How to store values from a dynamic sql into a variable? - sql

I am trying to store next value for the sequence into a variable and the statement is called in a dynamic sql as below.
DECLARE #Sequence VARCHAR(100) = 'IMEIIDLookUP'
DECLARE #NextVal INT
DECLARE #SQL NVARCHAR(4000)
SELECT #SQL = 'SELECT (NEXT VALUE FOR [dbo].' + QUOTENAME(#Sequence) + ')'
SELECT #NextVal = EXEC (#SQL)
SELECT #NextVal
The above query fails with error
Incorrect syntax near the keyword 'EXEC'.
What would be the correct syntax here? Having said that, I cannot avoid using dynamic sql.

Use sp_executesql:
DECLARE #Sequence VARCHAR(100) = 'IMEIIDLookUP';
DECLARE #NextVal INT;
DECLARE #SQL NVARCHAR(4000);
SELECT #SQL = 'SELECT #NextVal = (NEXT VALUE FOR [dbo].' + QUOTENAME(#Sequence) + ')';
exec sp_executesql #SQL, N'#NextVal int output', #NextVal = #NextVal output;
SELECT #NextVal;

Related

Performing Calculation on dynamic sql

Why does the following error out? It seems the SQL server doesn't recognize - operator on dynamic sql
DECLARE #value INT;
SELECT #value = 10;
EXEC ('SELECT ' + #value -1 );
Nope. You should set up the statement before running it. I would recommend:
DECLARE #value INT;
DECLARE #sql NVARCHAR(MAX);
SET #SQL = 'SELECT #value - 1';
SELECT #value = 10;
EXEC sp_executesql #sql, N'#value int', #value = #value ;
This uses parameters and so is a much more sensible way to run the query.
This works:
DECLARE #value INT;
SELECT #value = 10;
EXEC ('SELECT ' + #value +' -1 ');

T sql - How to store results from a dynamic query using EXEC or EXECUTE sp_executesql

I am trying to write a dynamic query. Let's say i have a table like below, which represents the hierarchy level of a sales agent:
AgentNumber Level1Agent Level2Agent Level3Agent Level4Agent Level5Agent
1122334455 1122334499 1122334488 1122334477 1122334466 1122334455
I want to be able to dynamically select a level based on a specified agent. My EXECUTE statement seems to work correctly, but how do I get the result stored in a variable I can use later? Every answer I have found seems to only get me a success return variable, not the actual query result.
Below is my code:
DECLARE #level INT = 1;
DECLARE #agent CHAR(10) = 1122334455;
DECLARE #colname NVARCHAR(11) = CONCAT('Level',#level,'Agent');
DECLARE #whereclause NVARCHAR(35) = CONCAT('WHERE AgentNumber = ',#agent);
DECLARE #qry NVARCHAR(300) = 'SELECT ' + #colname + ' FROM dbo.TABLE ' + #whereclause;
DECLARE #up NVARCHAR(10);
EXECUTE sp_executesql #qry, #up OUT
SELECT #up
The output of #up is NULL. If I change the last two lines to:
EXECUTE #up = sp_executesql #qry
SELECT #up
Now the output of #up is 0.
I want the output of 1122334499 and I need it stored in a variable that can later be used and inserted into a table.
Here is a fully functional example of how you can do this. Notice this is using a parameterized where clause and quotename around the column name in the dynamic sql to prevent sql injection.
if OBJECT_ID('tempdb..#Agents') is not null
drop table #Agents
create table #Agents
(
AgentNumber char(10)
, Level1Agent char(10)
, Level2Agent char(10)
, Level3Agent char(10)
, Level4Agent char(10)
, Level5Agent char(10)
)
insert #Agents
select '1122334455', '1122334499', '1122334488', '1122334477', '1122334466', '1122334455'
DECLARE #level INT = 3;
DECLARE #agent CHAR(10) = 1122334455;
DECLARE #colname NVARCHAR(11) = CONCAT('Level',#level,'Agent');
declare #agentout char(10)
DECLARE #qry NVARCHAR(300) = 'SELECT #agent_out = ' + quotename(#colname) + ' FROM #Agents WHERE AgentNumber = #agentin';
EXECUTE sp_executesql #qry, N'#agentin char(10), #agent_out char(10) output', #agentin = #agent, #agent_out = #agentout output
select #agentout
You can try this :
DECLARE #level INT = 1;
DECLARE #agent CHAR(10) = 1122334455;
DECLARE #colname NVARCHAR(11) = CONCAT('Level',#level,'Agent');
DECLARE #whereclause NVARCHAR(35) = CONCAT('WHERE AgentNumber = ',#agent);
DECLARE #qry NVARCHAR(300) = 'SELECT #agentout=' + #colname + ' FROM dbo.TABLE ' + #whereclause;
DECLARE #up NVARCHAR(10);
EXECUTE sp_executesql #qry, N'#agentout NVARCHAR(10) OUTPUT', #agentout=#up OUTPUT
SELECT #up
Create a variable table and makes your query insert the results you want there. Something like this:
declare #results table(field1 varchar(max), field2 varchar(max));
declare #sqlStatement varchar(max);
set #sqlStatement = 'insert into #results(field1, field2) select field1, field2 from table';
EXECUTE #sqlStatement;
select * from #results; --It will print the results from your sql statement!

