How to grab the value of the output parameter in execute sp_executesql? - sql

Question

Please forgive newbie's ignorance!
How do I grab the value of the output parameter in execute sp_executesql?
I can see the output but cannot get to it:
DECLARE #LastActivity nvarchar(100)
DECLARE #LastActivityDate datetime
DECLARE #sql nvarchar(MAX)
DECLARE #RowsToProcess int
DECLARE #CurrentRow int
DECLARE #SelectCol1 nvarchar(100)
DECLARE #SelectCol2 nvarchar(100)
DECLARE #SelectCol3 nvarchar(100)
DECLARE #LastDate TABLE (RowID int not null primary key identity(1,1), col4 nvarchar(MAX), col5 sql_variant)
DECLARE #table1 TABLE (RowID int not null primary key identity(1,1), col1 nvarchar(100),col2 nvarchar(100),col3 nvarchar(100))
INSERT into #table1 (col1,col2,col3)(SELECT t.name AS col1, c.name AS col2, m.Field1 as col3
FROM sys.columns c INNER JOIN
sys.tables t ON c.object_id = t.object_id INNER JOIN
sys.schemas s ON t.schema_id = s.schema_id INNER JOIN
dbo.MERGE_TABLES m ON m.Table_Name=t.name
WHERE c.name LIKE '%[_]DATE%' and m.[Enabled]='Y')
SET #RowsToProcess=##ROWCOUNT
SET #CurrentRow=0
WHILE #CurrentRow<#RowsToProcess
BEGIN
SET #CurrentRow=#CurrentRow+1
SELECT #SelectCol1=col1,#SelectCol2=col2,#SelectCol3=col3 FROM #table1 WHERE RowID=#CurrentRow
SET #sql='SELECT ' + '[dbo].[ConvertToDatetime](MAX(' + #SelectCol2 + '))' + ' FROM ' + #SelectCol1 + ' Where ' + #SelectCol3 + ' = ' + '''0722607QZ'''
Declare #params as nvarchar(MAX)
Set #params = '#date sql_variant output'
Declare #date as sql_variant;
execute sp_executesql
#sql
,#params
,#date output
Select #date
INSERT into #LastDate VALUES (#sql, #date)
end
select col4,col5 from #LastDate
select col4,col5 from #LastDate gives me the SQL script in clo4 but col5 is empty! I need to store the #date as I still need to get the Max(#date)
Thanx a million.
SET #sql='set #date =('SELECT ' + '[dbo].[ConvertToDatetime](MAX(' +
#SelectCol2 + '))' + ' FROM ' + #SelectCol1 + ' Where ' + #SelectCol3
+ ' = ' + '''0722607QZ''' ) '
the above sql gives me error: Incorrect syntax near '.'
SET #sql='set #date =(SELECT [dbo].[ConvertToDatetime](MAX( + #SelectCol2 + ))
FROM #SelectCol1 Where #SelectCol3 ''=0722607QZ'' ) '
The above sql gives the error: Must declare the scalar variable "#SelectCol2"
SET #sql='SELECT ' + #date + '=convert(nvarchar(100), [dbo].[ConvertToDatetime](MAX(' + #SelectCol2 + ')))' + ' FROM ' + #SelectCol1 + ' Where ' + #SelectCol3 + ' = ' + '''0722607QZ'''
the above produces the error : Implicit conversion from data type sql_variant to nvarchar is not
allowed. Use the CONVERT function to run this query.
SET #sql='SELECT ' + #date + '=convert(nvarchar(MAX),(MAX(' + #SelectCol2 + '))' + ' FROM ' + #SelectCol1 + ' Where ' + #SelectCol3 + ' = ' + '''0722607QZ'''
the above produces no error but all output is NULL, no values.

Answer 1

Your syntax looks ok but you never assign to the output variable #date hence no value.
Instead of;
SET #sql='SELECT ...'
You need;
SET #sql='set #date = (SELECT ...'
Can't you use a better type than sql_variant?