What is ETL in Sql ?

What is ETL: ETL stands for Extract, Transform, Load. Extract means to read data from source, Transform means to apply business logic on data & in last load means to add or load data on other server.

ETL (Extract, Transform and Load) is a process in data warehousing responsible for pulling data out of the source systems and placing it into a data warehouse. ETL involves the following tasks:

ETL (Extract, Transform and Load) is a process in data warehousing responsible for pulling data out of the source systems and placing it into a data warehouse. ETL involves the following tasks:

  • extracting the data from source systems (SAP, ERP, other operational systems), data from different source systems is converted into one consolidated data warehouse format which is ready for transformation processing.
  • transforming the data may involve the following tasks:
    applying business rules (so-called derivations, e.g., calculating new measures and dimensions),
    cleaning (e.g., mapping NULL to 0 or “Male” to “M” and “Female” to “F” etc.),
    filtering (e.g., selecting only certain columns to load),
    splitting a column into multiple columns and vice versa,
    joining together data from multiple sources (e.g., lookup, merge),
    transposing rows and columns,
    applying any kind of simple or complex data validation (e.g., if the first 3 columns in a row are empty then reject the row from processing).
  • loading the data into a data warehouse or data repository other reporting applications.

Why we need ETL ?: we need it because whenever you need to move some logic or data from one server to another server then you need to write ETL. for example: you have written a query i.e. using linked server or more than one database so it will take time to run so it’s better option to write ETL for particular data tables.

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About Hiren Kubavat

PHP Developer
This entry was posted in oracle, sql. Bookmark the permalink.

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