I have an Access database in which I drop the table and then create the table afresh. However, I need to be able to test for the table in case the table gets dropped but not created (i.e. when someone stops the DTS package just after it starts -roll-eyes- ). If I were doing this in the SQL database I would just do:
IF (EXISTS (SELECT * FROM sysobjects WHERE name = 'Table-Name-to-look-for'))
BEGIN
drop table 'Table-Name-to-look-for'
END
But how do I do that for an Access database?
Optional answer: is there a way to have the DTS package ignore the error and just go to the next step rather than checking to see if it exists?
SQL Server 2000
I'm not sure whether you can query the system objects table in an Access database from a DTS package.
If that doesn't work, why not just try doing a SELECT * from the Access table in question and then catch the error if it fails?
Try the same T-SQL, but in MS ACCESS the sys objects table is called:
MSysObjects.
Try this:
SELECT * FROM MSysObjects WHERE Name = 'your_table';
and see if it works from there.
You can take a look at these tables if you go to Tools -> Options -> View (a tab) -> and check Hidden Objects, System Objects. So you can see both. If you open the table, you should see your table names, queries, etc. Do not change this manually or the DB could panic :)
Martin.
P.D.: Your If Exists should also check of object type:
IF EXISTS (SELECT * FROM sysobjects WHERE id = object_id(N'[dbo].[Your_Table_Name]') AND OBJECTPROPERTY(id, N'IsUserTable') = 1)
Microsoft Access has a system table called MSysObjects that contains a list of all database objects, including tables. Table objects have Type 1, 4 and 6.
It is important to reference the type:
... Where Name='TableName' And Type In (1,4,6)
Otherwise, what is returned could be a some object other than a table.
Related
On the ETL server I have a DW user table.
On the prod OLTP server I have the sales database. I want to pull the sales only for users that are present in the user table on the ETL server.
Presently I am using an execute SQL task to fetch the DW users into a SSIS System.Object variable. Then using a for each loop to loop through each item (userid) in this variable and via a data flow task fetch the OLTP sales table for each user and dump it into the DW staging table. The for each is taking long time to run.
I want to be able to do an inner join so that the response is quicker, but I cant do this since they are on separate servers. Neither can I use a global temp table to make the inner join, for the same reason.
I tried to collect the DW users into a comma separated string variable and then using it (via string_split) to query into OLTP, but this is also taking more time at the pre-execute phase (not sure why exactly) even for small number of users.
I also am aware of lookup transform but that too will result in all oltp rows to be brought into the dw etl server to test the lookup condition.
Is there any alternate approach to be able to do an inner join by taking the list of users into the source?
Note: I do not have write permissions on the OLTP db.
Based on the comments, I think we can use a temporary table to solve this.
Can you help me understand this restriction? "Neither can I use a global temp table to make the inner join, for the same reason."
The restriction is since oltp server and dw server are separate so can't have global temp table common to both servers. Hope makes sense.
The general pattern we're going to do is
Execute SQL Task to create a temporary table on the OLTP server
A Data Flow task to populate the new temporary table. Source = DW. Destination = OLTP. Ensure Delay Validation = True
Modify existing Data Flow. Modify source to be a query that uses the temporary table i.e. SELECT S.* FROM oltp.sales AS S WHERE EXISTS (SELECT * FROM #SalesPerson AS SP WHERE SP.UserId = S.UserId); Ensure Delay Validation = True
A long form answer on using temporary tables (global to set the metadata, regular thereafter)
I don't use temp table in SSIS
Temporary tables, live in tempdb. Your OLTP and DW connection managers likely do not point to tempdb. To be able to reference a temporary table, local or global, in SSIS you need to either define an additional connection manager for the same server that points explicitly at tempdb so you can use the drop down in the source/destination components (technically accurate but dumb). Or, you use an SSIS Variable to hold the name of the table and use the ~From Variable~ named option in source/destination component (best option, maximum flexibility).
Soup to nuts example
I will use WideWorldImporters as my OLTP system and WideWorldImportersDW as my DW system.
One-time task
Open SQL Server Management Studio, SSMS, and connect to your OLTP system. Define a global temporary table with a unique name and the expected structure. Leave your connection open so the table structure remains intact during initial development.
I used the following statement.
DROP TABLE IF EXISTS #SO_70530036;
CREATE TABLE #SO_70530036(EmployeeId int NOT NULL);
Keep track of your query because we'll use it later on but as I advocate in my SSIS answers, perform the smallest task, test that it works and then go on to the next. It's the only way to debug.
Connection Managers
Define two OLE DB Connection Managers. WWI_DW uses points to the named instance DEV2019UTF8 and WWI_OLTP points to DEV2019EXPRESS. Right click on WWI_OLTP and select Properties. Find the property RetainSameConnection and flip that from the default of False to True. This ensures the same connection is used throughout the package. As temporary tables go out of scope when the connection goes away, closing and reopening a connection in a package will result in a fatal error.
These two databases on different instances so we can't cheat and directly comingle data.
