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To fix design problems with an existing legacy database schema. Database refactorings are often motivated by the desire for database normalization of an existing production database, typically to "clean up" the design of the database. To implement what would be a large (and potentially risky) change as a series of small, low-risk changes.
Read, retrieve, search, or view existing entries; Update, or edit existing entries; Delete, deactivate, or remove existing entries; Because these operations are so fundamental, they are often documented and described under one comprehensive heading such as "contact management" or "document management" in general. [citation needed]
Some data warehouses may overwrite existing information with cumulative information; updating extracted data is frequently done on a daily, weekly, or monthly basis. Other data warehouses (or even other parts of the same data warehouse) may add new data in a historical form at regular intervals – for example, hourly.
If the data is being persisted in a modern database then Change Data Capture is a simple matter of permissions. Two techniques are in common use: Tracking changes using database triggers; Reading the transaction log as, or shortly after, it is written. If the data is not in a modern database, CDC becomes a programming challenge.
A relational database management system uses SQL MERGE (also called upsert) statements to INSERT new records or UPDATE or DELETE existing records depending on whether condition matches. It was officially introduced in the SQL:2003 standard, and expanded [citation needed] in the SQL:2008 standard.
Data cleansing or data cleaning is the process of identifying and correcting (or removing) corrupt, inaccurate, or irrelevant records from a dataset, table, or database.It involves detecting incomplete, incorrect, or inaccurate parts of the data and then replacing, modifying, or deleting the affected data. [1]
An SQL UPDATE statement changes the data of one or more records in a table.Either all the rows can be updated, or a subset may be chosen using a condition.. The UPDATE statement has the following form: [1]
Data erasure (sometimes referred to as data clearing, data wiping, or data destruction) is a software-based method of data sanitization that aims to completely destroy all electronic data residing on a hard disk drive or other digital media by overwriting data onto all sectors of the device in an irreversible process. By overwriting the data on ...