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2_Primary_key_presentation_l1_v2.pptx
Primary key
Questions
What is primary key?
Where do we use primary key?
What is a features of primary key?
Primary key
A primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records.
A primary key’s main features are:
It must contain a unique value for each row of data.
It cannot contain null values.
A primary key is either an existing table column or a column that is specifically generated by the database according to a defined sequence.
Video watching
https://www.youtube.com/watch?v=Py6F4vF5nno
What did you learn from the video?
Examples
Find 3 examples of primary keys we meet every day.
Thanks for the attention!
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