Variables
Define 4 variables in SSIS, all of type String.
TempTableName - I used a value of ##SO_70530036 but use whatever value you specified in the One-time task section.
QuerySourceEmployees - This will be the query you run to generate the candidate set of data to go into the temporary table. I used SELECT TOP (3) E.[WWI Employee ID] AS EmployeeId FROM Dimension.Employee AS E WHERE E.[Is SalesPerson] = CAST(1 AS bit);
QueryDefineTables - Remember the drop/create statements from the on-time task? We're going to use the essence of them but use the expression builder to let us dynamically swap the table name. I clicked the ellipses, ..., on the Expression section and used the following "DROP TABLE IF EXISTS " + #[User::TempTableName] + "; CREATE TABLE " + #[User::TempTableName] + "( EmployeeId int NOT NULL);" You should be able to copy the Value from the row and paste it into SSMS to confirm it works.
QuerySales - This is the actual query you're going to use to pull your filtered set of sales data. Again, we'll use the Expression to allow us to dynamically reference the temporary table name. The prettified version of the expression would look something like
"SELECT
SI.InvoiceID
, SI.SalespersonPersonID
, SO.OrderID
, SOL.StockItemID
, SOL.Quantity
, SOL.OrderLineID
FROM
Sales.Invoices AS SI
INNER JOIN
Sales.Orders AS SO
ON SO.OrderID = SI.OrderID
INNER JOIN
Sales.OrderLines AS SOL
ON SO.OrderID = SOL.OrderID
WHERE
EXISTS (SELECT * FROM " + #[User::TempTableName] + " AS TT WHERE TT.EmployeeID = SI.SalespersonPersonID);"
Again, you should be able to pull the Value from the three queries and run them independently and verify they work.
Execute SQL Task
Add an Execute SQL task to the Control Flow. I named mine SQL Create temporary table My Connection Manager is WWI_OLTP and I changed the SQLSourceType to Variable and the SourceVariable is User::QueryDefineTables
Every time your package runs, the first thing it will do is establish create the temporary table. Which is good because SSIS is a metadata driven ETL engine and the next two steps would fail if the table didn't exist.
Data Flow Task - Prime the pump
This data flow is where we'll transfer DW data back to the OLTP system so can filter in the source system.
Drag a Data Flow Task onto the Control Flow. I named mine DFT Load Temp and before you click into it, right click on the Task and find the DelayValidation property and change this from the default of False to True. Normally, a package validates all metadata before actual execution begins as the idea is you want to know everything is good before any data starts moving. Since we're using temporary tables, we need to tell the execution engine "trust us, it'll be ready"
Double click inside the Data Flow Task.
Add an OLE DB Source. I named mine OLESRC SourceEmployees I use the connection manager WWI_DW. My data access mode changes to SQL command from variable and then I select my variable User::QuerySourceEmployees
Add an OLE DB Destination. I named mine OLEDST TempTableName and double clicked to configure it. The Connection Manager is WWI_OLTP and again, since the table lives in tempdb, we can't select it from the drop down. Change the Data access mode to Table name or view name variable - fast load and then select your variable name User::TempTableName. Click the Mapping tab and ensure source columns map to destination columns.
Data Flow Task - Transfer data
Finally, we will pull our source data, nicely filtered against the data from our target system.
Add an OLE DB Source. I named it OLESRC QuerySales. The Connection Manager is WWI_OLTP. Data access mode again changes to SQL command from variable and the variable name is User::QuerySales
From here, do whatever else you need to do to make the magic happen.
Instead of having 270k rows with an unfiltered query
I have 67k as there are only 3 employees in the temporary table.
Reference package
But wait, there's more!
Close out visual studio, open it back up and try to touch something in the data flows. Suddenly, there are red Xs everywhere! Any time you close a data flow component, it fires a revalidate metadata operation and guess what, it can't do that as the connection to the temporary table is gone.
The package will run fine, it will not throw VS_NEEDSNEWMETADATA but editing/maintenance becomes a pain.
If you switched from global temporary table to local, switch the table name variable's value back to a global and then run the define statement in SSMS. Once that's done, then you can continue editing the package.
I assure you, the local temporary table does work once you have the metadata set and you use queries via variables for source/destination.
No need for the global temporary table hack, or the SET FMTONLY OFF hack (which no longer works).
Just specify the result set metadata in the SQL query with WITH RESULT SETS. eg
EXEC ('
create table #t
(
ID INT,
Name VARCHAR(150),
Number VARCHAR(15)
)
insert into #t (Id, Name, Number)
select object_id, name, 12
from sys.objects
select * from #t
')
WITH RESULT SETS
(
(
ID INT,
Name VARCHAR(150),
Number VARCHAR(15)
)
)
If you need to parameterize the query, there's a bit of a catch because there are some limitations in how SSIS discovers parameters. SSIS runs sp_describe_undeclared_parameters, which doesn't really work with batches that call sp_executesql, because sp_executesql has a very unique way it handles parameters, one which you couldn't replicate with a user stored procedure.
