I have a query that I want to be able to use across database schemas. Right now it is written so that I need to replace the schema in several places of the query. How do I set that up as a variable so that all I need to do is change it in one place?
You can do this with Dynamic SQL:
DECLARE #sql VARCHAR(MAX)
,#schema VARCHAR(255) = 'dbo'
SET #sql = 'SELECT *
FROM '+#schema+'.yourTable
'
EXEC (#sql)
You could use this in a cursor to loop through schema's:
DECLARE #Iterator varchar(255)
,#strSQL varchar(MAX)
DECLARE xyz CURSOR
FOR
--Select stuff to iterate over
SELECT name
FROM sys.schemas
OPEN xyz
FETCH NEXT FROM xyz
INTO #Iterator
WHILE ##FETCH_STATUS = 0
BEGIN
--Do stuff
SET #strSQL = 'SELECT *
FROM '+#Iterator+'.yourTable
'
Exec (#strSQL)
FETCH NEXT FROM xyz
INTO #Iterator
END
CLOSE xyz
DEALLOCATE xyz
GO
To test your dynamic SQL statements, you can change EXEC to PRINT and ensure that the resulting query is as you intended.
Synonyms might be the answer to your question.
You can use dynamic SQL. Here is an example -
DECLARE #Column varchar(25)
DECLARE #sqlStmt varchar(max)
SET #Column = 'MyColumn'
SET #sqlStmt = N'SELECT ' + #Column + ' FROM MyTable'
EXEC (#sqlStmt)
Related
I'm using a linked server and finding it very painful to write queries like this:
select * from [10.150.10.109].lhf.[dbo].[TABLE_NAME]
Is it possible to use a synonym for something like this:
CREATE SYNONYM [DataRelay] FOR [10.150.10.109].[lhf].[dbo]
in order to be able to query like this:
select * from DataRelay.TABLE_NAME
Without the capabilities of Intellisense, this is just painful...
No, there is no short hand for linked servers, however, you can alias tables in your queries to make it a bit easier.
select * from [10.150.10.109].lhf.[dbo].[TABLE_NAME] T
WHERE
T.FieldName=1
OR
T.FieldName=2
Now that I had a minute what I was saying in my comment is that you cannot create a synonym for just part of an object path as you desire. But you can dynamically script the drop and creation of synonyms for any object in your remote database pretty easily. here is an example of how to do if for user tables. For other objects you can use the sys.objects instead of sys.table system view.
Technique key words for more learning. Dynamic SQL, cursor, schema views.
DECLARE #ServerAndDB SYSNAME = '[10.150.10.109].[lhf]'
DECLARE #SynonymSchema SYSNAME = '[syn]'
DECLARE #ObjectPath NVARCHAR(1000)
DECLARE #SynonymName NVARCHAR(1000)
DECLARE CursorName CURSOR FOR
SELECT
#ServerAndDB + QUOTENAME(SCHEMA_NAME(t.schema_id)) + '.' + QUOTENAME(t.name) as ObjectPath
,#SynonymSchema + '.' + QUOTENAME(t.name) as SynonymName
FROM
[10.150.10.109].[lhf].sys.tables t
WHERE
t.type = 'U'
OPEN CursorName
FETCH NEXT FROM CursorName
INTO #ObjectPath, #SynonymName
WHILE ##FETCH_STATUS = 0
BEGIN
BEGIN TRY
DECLARE #SQL NVARCHAR(MAX)
IF EXISTS (SELECT * FROM sys.synonyms WHERE object_id = OBJECT_ID(#SynonymName))
BEGIN
SET #SQL = 'DROP SYNONYM ' + #SynonymName
EXECUTE sp_executesql #SQLString
SET #SQL = ''
END
SET #SQL = 'CREATE SYNONYM ' + #SynonymName + ' FOR ' + #ObjectPath
EXECUTE sp_executesql #SQLString
SET #SQL = ''
END TRY
BEGIN CATCH
--Can do error handling here
END CATCH
FETCH NEXT FROM CursorName
INTO #ObjectPath, #SynonymName
END
CLOSE CursorName
DEALLOCATE CursorName
I have a problem with treating table name as variable as I need to put the results to different table each month automatically (without using any advanced procedures to make this query dynamic). Can somebody help me to modify this code and make it work?
