I have a ETL project that I need to load data from some 50K Access .MDB databases in a folder to sql server. Problem with those 50K databases files is that they have different schemas and I need the ETL process to be able to identify the differences and respond correctly.
For example, in some of the .MDB files there are table A, B and C. However in some other tables there are only table A and B (Same table A and B as compared to the other tables, just table C is missing). I need to put a check on each OLE DB source to see what tables are there to achieve logic like IF table A exists, load table A, otherwise, bypass the load.
I've done my googling and searched SO but all the error handling or check methods I could find are for the execute SQL task or data conversion task. So if anyone could shed some light on solution to my above case, I would be deeply appreciated.
Thanks.
In a nutshell - SSIS assumes that metadata does not change.
However, with some tricks, this restriction can be reduced; below is the list of suggested tricks:
Test for existence of specific table (see example here How to use SQL to query the metadata in Microsoft Office Access? Like SQL Server's sys.tables, sys.columns etc) and based on the result - do conditional execution of the following tasks.
All SQL requests to MS Access tables should have DelayValidation property set to True. Reason - postpone SQL command validation from package start to specific task execution. Some tasks (for missing tables) will not be executed; thus, it will not be validated and will not fire validation error.
Related
I am using select statement in excel source to select just specific columns data from excel for import.
But I am wondering, is it possible to select data such way when I select for example column with name: Column_1, but if this column is not exists in excel then it will try to select column with name Column_2? Currently if Column_1 is missing, then data flow task fails.
Use a Script task and write .net code to read the excel file and then perform the check for the Column_1 availability in the file. If the column does not present then use Column_2 as input. Script Task in SSIS can act as a source.
SSIS is metadata based and will not support dynamic metadata, however you can use Script Component as #nitin-raj suggested to handle all known source columns. There is a good post below on how it can be done.
Dynamic File Connections
If you have many such files that can have varying columns then it is better to create a custom component.However, you cannot have dynamic metadata even with custom component, the set of columns should be known upfront to SSIS.
If the list of columns keep changing and you cannot know in advance what are expected columns then you are better off handling the entire thing in C#/VB.Net using Script Task of control flow
As a best practice, because SSIS meta data is static, any data quality and formatting issues in source files should be corrected before ssis data flow task runs.
I have seen this situation before and there is a very simple fix. In the beginning of your ssis package, using a file task to create copy of the source excel file and then run a c# script or execute a powershell to rename the columns so that if column 1 does not exist, it is either added at the appropriate spot in excel file or in case the column name is wrong is it corrected.
As a result of this, you will not need to refresh your ssis meta data every time it fails. This is a standard data standardization practice.
The easiest way is to add two data flow tasks, one data flow for each Excel source select statement and use precedence constraints to execute the second data flow when the first one fails.
The disadvantage of this approach is that if the first data flow task fails for another reason, it will also try to execute the second one. You will need some advanced error handling to check if the error is thrown due to missing columns or not.
But if have a similar situation, I will use a Script Task to check if the column exists and build the SQL command dynamically. Note that this SQL command must always return the same metadata (you must use aliases).
Helpful links
Overview of SSIS Precedence Constraints
Working with Precedence Constraints in SQL Server Integration Services
Precedence Constraints
Problem:
I need to get data sets from CSV files into SQL Server Express (SSMS v17.6) as efficiently as possible. The data sets update daily into the same CSV files on my local hard drive. Currently using MS Access 2010 (v14.0) as a middleman to aggregate the CSV files into linked tables.
Using the solutions below, the data transfers perfectly into SQL Server and does exactly what I want. But I cannot figure out how to refresh/update/sync the data at the end of each day with the newly added CSV data without having to re-import the entire data set each time.
Solutions:
Upsizing Wizard in MS Access - This works best in transferring all the tables perfectly to SQL Server databases. I cannot figure out how to update the tables though without deleting and repeating the same steps each day. None of the solutions or links that I have tried have panned out.
SQL Server Import/Export Wizard - This works fine also in getting the data over to SSMS one time. But I also cannot figure out how to update/sync this data with the new tables. Another issue is that choosing Microsoft Access as the data source through this method requires a .mdb file. The latest MS Access file formats are .accdb files so I have to save the database in an older .mdb version in order to export it to SQL Server.