So to parameterize the query you'll either need to pass the parameter values into the query using the "query from variable" and SSIS expressions, or push all this TSQL into a stored procedure.
In Sql Server there's sys Schema. sys.Columns, sys.Tables.
I have a general tables which I need to rename to SysUsers, SysRoles, etc.
Is it fine to do that? I will not use Sys schema. I just will prefix tables with Sys
I find SQL Server itself do it generally
select * FROM SysColumns // NOTE its not sys.Columns
TL;DR: Don't do this.
You will have name clashes and your objects will be unusable.
I strongly recommend against this. If you have any objects where the names clashes you will not be able to reference it.
Take this simple example:
USE master;
GO
CREATE DATABASE Sillytest;
GO
USE Sillytest;
GO
SELECT *
FROM syscolumns;
GO
SELECT *
FROM dbo.syscolumns;
GO
SELECT *
FROM sys.syscolumns;
GO
CREATE TABLE dbo.syscolumns (ID int, ColumnName sysname);
GO
SELECT *
FROM syscolumns;
GO
SELECT *
FROM dbo.syscolumns;
GO
SELECT *
FROM sys.syscolumns;
GO
USE master;
GO
DROP DATABASE Sillytest;
GO
Every single reference to syscolumns, whether prefixed by dbo, sys, or not at all, references the object sys.syscolumns. Not one of those statements returns data from the (empty) user table I created dbo.syscolumns. Notice, as well, that the reference to dbo.syscolumns before I create a table of that name also works.
Yes, you can create the objects, but if the name already exists as a sys.sys{object} object, then you won't be able to use it.
Further to this, there is already an object sys.sysusers, so we actually have the answer; don't do it, you already have a clash.
Total agreement with #Larnu and I upvoted that answer. Let me add one more.
By putting a single prefix at the front of all your table names, you actually hurt your ability to search, sort, and filter, your tables. It will slow down the database. It will hurt SSMS behavior and 3rd party tools.
Don't do this, but also, don't do it with something else either; tbl, tab, none of that junk.
I am using VS 2019 and comparing 2 databases using Schema Compare. Most of the time it finds the differences just fine and replicates them across. However, on some Stored Procedures it highlights a difference because of a schema name missing. e.g. [dbo]
Example:
Left Panel (local DB)
CREATE Procedure MyNewProcedure
(
#prmParam1 int
)
Select * from TableA where Id = #prmParam1
And on the Right hand Panel (remote DB) it shows the schema name correctly:
CREATE Procedure [dbo].[MyNewProcedure]
(
#prmParam1 int
)
Select * from TableA where Id = #prmParam1
If I run the update, it will create another version of this stored procedure but it won't belong to the dbo schema - it will take on the schema name of the connection.
It only does this for a handful of stored procedures. All the rest it adds the [dbo]. to each of the create statements.
I can not figure out why as I have to manually create the SP on the remote DB and then do an Exclude for each of these in the compare so it won't delete my new SP on the remote and create the new one without the [dbo].
Anyone got any ideas or seen this before?
I don't think I am creating the original SP (local) in any different way. Just a blank New Query window and type it in and hit F5.
Thanks in advance,
Ro
I have a legacy db from an application that is no longer supported. I'm trying to deconstruct a stored procedure to make a modification, but I can't figure out where #tempimport is located. I've searched high and low through the schema, but I'm not finding anything close. This is how it's used:
SET NOCOUNT ON;
DECLARE #saleid UNIQUEIDENTIFIER
SELECT TOP 1 #saleid = [sale_id] FROM #tempimport;
Is this a T-SQL specific thing, or can I actually find the data in this table somewhere?
Tables with the # preceding the name are temporary tables.
You can find them in the tempdb database under System Databases
Tables that are prefixed with a # are temporary tables that are created in the tempdb system database.
try to find code of this table creation in you DB schema
select * from information_schema.routines
where object_definition(object_id(routine_name)) like '%#tempimport%'
try find #tempimport in schemas of neighboring DBs
try find #tempimport in your application sources if exists.
try to profile(SQL Profiler tool) your application and search #tempimport here.
Additional
#tempimport can be created by any connected application. Not only from your DB runnable code
you can research deeper and try to monitoring the moment of #tempimport creation. Example
select left(name, charindex('_',name)-1)
from tempdb..sysobjects
where charindex('_',name) > 0 and
xtype = 'u' and not object_id('tempdb..'+name) is null
and left(name, charindex('_',name)-1) = '#tempimport'
source: Is there a way to get a list of all current temporary tables in SQL Server?
I have a query in classic asp where SQL statement is this:
Select * from active_Case
I verified in the DB connection it is using and found there is no such table / view. But a table does exist by the name of Cases. Internally it appears to be selecting from this table itself.
Actually this is somebody else's code. Thus I am not sure how is it possible. Is it really possible or am I missing something?
this will give you the base table name
select name, base_object_name
from sys.synonyms
where name = 'active_Case'
other than tables and view you can even check in User defined table type under types. or there might be chance your table is having a schema other than 'dbo.'