declare #exp_dte as date;
set #exp_dte='2015-12-31';
print (#exp_dte);
declare #tab_mth as nvarchar(max);
set #tab_mth=year(#exp_dte)*100+month(#exp_dte);
print (#tab_mth);
declare #tab_name as nvarchar(max)
set #tab_name='mis_anl.dbo.BIK_' + #tab_mth
print (#tab_name);
IF OBJECT_ID (N'#tab_name', N'U') IS NOT NULL
begin
drop table #tab_name
end
select distinct
*
into #tab_name
from table_x
You have to use dynamic SQL to set name at runtime:
DECLARE #exp_dte DATE = '2015-12-31';
DECLARE #tab_name SYSNAME = '[dbo].' + QUOTENAME('BIK_' + FORMAT(#exp_dte, 'yyyyMM'));
IF OBJECT_ID (#tab_name, N'U') IS NOT NULL
BEGIN
EXEC('DROP TABLE' + #tab_name);
END
DECLARE #sql NVARCHAR(MAX) = N'SELECT DISTINCT *
INTO #tab_name
FROM table_x';
SET #sql = REPLACE(#sql, '#tab_name', #tab_name);
EXEC [dbo].[sp_executesql] #sql;
LiveDemo
Remarks:
Try to be more conscise
You could use FORMAT to get yyyyMM (SQL Server 2012+)
Always QUOTENAME generated identifiers to avoid SQL Injection attacks
I strongly recommend to read The Curse and Blessings of Dynamic SQL especially CREATE TABLE #tbl.
use dynamic sql ,you cant user table names as variables
declare #exp_dte as date;
set #exp_dte='2015-12-31';
declare #tab_mth as nvarchar(max);
set #tab_mth=year(#exp_dte)*100+month(#exp_dte);
declare #tab_name as nvarchar(max)
set #tab_name='mis_anl.dbo.BIK_' + #tab_mth
declare #sql1 nvarchar(max)
set #sql1='drop table '+#tab_name;
IF exists(select 1 from information_schema.tables where table_name=#tab_name)
begin
exec(#sql1);
end
declare #sql nvarchar(max)
set #sql='
select distinct
*
into '+#tab_name+'
from table_x'
exec (#sql)
Say I want to run the following:
update users set age = 10
on databases:
db1, db2, db3
All on the same server, I want to loop through and perform the same action.
Currently I am doing this manually using management studio via the dropdown.
Hoping there is a better way.
You could probably do it with dynamic SQL. Something like so:
create table #dbs (db_name sysname not null)
insert into #dbs values ('db1'),('db2'),('db3')
declare curs cursor for
select db_name from #dbs
declare #db sysname, #sql nvarchar(max)
open curs
while(1=1)
begin
fetch next from curs into #db
if (##fetch_status <> 0)
break
set #sql = 'update ' + quotename(#db) + '.dbo.users set age = 10'
exec(#sql)
end
close curs
deallocate curs
drop table #dbs
Not sure about doing it 'dynamically', i.e. a FOR-EACH style loop on all the databases in a server, but this should work:
USE db1
update users set age = 10
GO
USE db2
update users set age = 10
GO
USE db3
update users set age = 10
Designate a server as a central management server and then add the other servers to the server group. Then you can run the update on all databases within the group. http://msdn.microsoft.com/en-us/library/bb934126.aspx
use [WWAUTHxxx__] -- a db containing active databases.
set nocount on
declare #Catalog as nvarchar(32)
declare #LibraryName as varchar(255)
declare #dbtable as varchar(50)
declare #retval as nvarchar(50)
declare #sSQL as nvarchar(max)
declare #parmdef as nvarchar(500)
declare #retvalout as nvarchar(50)
Declare Library_Cursor Cursor for
select top(1000) xCatalog, xLibraryName
from Active_DBs
order by xcatalog
Open Library_Cursor;
Fetch Next from Library_Cursor into #Catalog, #LibraryName
while ##Fetch_status = 0
begin
set #dbTable = #Catalog + '.dbo.las_circperiods'
set #ParmDef = N'#retvalOUT int OUTPUT';
set #sSQL = N'Select #retvalout = count(*) from ' + #dbtable
+ ' where xlastcircdate is null'
exec sp_executesql #ssql,#parmdef,#retvalout=#retval output
if #retval > 0 -- check/print Sql and then activate.
