I’m trying to create a very simple stored procedure which would do the following:
EXEC sp_help N’some.table’
SELECT TOP 1000 * FROM some.table
So far I have the following
CREATE PROCEDURE info_qry(#tbl)
BEGIN
DECLARE #tbl varchar(100)
EXEC sp_help N’#tbl’
SELECT TOP 1000 * FROM #tbl
END
I can’t figure it out how to pass the #tbl variable after the N’’ part so it is taken as a variable and not as a constant. How to do that?
Any help is appreciated.
Apologies about formatting I’m on mobile.
You can use dynamic SQL:
declare #sql nvarchar(max);
set #sql = 'sp_help ''' + #tbl + '''';
exec(#sql);
Related
Alright so say I have code that looks like this.
CREATE Table database_info
(
DBName NVARCHAR (MAX)
);
INSERT INTO database_info (DBName)
VALUES ('db1')
SELECT * FROM database_info
DECLARE #temp nvarchar(MAX)
SET #temp = (SELECT DBName FROM database_info where database_info.DBName = 'db1')
--How I want it to work SELECT * FROM #temp
Is there any kind of operation I could do on this temporary variable to have the string act as a regular SQL command?
Thanks
You may execute a dynamic sql using EXEC. Now, declaring the #sql variable would be quite too much in this case, but it is useful when you are not sure of the length of the statement you will pass to it.
DECLARE #sql AS VARCHAR(MAX)
SET #sql = 'SELECT * FROM ' + #temp
EXEC(#sql)
This question already has answers here:
SQL: Select dynamic column name based on variable
(3 answers)
Closed 8 years ago.
I have a web page with a link to a stored procedure and I want to pass a variable to the stored procedures select statement. The code so far is -
ALTER procedure [dbo].[RTO]
#Weeknumber int,
#asset nvarchar(50)
AS
Begin
SELECT #asset
FROM RTO_weeklyanalysis
Where weekNumber = #weeknumber
END
basically the #asset will be the name of the column but this will change depending on what the user selects on the page.
You will need to use Dynamic sql for this. Also use QuoteName() function when concatenating object names to your sql query. and use system stored procedure sp_executesql to execute the dynamic query the most safe and secure way of executing dynamic sql. Something as follows :
ALTER procedure [dbo].[RTO]
#Weeknumber int,
#asset sysname
AS
Begin
SET NOCOUNT ON;
DECLARE #Sql NVARCHAR(MAX);
SET #Sql = N' SELECT '+ QUOTENAME(#asset) + '
FROM RTO_weeklyanalysis
Where weekNumber = #weeknumber'
EXECUTE sp_executesql #Sql
,N'#Weeknumber int'
,#Weeknumber
END
You cannot use a column name dynamicly in this way. The simplest way to achiewe what you want will be to exec whole query from temporary variable, i mean:
declare #query
set #query = 'SELECT ' + #asset ' FROM RTO_weeklyanalysis Where weekNumber = #weeknumber'
exec sp_executesql #query
I want to create a SQL tabled-value function that will receive a query as n parameter through my API. In my function I want execute that query. The query will be a SELECT statement.
This is what I have done so far and what to achieve but it is not the correct way to do so.
CREATE FUNCTION CUSTOM_EXPORT_RESULTS (
#query varchar(max),
#guid uniqueidentifier,
#tableName varchar(200))
RETURNS TABLE
AS
RETURN
(
-- Execute query into a table
SELECT *
INTO #tableName
FROM (
EXEC(#query)
)
)
GO
Please suggest the correct way!
Try this one -
CREATE PROCEDURE dbo.sp_CUSTOM_EXPORT_RESULTS
#query NVARCHAR(MAX) = 'SELECT * FROM dbo.test'
, #guid UNIQUEIDENTIFIER
, #tableName VARCHAR(200) = 'test2'
AS BEGIN
SELECT #query =
REPLACE(#query,
'FROM',
'INTO [' + #tableName + '] FROM')
DECLARE #SQL NVARCHAR(MAX)
SELECT #SQL = '
IF OBJECT_ID (N''' + #tableName + ''') IS NOT NULL
DROP TABLE [' + #tableName + ']
' + #query
PRINT #SQL
EXEC sys.sp_executesql #SQL
RETURN 0
END
GO
Output -
IF OBJECT_ID (N'test2') IS NOT NULL
DROP TABLE [test2]
SELECT * INTO [test2] FROM dbo.test
What I see in your question is encapsulation of:
taking a dynamic SQL expression
executing it to fill a parametrized table
Why do you want to have such an encapsulation?