Constraints:
I have no loyalty towards MS Access. I really am just looking for the most efficient way to get these CSV files consistently into a format where I can perform SQL queries on them. From all I have read, MS Access seems like the best way to do that.
I also have limited coding knowledge so more advanced VBA/C++ solutions will probably go over my head.
TLDR:
Trying to get several different daily updating local CSV files into a program where I can run SQL queries on them without having to do a full delete and re-import each day. Currently using MS Access 2010 to SQL Server Express (SSMS v17.6) which fulfills my needs, but does not update daily with the new data without re-importing everything.
Thank you!
You can use a staging table strategy to solve this problem.
When it's time to perform the daily update, import all of the data into one or more staging tables. Execute SQL statement to insert rows that exist in the imported data but not in the base data into the base data; similarly, delete rows from the base data that don't exist in the imported data; similarly, update base data rows that have changed values in the imported data.
Use your data dependencies to determine in which order tables should be modified.
I would run all deletes first, then inserts, and finally all updates.
This should be a fun challenge!
EDIT
You said:
I need to get data sets from CSV files into SQL Server Express (SSMS
v17.6) as efficiently as possible.
The most efficient way to put data into SQL Server tables is using SQL Bulk Copy. This can be implemented from the command line, an SSIS job, or through ADO.Net via any .Net language.
You state:
But I cannot figure out how to refresh/update/sync the data at the end
of each day with the newly added CSV data without having to re-import
the entire data set each time.
It seems you have two choices:
Toss the old data and replace it with the new data
Modify the old data so that it comes into alignment with the new data
In order to do number 1 above, you'd simply replace all the existing data with the new data, which you've already said you don't want to do, or at least you don't think you can do this efficiently. In order to do number 2 above, you have to compare the old data with the new data. In order to compare two sets of data, both sets of data have to be accessible wherever the comparison is to take place. So, you could perform the comparison in SQL Server, but the new data will need to be loaded into the database for comparison purposes. You can then purge the staging table after the process completes.
In thinking further about your issue, it seems the underlying issue is:
I really am just looking for the most efficient way to get these CSV
files consistently into a format where I can perform SQL queries on
them.
There exist applications built specifically to allow you to query this type of data.
You may want to have a look at Log Parser Lizard or Splunk. These are great tools for querying and digging into data hidden inside flat data files.
An Append Query is able to incrementally add additional new records to an existing table. However the question is whether your starting point data set (CSV) is just new records or whether that data set includes records already in the table.
This is a classic dilemma that needs to be managed in the Append Query set up.
If the CSV includes prior records - then you have to establish the 'new records' data sub set inside the CSV and append just those. For instance if you have a sequencing field then you can use a > logic from the existing table max. If that is not there then one would need to do a NOT compare of the table data with the csv data to identify which csv records are not already in the table.
You state you seek something 'more efficient' - but in truth there is nothing more efficient than a wholesale delete of all records and write of all records. Most of the time one can't do that - but if you can I would just stick with it.
I have been working on creating/loading data into a database for a school project and have been having some issues with Merge Join. I’ve researched many issues the others have had with Merge Join and typically solve my own problems but this one is a bit tricky. I’ve created an SSIS package that should pull a column from a table in Access (this column contains duplicate names to which I utilize a sort later on in the data flow) as well as pull another column from a table in my SQL Server database. For both of these OLE DB Sources I have tried using the simple method of selecting the table through the data access mode but I thought perhaps this was contributing to many warning messages because it would always pull everything from the table as opposed to the one column from each that I wanted. I am now using the SQL Command option with an extremely simple query (see below).
SELECT DISTINCT Name
FROM NameTable
For both OLE DB sources the query is the same except for the parameters selected. Following the source, I have a data conversion on each (because I found that Merge Join is a pansy when the data types don’t match) and I convert the Access one from DT_WSTR to DT_STR, while the SQL Server source is converted from DT_I4 to DT_STR. I then follow both with a sort, passing through the copy of Name and Tid, checking the “removing sorts with duplicate rows” option. Following that step, I then begin utilizing Merge Join with the Access source being my left input and the SQL Server Source (by source I am just referring to the side of the data flow, you’ll see in the image below) being the right input. Below I will also show how I am configuring the Merge Join, in case I’m doing it wrong. Lastly, I have my OLE DB Destination setup to drop this data into a table with the following columns, PrimaryKey column (it auto increments as new data is inserted), the Name column and the Tid column.