-- I like checking to see the potentially affected databases.
begin
print #Catalog + ',' + #LibraryName + ',' + #retval
set #ssql = N'update ' + #dbTable
+ ' set xlastcircdate = '''' '
+ ' where xlastcircdate is null'
-- print #ssql -- View what you might will do
exec sp_executesql #ssql -- Do it.
end
Fetch Next from Library_Cursor into #Catalog, #LibraryName
end;
close Library_cursor
Deallocate Library_cursor
I am wondering why I cannot use variable column name like that:
declare #a as varchar;
set #a='TEST'
select #a from x;
Thank you
You can't do it because SQL is compiled before it knows what the value of #a is (I'm assuming in reality you would want #a to be some parameter and not hard coded like in your example).
Instead you can do this:
declare #a as varchar;
set #a='TEST'
declare #sql nvarchar(max)
set #sql = 'select [' + replace(#a, '''', '''''') + '] from x'
exec sp_executesql #sql
But be careful, this is a security vulnerability (sql-injection attacks) so shouldn't be done if you can't trust or well clean #a.
Because it is not allowed.
Insted of this you could use dynamic sql query:
declare #a as varchar;
set #a='TEST'
exec ('select ' + #a + ' from x')
Because the column names are resolved at compile time not at run time for the SQL statement.
use sp_executesql for this
Example
SET #SQLString = N'SELECT *
FROM table1
WHERE timet = #time and items in (#item)';
DECLARE #SQLString nvarchar(500);
DECLARE #ParmDefinition nvarchar(500);
SET #ParmDefinition = N'#time timestamp,
#item varchar(max) ';
EXECUTE sp_executesql
#SQLString
,#ParmDefinition
,#time = '2010-04-26 17:15:05.667'
,#item = '''Item1'',''Item2'',''Item3'',''Item4'''
;
If there are not too many columns to chose, how about a CASE WHEN statement?
DECLARE #ColName VARCHAR(50) = 'Test1'
SELECT [Foo], [Bar],
CASE
WHEN #ColName = 'Test1' THEN [Test1]
WHEN #ColName = 'Test2' THEN [Test2]
WHEN #ColName = 'Test3' THEN [Test3]
WHEN #ColName = 'Test4' THEN [Test4]
ELSE [TestDefault]
END [TestResult]
FROM [TableName];
This avoids using any EXEC.
I'm securing the DB by only allowing interaction with the DB through a series of Sprocs; pretty common fare.
I've dug up and modified a script which loops through and assigns the user EXECUTE permission for all non-system SProcs. It works a treat except that I'd ideally like to add it to the Master DB so that I can easily use it for any subsequent projects. Yes, I could save simple as a .sql file but I'd prefer it this way.
The problem is that I don't know how to dynamically refer to objects in another DB. For example, I can easily query on MyDB.dbo.INFORMATION_SCHEMA.ROUTINES, but if the DB name is dynamic (e.g. #MyDBName), how can I query the objects in this DB?