First, this can have a negative impact on your database performance. Please read this on EXEC() and sp_executesql() . I hope your SP won't be called from multiple parts of your application, because this WILL get you into trouble, at least performance-wise.
Another thing is - how and where are you constructing your SQL? Obviously you do it somewhere else and it seems its manually created. If we're talking about a contemporary application, there are lot of OR/M solutions for this and manual construction of TSQL in runtime should be always avoided if possible. Not to mention EXEC is not guarding you against any form of SQL injection attacks. However, if all of this is a part of some database administration TSQL bundle, forget his paragraph.
At the end, if you want to simply load a new table from some existing table (or part of it) as a part of some administration task in TSQL, consider issuing a SELECT ... INTO ... This will create a new target table structure for you (omitting indexes and constraints) and copy the data. SELECT INTO will outperform INSERT INTO SELECT because SELECT INTO gets minimally logged.
I hope this will get you (and others) at least a bit on the right track.
You can use stored procedure as well, here is the code that you can try.
CREATE FUNCTION CUSTOM_EXPORT_RESULTS
(
#query varchar(max),
#guid uniqueidentifier,
#tableName varchar(200)
)
RETURNS TABLE
AS
RETURN
(
declare #strQuery nvarchar(max)
-- Execute query into a table
SET #strQuery = REPLACE(#query,'FROM', 'INTO '+#tableName+' FROM')
exec sp_executesql #strQuery
)
GO
I need to get the table name to query from a table.
var tableName = "select tableName from tableList where type='A';"
Then subsequently use that table name in another query.
"select * from" + tableName
Transact SQL/stored procedures are new to me in general so any help would be appreciated. I didn't design the database and unfortunately can't really change it to be a better design as much as I would love to!
My question is - is this possible from one stored procedure and if so can anyone mock up how I'd do it.
Or if there are any better ways anyone can think of (bar redesigning the database!)
Thanks
Maybe via dynamic SQL
DECLARE #String AS VARCHAR(8000)
DECLARE #TableName AS VARCHAR(50)
DECLARE #Results AS VARCHAR(8000)
SET #TableName = (select top 1 tableName from tableList where type='A')
SET #String = 'Select * from ' + #TableName
SET #Results = #String + #TableName
EXEC #Results
You can either use execas #kevchadders suggested or you can use sp_executesql, read The Curse and Blessings of Dynamic SQL for an excellent explantion on dynamic SQL.
You should use dynamic SQL to achieve that.
Basically, you execute your query using sp_executesql or exec, and store the result to a, kinda, staging table to be processed further:
declare #sql = varchar(8000);
select #sql = 'insert into resulttbl select * from ' + #tableName;
exec sp_executesql(#sql);
-- further process using resulttbl
Or
insert into resulttbl
exec ('select * from ' + #tableName);
-- further process using resulttbl
Anyway, you should read the following article for a better explanation: The Curse and Blessings of Dynamic SQL
You can directly write
select * from (select tableName from tableList where type='A') X
I have some code like this that I use to do a BULK INSERT of a data file into a table, where the data file and table name are variables:
DECLARE #sql AS NVARCHAR(1000)
SET #sql = 'BULK INSERT ' + #tableName + ' FROM ''' + #filename + ''' WITH (CODEPAGE=''ACP'', FIELDTERMINATOR=''|'')'
EXEC (#sql)
The works fine for standard tables, but now I need to do the same sort of thing to load data into a temporary table (for example, #MyTable). But when I try this, I get the error:
Invalid Object Name: #MyTable
I think the problem is due to the fact that the BULK INSERT statement is constructed on the fly and then executed using EXEC, and that #MyTable is not accessible in the context of the EXEC call.
The reason that I need to construct the BULK INSERT statement like this is that I need to insert the filename into the statement, and this seems to be the only way to do that. So, it seems that I can either have a variable filename, or use a temporary table, but not both.
Is there another way of achieving this - perhaps by using OPENROWSET(BULK...)?
UPDATE:
OK, so what I'm hearing is that BULK INSERT & temporary tables are not going to work for me. Thanks for the suggestions, but moving more of my code into the dynamic SQL part is not practical in my case.
Having tried OPENROWSET(BULK...), it seems that that suffers from the same problem, i.e. it cannot deal with a variable filename, and I'd need to construct the SQL statement dynamically as before (and thus not be able to access the temp table).