When I run the columns it says that it succeeds with no errors. I check my database and nothing has been written, I also note that in SSIS it says 0 rows written. I’m not sure what is going on as I enable the data viewers in between the sorts and the merge join and can see the data coming out both pipelines. Another important thing to note is that when I enable the data viewer after the Merge Join, it never shows up when I run the package, only the two after sort appear. At first I thought maybe the data wasn’t coming out of the Merge Join so I experimented with placing derive columns after the Merge Join and sure enough, the data does flow through. Even with those extra things in between the Merge Join and Destination, the data viewers never pop up. I mention this because I suspect that this is part of the problem. Below are also the messages that SSIS spits out after I run the package.
SSIS messages:
SSIS package "C:\Users\Liono\Documents\Visual Studio 2015\Projects\DataTest6\Package.dtsx" starting.
Information: 0x4004300A at Data Flow Task, SSIS.Pipeline: Validation phase is beginning.
Information: 0x4004300A at Data Flow Task, SSIS.Pipeline: Validation phase is beginning.
Information: 0x40043006 at Data Flow Task, SSIS.Pipeline: Prepare for Execute phase is beginning.
Information: 0x40043007 at Data Flow Task, SSIS.Pipeline: Pre-Execute phase is beginning.
Information: 0x4004300C at Data Flow Task, SSIS.Pipeline: Execute phase is beginning.
Information: 0x40043008 at Data Flow Task, SSIS.Pipeline: Post Execute phase is beginning.
Information: 0x4004300B at Data Flow Task, SSIS.Pipeline: "OLE DB Destination" wrote 0 rows.
Information: 0x40043009 at Data Flow Task, SSIS.Pipeline: Cleanup phase is beginning.
SSIS package "C:\Users\Liono\Documents\Visual Studio 2015\Projects\DataTest6\Package.dtsx" finished: Success.
The program '[9588] DtsDebugHost.exe: DTS' has exited with code 0 (0x0).
Lastly, I did ask a somewhat similar question and solved it on my own by using one source with the right SQL query, but the same thing doesn’t apply here because I’m pulling from two different sources and I am having issues with the Merge Join this time around. The code I used last time:
SELECT a.T1id,
b.T2id,
c.Nameid
FROM Table1 AS a join
Table2 AS b
On a.T1id = b.T2id,
Name AS c
ORDER BY a.[T1id] ASC
I post this because, maybe someone might know of a way to right some SQL that will allow me to forgo using Merge Join again, where I can somehow grab both sets of data and join them, then dump them in my table in SQL Server.
As always, I greatly appreciate your help and if there are any questions of clarifications that need to be made, please ask and I will do my best to help you help me.
Thanks!
I have a database1 which has more than 500 tables and I have database2 which also has the same number of tables and in both the databases the name of tables are same.. some of the tables have different table definitions, for example a table reports in database1 has 9 columns and the table reports in database2 has 10.
I want to copy all the data from database1 to database2 and it should overwrite the same data and append the columns if structure does not match. I have tried the import export wizard in SQL Server 2008 but it gives an error when it comes to the last step of copying rows. I don't have the screen shot of that error right now, it is my office PC. It says that error inserting into the readonly column xyz, some times it says that vs_isbroken, for the read only column error as I mentioned a enabled the identity insert but it did not help..
Please help me. It is an opportunity in my office for me.
SSIS and SQL Server 2008 Wizards can be finicky tools.
If you get a "can't insert into column ABC", then it could be one of the following:
Inserting into a PK column -> when setting up the mappings, you need to indicate to overwrite the value
Inserting into a column with a smaller range -> for example from nvarchar(256) into nvarchar(50)
Inserting into a calculated column (pointed out by #Nick.McDermaid)
You could also get issues with referential integrity if your database uses this (most do).
