Difference between Schema and Instance
Schema: Overall structure of a database is called database schema. Schema of a database is represented as a diagram relationships between the tables is expressed by schema. Stored data in that table are not represented by schema. So, the overall skeleton infrastructure of the database is considered as database schema.
Instance: The data which is stored in the database at specific time is called instance of database. DBMS can changes a lot of time rapidly. So the information inserted, manipulated and deleted in particulars time need to be stored and instance is used for that purpose.
| Schema | Instance |
|---|---|
| 1. Overall structure of a database. | 1. Data which is stored in a database at specifie time. |
| 2. Does not change with time. | 2. Changes frequently with time. |
| 3. Data or information cannot be hold by database schema. | 3. In DBMS, information are changed with time and instance store all the information. |
| 4. Entities and relationships among entities are defined by schema. | 4. Instance is considered as a snapshot of the database. |
| 5. In schema, primary state is empty. | 5. In instance, primary state may always have some information. |
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Contributed By: Romana Rahman Ema