Edit: Thanks to the posters below, I now have a working solution:
USE [master]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[spGrantExec]
#User sysname,
#DB varchar(50),
#Target varchar(50)
AS
/*---------------------------- SQL 2005 + -------------------------------*/
SET NOCOUNT ON
-- 1 - Variable declarations
DECLARE #SQL varchar(8000)
-- 2 - Create temporary table
Set #SQL =
'USE #DB
DECLARE #MAXOID int
DECLARE #OwnerName varchar(128)
DECLARE #ObjectName varchar(128)
DECLARE #CMD1 varchar(8000)
CREATE TABLE #StoredProcedures
(OID int IDENTITY (1,1),
StoredProcOwner varchar(128) NOT NULL,
StoredProcName varchar(128) NOT NULL)
-- 3 - Populate temporary table
INSERT INTO #StoredProcedures (StoredProcOwner, StoredProcName)
SELECT ROUTINE_SCHEMA, ROUTINE_NAME
FROM INFORMATION_SCHEMA.ROUTINES
WHERE ROUTINE_NAME LIKE ''' + #Target + '%''
AND ROUTINE_TYPE = ''PROCEDURE''
-- 4 - Capture the #MAXOID value
SELECT #MAXOID = MAX(OID) FROM #StoredProcedures
-- 5 - WHILE loop
WHILE #MAXOID > 0
BEGIN
-- 6 - Initialize the variables
SELECT #OwnerName = StoredProcOwner,
#ObjectName = StoredProcName
FROM #StoredProcedures
WHERE OID = #MAXOID
-- 7 - Build the string
SELECT #CMD1 = ''GRANT EXEC ON '' + ''['' + #OwnerName + '']'' + ''.'' + ''['' + #ObjectName + '']'' + '' TO #user''
-- 8 - Execute the string
Print #CMD1
EXEC(#CMD1)
-- 9 - Decrement #MAXOID
SET #MAXOID = #MAXOID - 1
END
-- 10 - Drop the temporary table
DROP TABLE #StoredProcedures'
Set #SQL = REPLACE(REPLACE(REPLACE(#SQL, '#DB', #DB), '#User', #User), '#Target', #Target)
--Select #SQL
--Print #SQL
Exec (#SQL)
SET NOCOUNT OFF
Similiar to #Cade's answer, the way to do this is to use dynamic sql. Before each call to a database table, add '#DbName.' Then replace the #DbName with the actual database name (the database name can't be passed as a variable in SQL, so you have to do the replace).
Also Cursors are normally considered evil for performance reasons, however using one in this case makes sense. For one, it would greatly simplify the procedure, plus since you're only going to run this once during application updates, you probably won't notice a performance hit, even if it added an extra second or two (which I doubt it would add anywhere near that much).
ALTER PROCEDURE [dbo].[spGrantExec]
#User SysName,
#DbName VarChar(512)
AS
BEGIN
DECLARE #Sql VarChar(1024)
SET #Sql = 'DECLARE #OwnerName varchar(128)
DECLARE #ObjectName varchar(128)
DECLARE #Cmd1 VarChar(128)
DECLARE ProcCursor CURSOR FOR
SELECT ROUTINE SCHEMA, ROUTINE NAME
FROM #DbName.INFORMATION SCHEMA.ROUTINES
WHERE ROUTINENAME NOT LIKE ''dt %'' AND ROUTINE TYPE = ''PROCEDURE''
OPEN ProcCursor
FETCH NEXT FROM ProcCursor INTO #OwnerName, #ObjectName
WHILE ##FETCH STATUS = 0
BEGIN
SET #CMD1 = ''GRANT EXEC ON '' + ''['' + #OwnerName + '']'' + ''.'' + ''['' + #ObjectName + '']'' + '' TO '' + ''#user''
EXEC (#CMD1)
FETCH NEXT FROM ProcCursor INTO #OwnerName, #ObjectName
END
CLOSE ProcCursor
DEALLOCATE ProcCursor
'
SET #Sql = Replace(Replace(#Sql, '#DbName', #DbName), '#user', #User)
EXEC (#Sql)
END
You can call this using: EXEC [spGrantExec] 'bob', 'Northwind'
Sorry the spacing is a little off in the sp. Developed using Sql 2005.
I found another technique, which I think is cleaner:
SELECT #sql = 'CREATE VIEW ...'
SELECT #sp_executesql = quotename(#dbname) + '..sp_executesql'
EXEC #sp_executesql #sql
This relies on setting the database context by calling sp_executesql in the other database (just like one could call an SP in any database).
In your case it would be equivalent to:
SELECT #sp_executesql = quotename(#dbname) + '..sp_executesql'
EXEC #sp_executesql #CMD1
You can use the double exec technique.
In your case, instead of just:
EXEC(#CMD1)
You would have:
SET #CMD1 =
'USE OtherDatabase;
EXEC (''' + REPLACE(#CMD1, '''', '''''') + ''')'
EXEC(#CMD1)