If you're going to do this more often, then I suggest you build an SSIS package instead of using the wizard tooling. This way you will see warnings on all sorts of issues like the ones I've described above. You can then run your package on demand.
Another suggestion I would make, is that you insert DB1 into "stage" tables in DB2. These tables should have no relational integrity and will allow you to break the process into several steps as follows.
Stage the data from DB1 into DB2
Produce reports/queries on issues pertinent to your database/rules
Merge the data from stage tables into target tables using SQL
That last step is where you can use merge statements, or simple insert/updates depending on a key match. Using SQL here in the local database is then able to use set theory to manage the overlap of the two sets and figure out what is new or to be updated.
SSIS "can" do this, but you will not be able to do a bulk update using SSIS, whereas with SQL you can. SSIS would do what is known as RBAR (row by agonizing row), something slow and to be avoided.
I suggest you inform your seniors that this will take a little longer to ensure it is reliable and the results reportable. Then work step by step, reporting on each stages completion.
Another two small suggestions:
Create _Archive tables of each of the stage tables and add a Tstamp column to each. Merge into these after the stage step which will allow you to quickly see when which rows were introduced into DB2
After stage and before the SQL merge step, create indexes on your stage tables. This will improve the merge performance
Drop those Indexes after each merge, this will increase the bulk insert Performance
Basic on Staging (response to question clarification):
Links:
http://www.codeproject.com/Articles/173918/How-to-Create-your-First-SQL-Server-Integration-Se
http://www.jasonstrate.com/tag/31daysssis/
http://blogs.msdn.com/b/andreasderuiter/archive/2012/12/05/designing-an-etl-process-with-ssis-two-approaches-to-extracting-and-transforming-data.aspx
Staging is the act of moving data from one place to another without any checks.
First you need to create the target tables, the schema should match the source tables.
Open up BIDS and create a new Project and in it a new SSIS package.
In the package, create a connection for the source server and another for the destination.
Then create a data flow step, in the step create a data source for each table you want to copy from.
Connect each source to a new data destination and set the appropriate connection and table.
When done, save and do a test run.
Before the data flow step, you might like to add a SQL step that will truncate all the target tables.
If you're open to using tools then what about using something like Red Gate Sql Compare and Red Gate SQL Data Compare?
First I would use data compare to manage the schema differences, add the new columns you want to your destination database (database2) from the source (database1). Then with data compare you match the contents of the tables any columns it can't match based on names you specify how to handle. Then you can pick and choose what data you want to copy from your destination. So you'll see what data is new and what's different (you can delete data in the destination that's not in the source or ignore it). You can either have the tool do the work or create you a script to run when you want.
There's a 15 day trial if you want to experiment.
Seems like maybe you are looking for Replication technology as is offered by SQL Server Replication.
Well, if i understood your requirement correctly, you need to make database2 a replica of database1. Why not take a full backup of database1 and restore it as database2? Your database2 will be exactly what database1 is at the time of backup.
I am new to SSIS.I got the task have according to the scenario as explained.
Scenario:
I have two databases A and B on different machines and have around 25 tables and 20 columns with relationships and dependencies. My task is to create a database C with selected no of tables and in each table I don't require all the columns but selected some. Conditions to be met are that the relationships should be intact and created automatically in new database.
What I have done:
I have created a package using the transfer SQL Server object task to transfer the tables and relationships.
then I have manually edited the columns that are not required
and then I transferred the data using the data source and destination
My question is: can I achieve all these things in one package? Also after I have transferred the data how can I schedule the package to just transfer the recently inserted rows in the database to the new database?
Please help me
thanks in advance
You can schedule the package by using a SQL Server Agent Job - one of the options for a job step is run SSIS package.
With regard to transferring new rows, I would either:
Track your current "position" in another table, assumes you have either an ascending key or a time stamp column - load the current position into an SSIS variable, use this variable in the WHERE statement of your data source queries.
Transfer all data across into "dump" copies of each table (no relationships/keys etc required just the same schema) & use a T-SQL MERGE statement to load new rows in, then truncate "dump" tables.
Hope this makes sense - its a bit difficult to get across in writing.