How to execute a SQL String that references a table variable? - sql

Question

I have a table variable in SQL Server 2008
DECLARE #specsAndModel TABLE
(
specName VARCHAR(50)
,specVal VARCHAR(50)
)
INSERT INTO #specsAndModel
VALUES('[modelNumber]', 'F00-B4R')
Then, I later build a string called #query, which I ultimately try to pass into EXECUTE, as in the following example:
DECLARE #query NVARCHAR(MAX);
SET #query = 'SELECT specName, specVal FROM #specsAndModel'
EXECUTE(#query)
However, SQL Server gives me the error message: Must declare the table variable "#specsAndModel".
After searching around, I think this might be related to the execution context, but I haven't been able to resolve the problem.
Is it even possible for me to use a table variable in a call to the execute function?

Answer 1

The table you are creating is a table variable which is not available outside of its initial scope. There are a few ways to fix this:
Create a Global Temp Table (Disclaimer: this can cause problems if more that one user attempts to run this at the same time.):
create table ##specsAndModel
(
specName VARCHAR(50)
,specVal VARCHAR(50)
)
INSERT INTO ##specsAndModel
VALUES('[modelNumber]', 'F00-B4R')
DECLARE #query NVARCHAR(MAX);
SET #query = 'SELECT specName, specVal FROM ##specsAndModel'
EXECUTE(#query)
Create a Local Temp Table instead of global:
create table #specsAndModel
(
specName VARCHAR(50)
,specVal VARCHAR(50)
)
INSERT INTO #specsAndModel
VALUES('[modelNumber]', 'F00-B4R')
DECLARE #query NVARCHAR(MAX);
SET #query = 'SELECT specName, specVal FROM #specsAndModel'
EXECUTE(#query)
Execute the create table inside of your dynamic SQL (ugly):
DECLARE #query NVARCHAR(MAX);
SET #query = 'DECLARE #specsAndModel TABLE
(
specName VARCHAR(50)
,specVal VARCHAR(50)
)
INSERT INTO #specsAndModel
VALUES(''[modelNumber]'', ''F00-B4R'')
SELECT specName, specVal FROM #specsAndModel'
exec(#query)
Instead of using a temp table, create an actual table and then drop it when done (Disclaimer: this can cause problems if more that one user attempts to run this at the same time.):
create TABLE specsAndModel
(
specName VARCHAR(50)
,specVal VARCHAR(50)
)
INSERT INTO specsAndModel
VALUES('[modelNumber]', 'F00-B4R')
DECLARE #query NVARCHAR(MAX);
SET #query = 'SELECT specName, specVal FROM specsAndModel'
EXECUTE(#query)
drop table specsAndModel
Here is an link to a discussion about temp tables and table variables:
Should I use a #temp table or a #table variable?
Edit: You can pass in a table variable using sp_executesql:
create type specsAndModel as table (
specName VARCHAR(50)
,specVal VARCHAR(50)
)
go
declare #t specsAndModel
insert #t VALUES('[modelNumber]', 'F00-B4R')
exec sp_executesql N'select specName, specVal from #var', N'#var specsAndModel readonly', #t
Using either the global ##temp tables and a permanent table run risks in that if more than one users attempts to run the process, there could be conflicts.
You are safer using either a local #temp table or passing the table variable using sp_executesql.

Answer 2

You also have to create your table variable inside the in the string.
DECLARE #query NVARCHAR(MAX);
SET #query = 'DECLARE #specsAndModel TABLE ( specName VARCHAR(50) ,specVal VARCHAR(50))'
SET #Query = #Query + ' INSERT INTO #specsAndModel VALUES(''modelNumber'',''abcd''); SELECT specName, specVal FROM #specsAndModel'
EXEC (#query)