Issue with SQL variable

Question

Please could someone help me understand, why when I run the below SQL code it returns an "s". But when I run the SQL portion on its own it returns the correct value "DaisyRates_May2014"

Full code:

DECLARE @tablevalue varchar

SET @tablevalue = 'select distinct [BillingReferenceData].[dbo].[Customers].[Tariff]
from [daisybilling].[dbo].[APRW14_FFA68878_Calls]
inner join [BillingReferenceData].[dbo].[Customers] on [DaisyBilling].[dbo].[APRW14_FFA68878_Calls].[Customer Lookup] = [BillingReferenceData].[dbo].[Customers].[Customer ID]
where [DaisyBilling].[dbo].[APRW14_FFA68878_Calls].[Customer Lookup] = [BillingReferenceData].[dbo].[Customers].[Customer ID]'

Select @tablevalue

SQL on its own:

'select distinct [BillingReferenceData].[dbo].[Customers].[Tariff]
from [daisybilling].[dbo].[APRW14_FFA68878_Calls]
inner join [BillingReferenceData].[dbo].[Customers] on [DaisyBilling].[dbo].[APRW14_FFA68878_Calls].[Customer Lookup] = [BillingReferenceData].[dbo].[Customers].[Customer ID]
where [DaisyBilling].[dbo].[APRW14_FFA68878_Calls].[Customer Lookup] = [BillingReferenceData].[dbo].[Customers].[Customer ID]

Thanks

Answer 1

You are returning an s because you are returning the first character of the sql string since you haven't defined a length of your variable. Try using varchar(max) instead of varchar .

However, that will just return your sql statement, not run it. I think you want to actually run your sql statement, in which case, you can use exec or sp_executesql .

DECLARE @tablevalue varchar(max) 

SET @tablevalue = 'select distinct [BillingReferenceData].[dbo].[Customers].[Tariff]
from [daisybilling].[dbo].[APRW14_FFA68878_Calls]
inner join [BillingReferenceData].[dbo].[Customers] on [DaisyBilling].[dbo].[APRW14_FFA68878_Calls].[Customer Lookup] = [BillingReferenceData].[dbo].[Customers].[Customer ID]
where [DaisyBilling].[dbo].[APRW14_FFA68878_Calls].[Customer Lookup] = [BillingReferenceData].[dbo].[Customers].[Customer ID]'

exec(@tablevalue)

Answer 2

You are specifying the the type of @tablevalue is a varchar of length one. Try

DECLARE @tablevalue VARCHAR(MAX)

From http://msdn.microsoft.com/en-us/library/ms176089.aspx

When n is not specified in a data definition or variable declaration statement, the default length is 1

To execute to SQL:

EXEC SP_EXECUTESQL(@tablevalue )

or

EXEC(@tablevalue)

Take a look at http://www.sommarskog.se/dynamic_sql.html to learn about the differences between EXEC and AP_EXECUTESQL.