So, that leaves me with only one option which is to use a non-temp table and achieve process isolation in a different way (by ensuring that only one process can be using the tables at any one time - I can think of several ways to do that).
It's annoying. It would have been much more convenient to do it the way I originally intended. Just one of those things that should be trivial, but ends up eating a whole day of your time...
You could always construct the #temp table in dynamic SQL. For example, right now I guess you have been trying:
CREATE TABLE #tmp(a INT, b INT, c INT);
DECLARE #sql NVARCHAR(1000);
SET #sql = N'BULK INSERT #tmp ...' + #variables;
EXEC master.sys.sp_executesql #sql;
SELECT * FROM #tmp;
This makes it tougher to maintain (readability) but gets by the scoping issue:
DECLARE #sql NVARCHAR(MAX);
SET #sql = N'CREATE TABLE #tmp(a INT, b INT, c INT);
BULK INSERT #tmp ...' + #variables + ';
SELECT * FROM #tmp;';
EXEC master.sys.sp_executesql #sql;
EDIT 2011-01-12
In light of how my almost 2-year old answer was suddenly deemed incomplete and unacceptable, by someone whose answer was also incomplete, how about:
CREATE TABLE #outer(a INT, b INT, c INT);
DECLARE #sql NVARCHAR(MAX);
SET #sql = N'SET NOCOUNT ON;
CREATE TABLE #inner(a INT, b INT, c INT);
BULK INSERT #inner ...' + #variables + ';
SELECT * FROM #inner;';
INSERT #outer EXEC master.sys.sp_executesql #sql;
It is possible to do everything you want. Aaron's answer was not quite complete.
His approach is correct, up to creating the temporary table in the inner query. Then, you need to insert the results into a table in the outer query.
The following code snippet grabs the first line of a file and inserts it into the table #Lines:
declare #fieldsep char(1) = ',';
declare #recordsep char(1) = char(10);
declare #Lines table (
line varchar(8000)
);
declare #sql varchar(8000) = '
create table #tmp (
line varchar(8000)
);
bulk insert #tmp
from '''+#filename+'''
with (FirstRow = 1, FieldTerminator = '''+#fieldsep+''', RowTerminator = '''+#recordsep+''');
select * from #tmp';
insert into #Lines
exec(#sql);
select * from #lines
Sorry to dig up an old question but in case someone stumbles onto this thread and wants a quicker solution.
Bulk inserting a unknown width file with \n row terminators into a temp table that is created outside of the EXEC statement.
DECLARE #SQL VARCHAR(8000)
IF OBJECT_ID('TempDB..#BulkInsert') IS NOT NULL
BEGIN
DROP TABLE #BulkInsert
END
CREATE TABLE #BulkInsert
(
Line VARCHAR(MAX)
)
SET #SQL = 'BULK INSERT #BulkInser FROM ''##FILEPATH##'' WITH (ROWTERMINATOR = ''\n'')'
EXEC (#SQL)
SELECT * FROM #BulkInsert
Further support that dynamic SQL within an EXEC statement has access to temp tables outside of the EXEC statement. http://sqlfiddle.com/#!3/d41d8/19343
DECLARE #SQL VARCHAR(8000)
IF OBJECT_ID('TempDB..#BulkInsert') IS NOT NULL
BEGIN
DROP TABLE #BulkInsert
END
CREATE TABLE #BulkInsert
(
Line VARCHAR(MAX)
)
INSERT INTO #BulkInsert
(
Line
)
SELECT 1
UNION SELECT 2
UNION SELECT 3
SET #SQL = 'SELECT * FROM #BulkInsert'
EXEC (#SQL)
Further support, written for MSSQL2000 http://technet.microsoft.com/en-us/library/aa175921(v=sql.80).aspx
Example at the bottom of the link
DECLARE #cmd VARCHAR(1000), #ExecError INT
CREATE TABLE #ErrFile (ExecError INT)
SET #cmd = 'EXEC GetTableCount ' +
'''pubs.dbo.authors''' +
'INSERT #ErrFile VALUES(##ERROR)'
EXEC(#cmd)
SET #ExecError = (SELECT * FROM #ErrFile)
SELECT #ExecError AS '##ERROR'
http://msdn.microsoft.com/en-us/library/ms191503.aspx
i would advice to create table with unique name before bulk inserting.