponseCode = '1'
, RuleOrder = '2'
, CategoryRule = 'and'
),WhereCondition as (
SELECT *,'([QuestionCode] = '''+QuestionCode+''' AND ResponseCode '+ResponseOperator+' '+ResponseCode+')' [Condition] FROM CTE
),G as (
select *,cast(Condition as varchar(max)) WhereAll from WhereCondition where RuleOrder=1
union all
select c.*,WhereAll+' '+c.CategoryRule+' '+c.Condition from G
inner join WhereCondition c on c.RuleOrder=(G.RuleOrder+1) and c.RuleId=G.RuleId
),qq as (
select top(3) 'SELECT * FROM Table Where '+WhereAll+';' [q] from G order by RuleOrder desc
)
select #DynamicQuery=#DynamicQuery+q from qq
EXECUTE sp_executesql #DynamicQuery
or if you want it from the [Rules_Parameters], the change is as below:-
;with WhereCondition as (
SELECT *,'([QuestionCode] = '''+QuestionCode+''' AND ResponseCode '+ResponseOperator+' '+ResponseCode+')' [Condition] FROM [dbo].[Rules_Parameters]
),G as (
select *,cast(Condition as varchar(max)) WhereAll from WhereCondition where RuleOrder=1
union all
select c.*,WhereAll+' '+c.CategoryRule+' '+c.Condition from G
inner join WhereCondition c on c.RuleOrder=(G.RuleOrder+1) and c.RuleId=G.RuleId
),qq as (
select top(3) 'SELECT * FROM Table Where '+WhereAll+';' [q] from G order by RuleOrder desc
)
select #DynamicQuery=#DynamicQuery+q from qq
EXECUTE sp_executesql #DynamicQuery
In either way the #DynamicQuery variable will contain the below:-
SELECT * FROM Table Where ([QuestionCode] = 'CHN' AND ResponseCode = 5) and ([QuestionCode] = 'HSZ' AND ResponseCode = 1);SELECT * FROM Table Where ([QuestionCode] = 'RS2' AND ResponseCode >= 25) and ([QuestionCode] = 'RS2' AND ResponseCode < 35);SELECT * FROM Table Where ([QuestionCode] = 'HSZ' AND ResponseCode = 3) OR ([QuestionCode] = 'HSZ' AND ResponseCode = 4);
Hope this is what you want.
Note: I did not put any validations, for example ResponseOperator may have an operator that will not work and break the query , etc.
Note: I did not use STRING_AGG as you did not mention your sql database version.