Appending variables inside dynamic sql in sql server - sql

Question

I'm having trouble building a dynamic sql string to run an openquery. When I print the query string it evaluates the variable name as string instead of the actual value. Here's what I have:
Declare #tsql varchar(1000)
Declare #book_review_start as date
Declare #book_review_end as date
set #book_review_start = convert(varchar(10),DATEADD(month, DATEDIFF(month, 0, GETDATE())-2, 0), 120)
set #book_review_end = convert(varchar(10), DATEADD(mm, DATEDIFF(mm, 0, GETDATE()), -2), 120)
Set #tsql = 'select * from openquery(authorsdb, ''select distinct ssn as bsn
from authors.dbo.nytimes where review_date between '' + #book_review_start + 'and' + '#book_review_end' + 'and review = 'annual'
and city_name = ''
and review_hrs = 0
and review_days = 0')'
That throws all kinds of conversion errors and such.

Answer 1

1) You need 1 or more extra ' single quote characters in 1 or more places in your statement.
2) The DATE values need to converted to string / VARCHAR since you are concatenating string to generate the dynamic SQL statement.
The following works.
DECLARE #tsql VARCHAR(1000)
DECLARE #book_review_start AS DATE
DECLARE #book_review_end AS DATE
SET #book_review_start = DATEADD(month, DATEDIFF(month, 0, GETDATE())-2, 0)
set #book_review_end = DATEADD(mm, DATEDIFF(mm, 0, GETDATE()), -2)
Set #tsql = 'SELECT * FROM OPENQUERY(authorsdb, ''SELECT DISTINCT ssn AS bsn FROM authors.dbo.nytimes WHERE review_date BETWEEN'''
+ CONVERT(varchar(20),#book_review_start) + ''' AND ''' + CONVERT(varchar(20),#book_review_end ) + ''''
+ ' AND review = ''annual'' AND city_name = '''' AND review_hrs = 0 AND review_days = 0 )'
PRINT #tsql
The OUTPUT of the PRINT Statement is as follows.
SELECT * FROM OPENQUERY(authorsdb, 'SELECT DISTINCT ssn AS bsn FROM
authors.dbo.nytimes WHERE review_date BETWEEN'2016-05-01' AND
'2016-06-30' AND review = 'annual' AND city_name = '' AND review_hrs =
0 AND review_days = 0 )

Answer 2

If the intent is to eventually do this:
exec sp_executesql #tsql
then, as a minimum you must:
1 Make #tsql an nvarchar variable as opposed to varchar.
2 As suggested by Serg, all single quotes in the sql part become 4 single quotes. For example, this:
and city_name = ''
becomes this:
and city_name = ''''''''
3 You need spaces around words. For example this:
where review_date between '' + #book_review_start + 'and'
must be this:
where review_date between ' + #book_review_start + ' and '
This should get you started. Read the other answers as well.

Answer 3

Your query issues are
- #book_review_start / end declared DATE, should be VARCHAR to take part in concatenation
- to have a quote in a quoted string you need double quote, to have quoted string in a quoted string you need 4 quotes
Try
Declare #tsql varchar(1000)
Declare #book_review_start varchar(10)
Declare #book_review_end varchar(10)
set #book_review_start = convert(varchar(10),DATEADD(month, DATEDIFF(month, 0, GETDATE())-2, 0), 120)
set #book_review_end = convert(varchar(10), DATEADD(mm, DATEDIFF(mm, 0, GETDATE()), -2), 120)
Set #tsql = 'select * from openquery(authorsdb, ''select distinct ssn as bsn
from authors.dbo.nytimes where review_date between ''''' + #book_review_start + ''''' and ''''' + #book_review_end + ''''' and review = ''''annual''''
and city_name = ''''''''
and review_hrs = 0
and review_days = 0'')' ;
select #tsql;