The Real MTCS SQL Server 2008 Exam 70/432 Prep Kit- P67 pptx

This page intentionally left blank 313 Exam objectives review: ˛ Summary of Exam Objectives ˛ Exam Objectives Fast Track ˛ Exam Objectives Frequently Asked Questions ˛ Self Test ˛ Self Test Quick Answer Key Exam objectives in this chapter: Bulk Copying Data  Distributed Queries  SQL Server Integration Services  Alternative ETL Solutions  ETL Techniques Chapter 8 MCTS SQL Server 2008 Exam 432 314 Chapter8•ETLTechniques Introduction The ETL (extract/transform/loading) process is generally done using SQL Server Integration Services (SSIS). Other methods for ETL in SQL Server are available, such as BCP, Select/Into, and insert/select. You can also write custom code using ASP.Net or other languages. This chapter covers all of the aspects and methods for performing ETL with SQL server, from BCP to SQL Server integration Services. Distributed queries and transactions are also covered in this chapter, as well as setting up and using a linked server for cross-server communications and/or queries. Setting up systems to work correctly with distributed queries can be difficult, and this chapter will help to demystify the process. Understanding ETL Organizations often have more than just one database. Organizations also often need to share data between those databases in-house as well as to exchange data with business partners. Therefore, organizations need tools to move data between databases, across platforms, and often even between different businesses. As the data moves from one database to another, there is also often a need to perform some manipulation or transformation on the data. The process of extracting data from a data source, transforming the data to meet your needs, and loading the data into a destination is known more generally as extract, transform, and load, or more simply, ETL. SQL Server provides a wide array of tools to move data. Exactly what data these tools move and how they do it varies significantly. The data could be an entire database, such as the Copy Database Wizard; a specific set of rows, such as the BCP, BULK INSERT, and OPENROWSET commands; or an extremely complex set of data movements as defined by an SSIS package. In this section, we will review all of these tools. We’ll start by looking at tools for bulk copying data. Bulk Copying Data When you want to move a lot of data into or out of SQL server, you will likely find that the most efficient and best-performing tools are those that facilitate the bulk loading of data. The bulk loading tools are typically used to move data between flat files (e.g., a .csv file) and SQL Server, but it is possible to use the bulk copy operations with data sources other than flat files by using certain programming techniques. Regardless of what the data source is, though, the whole point of using the bulk copy tools is performance. Organizations use bulk loading techniques ETL Techniques • Chapter 8 315 when they want to move a large number of rows as quickly as possible, and with as little impact on their servers as possible. Optimizing that performance can be a bit of an art, but we’ll talk about some performance techniques at the end of this section. Before we get into performance, however, let’s look at the first of the bulk load tools, BCP. Using BCP BCP (short for Bulk Copy Program) is a command line utility that you can use to import data from a file into SQL Server, export data from SQL Server into a file, and generate format files for use by BCP and other bulk copy tools. BCP has been available in many versions of SQL Server. Before tools like SSIS existed, BCP was the only available means for easily getting data into or out of SQL Server. BCP is limited to working with flat files and SQL Server. If you want to get data from another data source (e.g., and Oracle database) into SQL Server, BCP is not the most direct means for this type of data transfer. SSIS would be a better tool for this type of transfer. BCP is a useful tool, however, if you have flat files (delimited, fixed format, etc.) to either extract data from or load data into. Ex a m Wa r n i n g Remember that BCP can work with only text files and SQL Server. It can’t be used to move data directly from one SQL Server to another. The data must first be exported from one database to a flat file and then imported to the destination from the flat file. So let’s start with the basic structure of the BCP utility: bcp {dbtable | query} {in | out | queryout | format} datafile [option, n] You can find explanations of these in Table 8.1. 316 Chapter8•ETLTechniques Syntax Element Description dbtable If you will be importing or exporting data from a SQL Table or View, this is the qualified object name. For example, to import into the Person table in the Person schema of the AdventureWorks2008 data- base, this would be: [AdventureWorks2008].[Person].[Person] The bcp command allows you to tell it which SQL Server instance to connect to, but does not allow you to specify which database. If the table you wish to work with is not in the connections default data- base, you will need to qualify the object name using the database.schema.object format. If you will be importing to a view, you need to make sure that the view supports inserts. dbtable can be used with the in, out, or format options. This means that you can import to the table (in) or export from it (out). query You can export from a query rather than a specific table or view. You need to enclose the query in double quotes (“) and use single quotes for any character literals inside the query. query can be used with the queryout and format options. You cannot import to a query. in Use this option when you will be importing data into the dbtable specified. out Use this option when you will be exporting data from the dbtable specified. queryout Use this option when you will be exporting data from the specified query. Table 8.1 Required BCP Syntax Arguments Continued . out of SQL Server. BCP is limited to working with flat files and SQL Server. If you want to get data from another data source (e.g., and Oracle database) into SQL Server, BCP is not the most. Data  Distributed Queries  SQL Server Integration Services  Alternative ETL Solutions  ETL Techniques Chapter 8 MCTS SQL Server 2008 Exam 432 314 Chapter8•ETLTechniques Introduction The ETL (extract/transform/loading). Server to another. The data must first be exported from one database to a flat file and then imported to the destination from the flat file. So let’s start with the basic structure of the BCP utility: bcp