Primary Key

In the relational model of database design, a unique key or primary key is a set of attributes whose values uniquely define the characteristics of each row. The primary key has to consist of characteristics that cannot collectively be duplicated by any other row. In an entity relationship diagram of a data model, one or more unique keys may be declared for each data entity. Each unique key is composed from one or more data attributes of that data entity. The set of unique keys declared for a data entity is often referred to as the candidate keys for that data entity. From the set of candidate keys, a single unique key is selected and declared the primary key for that data entity.
Posts about Primary Key
  • Facebook Beefs Up Its App Install Ads for the Holiday Shopping Season

    …, build a custom audience using the top 25 percent of users. Then build a lookalike audience based off of it to find people with similar characteristics. Test multiple ad creatives, including video: As new mobile devices are activated over the holidays, this is the perfect time to test new ad creatives. Test five to 10 new concepts to improve overall campaign delivery and achieve campaign goals. Developers: What are your initial thoughts on these announcements? …

    David Cohen/ AllFacebookin Social- 21 readers -
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