Dynamic SQL output of a query to a variable

I would like to output the result of the dynamic SQL into a variable called #Count but not sure what the syntax or even the code should like to accomplish this.
The code looks as follows:
declare #tab nvarchar(255) = 'Person.person'
declare #Count int
declare #SQL nvarchar(max) = 'select count(*) from '+ #tab
exec(#SQl)
select #Count
thank you
Here's another way to do it that also safely addresses the SQL Injection isuues:
/* Counts the number of rows from any non-system Table, *SAFELY* */
-- The table name passed
DECLARE #PassedTableName as NVarchar(255) = 'Person.Person';
-- Make sure this isn't a SQL Injection attempt
DECLARE #ActualTableName AS NVarchar(255)
SELECT #ActualTableName = TABLE_SCHEMA + '.' + TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_NAME = PARSENAME(#PassedTableName,1)
AND TABLE_SCHEMA = PARSENAME(#PassedTableName,2)
-- make a temp table to hold the results
CREATE TABLE #tmp( cnt INT );
-- create the dynamic SQL
DECLARE #sql AS NVARCHAR(MAX)
SELECT #sql = 'SELECT COUNT(*) FROM ' + #ActualTableName + ';'
-- execute it and store the output into the temp table
INSERT INTO #tmp( cnt )
EXEC(#SQL);
-- Now, finally, we can get it into a local variable
DECLARE #result AS INT;
SELECT #result = cnt FROM #tmp;
You can utilize sp_executesql to execute your count() query, and output it #Count.
Try this:
-- Set the table to count from
declare #tab nvarchar(255) = 'Person.person'
-- Assign the SQL query
declare #SQL nvarchar(255) = N'SELECT count(*) FROM ' + #tab
-- Pepare for sp_executesql
declare #Count int
declare #Params nvarchar(100) = N'#Count int output'
-- Set the count to #Count
exec sp_executesql #SQL, #Params, #Count=#Count output
-- Output #Count
select #Count
One last thing: Person.person looks like you might be trying to reference a person column from a Person table. But the above query is a literal representation of what it looks like you're trying to achieve in your question.
The below question is pretty much identical to what you are asking here.
sp_executeSql with output parameter
DECLARE #retval int
DECLARE #sSQL nvarchar(500);
DECLARE #ParmDefinition nvarchar(500);
DECLARE #tablename nvarchar(50)
SELECT #tablename = N'products'
SELECT #sSQL = N'SELECT #retvalOUT = MAX(ID) FROM ' + #tablename;
SET #ParmDefinition = N'#retvalOUT int OUTPUT';
EXEC sp_executesql #sSQL, #ParmDefinition, #retvalOUT=#retval OUTPUT;
SELECT #retval;

How to return the rowcount of a dynamic sql query in SP?

