Incorrect syntax of dynamic sql query - sql

Question

I need help with body of dynamic sql query.
Now, my query like this
declare #query nvarchar(MAX), #preSubQuery nvarchar(200), #subQueryTxt nvarchar(500), #postSubQuery nvarchar(100);
set #postSubQuery = N' ELSE 0 END))'
set #preSubQuery = N' ,SUM(( CASE DATEDIFF(WEEK, pay.dateCreate, back.dateCreate) WHEN ';
set #subQueryTxt = N' THEN
CASE
WHEN ...
THEN 0
WHEN ...
THEN ...
ELSE
CASE
WHEN ...
THEN ...
WHEN ...
THEN ...
ELSE 0
END
END ';
select #query = N'select DATEPART(ISO_WEEK, pay.dateCreate) backWeek ,SUM(pay_and_back.PayActualPrincipalAmt) AS TotalAmount' +
+ N' #preSubQuery' + N' 0' + ' #subQueryTxt' + ' #postSubQuery'
+ N' #preSubQuery' + N' 1' + ' #subQueryTxt' + ' #postSubQuery'
+ N' #preSubQuery' + N' 2' + ' #subQueryTxt' + ' #postSubQuery'
....
+ N' #preSubQuery' + N' 12' + ' #subQueryTxt' + ' #postSubQuery'
select #query = #query + N'
from FinDocPayToPayback pay_and_back
left join FinDocument pay on pay.id = pay_and_back.PayID
left join FinDocument back on back.id = pay_and_back.PaybackID
group by DATEPART(ISO_WEEK, pay.dateCreate) order by 1';
select #query
EXECUTE sp_executesql #query
,N'#preSubQuery nvarchar(200)', #preSubQuery
,N'#subQueryTxt nvarchar(500)', #subQueryTxt
,N'#postSubQuery nvarchar(100)', #postSubQuery;
But i get error Incorrect syntax. First, I need help with this query. Second,
can anyone give more information about how to construct complex dynamic query?

Answer 1

This is your issue. Somewhere in between .... is there, which cause an issue.
Every time you can use print #query, whenever you stuck or get error.
declare #query nvarchar(MAX), #preSubQuery nvarchar(200), #subQueryTxt nvarchar(500), #postSubQuery nvarchar(100);
set #postSubQuery = N' ELSE 0 END))'
set #preSubQuery = N' ,SUM(( CASE DATEDIFF(WEEK, pay.dateCreate, back.dateCreate) WHEN ';
set #subQueryTxt = N' THEN
CASE
WHEN ...
THEN 0
WHEN ...
THEN ...
ELSE
CASE
WHEN ...
THEN ...
WHEN ...
THEN ...
ELSE 0
END
END ';
select #query = N'select DATEPART(ISO_WEEK, pay.dateCreate) backWeek ,SUM(pay_and_back.PayActualPrincipalAmt) AS TotalAmount' +
+ N' #preSubQuery' + N' 0' + ' #subQueryTxt' + ' #postSubQuery'
+ N' #preSubQuery' + N' 1' + ' #subQueryTxt' + ' #postSubQuery'
+ N' #preSubQuery' + N' 2' + ' #subQueryTxt' + ' #postSubQuery'
+ N' #preSubQuery' + N' 12' + ' #subQueryTxt' + ' #postSubQuery'
select #query = #query + N'
from FinDocPayToPayback pay_and_back
left join FinDocument pay on pay.id = pay_and_back.PayID
left join FinDocument back on back.id = pay_and_back.PaybackID
group by DATEPART(ISO_WEEK, pay.dateCreate) order by 1';
select #query
This is actual output of your above query at execution time
SELECT Datepart(iso_week, pay.datecreate) backweek ,
Sum(pay_and_back.payactualprincipalamt) AS totalamount #preSubQuery 0 #subQueryTxt #postSubQuery #preSubQuery 1 #subQueryTxt #postSubQuery #preSubQuery 2 #subQueryTxt #postSubQuery #preSubQuery 12 #subQueryTxt #postSubQuery
FROM findocpaytopayback pay_and_back
LEFT JOIN findocument pay
ON pay.id = pay_and_back.payid
LEFT JOIN findocument back
ON back.id = pay_and_back.paybackid
GROUP BY datepart(iso_week, pay.datecreate)
ORDER BY 1
For complex dynamic query, this is example to understand.
Example1
--declare table1 table ( id int, value varchar(10) )
--drop table Table1
begin tran
create table table1 ( id int, value varchar(10) )
insert into table1 values( 1,'001')
insert into table1 values(2, '002')
insert into table1 values( 3,'003')
insert into table1 values( 4,'004')
create table table2 ( id int, value varchar(10) )
insert into table2 values( 1,'t2value1')
insert into table2 values(2, 't2value2')
insert into table2 values( 3,'t2value3')
insert into table2 values( 4,'t2value4')
-----1st example
declare #sql nvarchar(max) , #temp varchar(50) = '1,2,3'
select * from table1
set #sql = 'select * from table1 where id in ( ' + #temp + ')'
declare #join_table varchar(max)= 'table2', #whereCondition varchar(max) = ' where ' , #orderby varchar(max) = ' t1.id'
select #sql
exec sp_executesql #sql
-----2nd example
set #sql = 'select * from table1 t1 inner join ' + #join_table + ' t2 on t1.id = t2.id '
--if #parameter != null you can give above this condition for
set #whereCondition = #whereCondition + ' t1.id in ( ' + #temp + ')'
--if #orderby != null order by condition
set #orderby = ' order by '+ #orderby
set #sql = #sql + #whereCondition + #orderby
select #sql --you can check that what is wrong by
exec sp_executesql #sql
rollback
**Example2 : Passing parameter into dynamic query **
--begin tran
--create table table1 ( id int, value varchar(10) )
--insert into table1 values( 1,'001')
--insert into table1 values(2, '002')
--insert into table1 values( 3,'003')
--insert into table1 values( 4,'004')
declare #sql nvarchar(max) , #temp nvarchar(50) = '1,2,3', #tempIntSingleValue nvarchar(50) = '2'
select * from table1
set #sql = 'select * from table1 where id in ( ' + #temp + ')'
print #sql
exec sp_executesql #sql
set #sql = 'select * from table1 where id in ( #tempInner)'
print #sql
exec sp_executesql #sql , N'#tempInner int', #tempInner = #tempIntSingleValue
--rollback