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Primary key &  Foreign key 

Primary key &  Foreign key . By: Afra`a Sayah. Primary key & Foreign key. Primary key: It`s uniquely identifies each record in the table. A primary key contains a single column or a set of columns . Foreign key:

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Primary key &  Foreign key 

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  1. Primary key &  Foreign key  7-3d By: Afra`aSayah

  2. Primary key & Foreign key Primary key: • It`s uniquely identifies each record in the table. A primary key contains a single column or a set of columns. Foreign key: • Is a column, or groupingof columns, that contain values that are found in the primary key of some table . A foreign key almost always is not unique. 7-3d

  3. Example 1 7-3d

  4. Example 1 7-3d

  5. Example 1 7-3d

  6. Example 2 7-3d

  7. Example 2 7-3d

  8. Example 3 7-3d

  9. 7-3d 7-3d 8-9

  10. Primary Key Featured • Primary Key is always unique • Primary Key never repeated or kept null • Primary Key can be on one column or many columns together. 7-3d

  11. Thank you 7-3d

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