I would like to return the rowcount of a dynamic sql query using linq similar to mentioned here:
http://weblogs.asp.net/scottgu/archive/2007/08/16/linq-to-sql-part-6-retrieving-data-using-stored-procedures.aspx
I'm using dynamic sql to create the where clause and to implement paging on the result set, The rowcount I want to return is the total number of records that meet the where condition.
My SQL that is causing me problems:
-- get row count
SET #SQL = '#TotalRowCount = SELECT COUNT(*) as TotalRowCount'
SET #SQL = #SQL + #WHERE
IF (LEN(#SUBWHERE) > 0)
BEGIN
SET #SQL = #SQL + #SUBWHERE
END
SET #SQL = #SQL + ')) '
exec sp_executesql #SQL
END
(I need this to be the output param #TotalRowCount in the param list here):
ALTER PROCEDURE [dbo].[_tournament_GetTournamentsByConveners]
(
#LastName varchar(100) = null ,
#Username varchar(256) = null ,
#Email varchar(100) = null ,
#IsWildcard bit = null,
#PageIndex int ,
#PageSize int,
#TotalRowCount int output
)
AS
This is by design.
The scope of the #TotalRowCount in the dynamic SQL is different to the scope of #TotalRowCount declared in the stored procedure. That is, the dynamic SQL has it's own scope.
If you insist on using dynamic SQL, do this to add the total rows to the record set that is returned
SELECT col1, col2,
COUNT(*) OVER () AS TotalRows
FROM ...
Otherwise we only have partial code to offer any suggestions for improvement. You appear to have LINQ to call stored procs with execute dynamic SQL. This is too convoluted.
You can declare output parameters with sp_executesql. So to get your result alter the code as shown below.
Always be careful when concatenating SQL code like this as it is extremely vulnerable to SQL injection.
DECLARE #SQL nvarchar(4000)
SET #SQL = N'SELECT #TotalRowCount = COUNT(*) as TotalRowCount'
SET #SQL = #SQL + #WHERE
IF (LEN(#SUBWHERE) > 0)
BEGIN
SET #SQL = #SQL + #SUBWHERE
END
SET #SQL = #SQL + N')) '
exec sp_executesql #SQL, N'#TotalRowCount int output', #TotalRowCount output
you can also express this more compact as:
DECLARE #SQL nvarchar(4000)
SET #SQL = N'SELECT #TotalRowCount = COUNT(*) as TotalRowCount' + #WHERE + ISNULL(#SUBWHERE, N'') + N'))'
exec sp_executesql #SQL, N'#TotalRowCount int output', #TotalRowCount output

Dynamic sql statement to update a variable

my sql statement is something like this below
DECLARE #OLD_NAV_VALUE AS INT
DECLARE #FINAL AS INT
SELECT #OLD_NAV_VALUE = [col1] from TBL_BA where DATE = #id_Date
SET #FINAL = #OLD_NAV_VALUE * 50
But the problem i am haveing here is that the column name in the select statement which is given as [col1] is a dynamic value. So i am trying something like this below.
DECLARE #OLD_NAV_VALUE AS INT
DECLARE #FINAL AS INT
EXEC('SELECT #OLD_NAV_VALUE = [' + #DYNAMIC_COL_NAME + '] from TBL_BA where DATE = ' + #id_Date)
SET #FINAL = #OLD_NAV_VALUE * 50
this gives an error that #OLD_NAV_VALUE has to be declared. So i tried declaring #OLD_NAV_VALUE inside the EXEC statement. But if i do this i am not able to use the same outside the EXEC statement.
Please let me know how to do this.
You can also use the sp_executesql statement with an output parameter:
declare #field nvarchar(50);
set #field = N'FieldToSelect';
declare #sql nvarchar(3000);
declare #parmDefinition nvarchar(500);
SET #parmDefinition = N'#returnValueOUT nvarchar(50) OUTPUT';
set #sql = N'SELECT #ReturnValueOUT = ' + #Field + ' FROM [TableName] WHERE [SomeCondition]'
declare #returnValue nvarchar(50);
EXECUTE sp_executesql #sql, #parmDefinition, #returnValueOut = #returnValue OUTPUT;
SELECT #returnValue
First, I'd suggest that you do a Google on "Erland dynamic SQL" and read his white paper on the subject.
Your design is probably not the best if it requires that you use a dynamic column name like this.
The reason that you can't do what you're trying to do is that everything in the EXEC is entirely in its own scope. If you absolutely have to do it this way though then you could use a table (either a normal table, or a global temporary table) to store the value for use outside of the EXEC.
We've used sp_executesql. Here's another example of a parameterized record count:
DECLARE #sql AS nvarchar(MAX)
SET #sql = N'SELECT #RecordCount = COUNT(*) FROM [{#SchemaName}].[{#TableName}]'
SET #sql = REPLACE(#sql, '{#SchemaName}', #SchemaName)
SET #sql = REPLACE(#sql, '{#TableName}', #TableName)
DECLARE #RecordCount AS int
EXEC sp_executesql
#query = #sql,
#params = N'#RecordCount INT OUTPUT',
#RecordCount = #RecordCount OUTPUT
This worked for me.
I declared a temp table and used it to receive the values from the select statement.
Something like below.
declare #i int
declare #v int
create table #t (val int)
insert into #t
exec ('declare #i int set #i = 0 select #i+1')
select * from #t