Notes for CS 348 Exam - Summary Databases PDF

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Professor was Walid Ahmed...

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Notes for CS 348 Exam University Example 1. Sid, cid, grade 2. Sid is key - Student can take at most one course 3. Cid is key - Course can be taken by at most one student 4. Cid, grade is key - For a given course, no two students can have the same grade 5. Sid, grade is key - A student can get the same grade 6. Grade is key - only one grade can be given in the entire university 7. Sid, cid, grade - A student can take the same course as long as the student does not get the same grade. SQL Turing complete- It is not equivalent to a Turing Machine. But PL/SQL is a Turing Complete. JDBC is Turing Complete. Data Definition Language: (SQL Example Create Table) Data Manipulation Language: (Insert/Delete/Select tuple) Levels of Data Management: ○ User Interface ○ Query Parser ○ Query Optimizer ○ Query Processor ○ Axis/Table Manager: How to access an attribute in a table ○ Memory and Buffer Manager ○ Disk management is the core of the Database Management. ■ Note: Management, Security and Concurrency manager is available across all the levels Integrity Constraints: To make sure the data is integral, consistent and remains valid. ○ Account balance not negative. ○ Attribute not being null ○ Phone Number being a null (Domain Constraints). ○ Unique Key/Foreign (Referential Integrity Constraints or Foreign Key Constraints) Mathematical Foundation of SQL: ○ Relational Algebra ○ Relational Calculus ○ Query By Example (QBE): Builds on Domain Relational Calculus. They are declarative. ○ SQL: Builds on Tuple Related Calculus. They are declarative. Entity Relationship Model: ○ Entity ○ Relationships ○ Attributes of the Relationship ○ The Arity of the Relationship (one to one, one to many and so on) ○ Key Constraints Note: Given schema and constraints and check whether a tuple violates constraints Note: May give two SQL Queries and ask whether they return the same values. Note: May give a sentence and ask to translate into SQL.

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Note: May give scheme and a SELECT query and ask what the query will do....