Tài liệu Công Nghệ Thông Tin

Cơ sở dữ liệu - Chapter 11: Stored procedures and triggers
Data type mapping Processing orientation SELECT USING for single row results Cursor for multiple row results Cursor is similar to a dynamic array Interface provides statements or procedures to declare, open, close, iterate (position), and retrieve values
48 trang | Chia sẻ: huyhoang44 | Ngày: 16/03/2020 | Lượt xem: 941 | Lượt tải: 0
Cơ sở dữ liệu - Chapter 10: Application development with views
Must rename columns: - derived columns - multiple columns with the same unqualified names (CourseNo from Offering and Course) Example 2: - Row summaries - Derived column: NumStudents - Must provide a name for all columns when one column is renamed - Positional notation for column names Access: - Use AS in the SELECT clause for de...
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Cơ sở dữ liệu - Chapter 9: Supplemental slides type ii nested query demonstration
Query execution: - For each Faculty row, execute nested query on the Student table - Faculty row does not qualify in the result unless it does not match any Student rows.
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Cơ sở dữ liệu - Chapter 9: Advanced query formulation with sql
Type I nested query with NOT IN condition One-sided outer join with IS NULL condition Difference operation using MINUS (EXCEPT) operator
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Cơ sở dữ liệu - Chapter 8: Physical database design
Minimize response time to access and change a database. Minimizing computing resources is a substitute measure for response time. Database resources Physical record transfers CPU operations Communication network usage (distributed processing)
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Cơ sở dữ liệu - Chapter 7: Normalization of relational tables
Insertion Insert more column data than desired Must know student number and offering number to insert a new course Update Change multiple rows to change one fact Must change two rows to change student class of student S1 Deletion Deleting a row causes other facts to disappear Deleting enrollment of student S2 in offering O3 causes loss of i...
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Cơ sở dữ liệu - Chapter 6: Developing data models for business databases
Identify entity types and attributes Determine primary keys Add relationships Determine connections Determine relationship cardinalities Simplify relationships
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Cơ sở dữ liệu - Chapter 5: Understanding entity relationship diagrams
Identification dependency M-N relationships with attributes Self identifying relationships M-way relationships Equivalence between M-N and 1-M relationships
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Cơ sở dữ liệu - SQL
The GROUP BY clause is used to group rows to compute group-statistics.  The syntax of GROUP BY command is: SELECT attribute name, aggregate function FROM table name GROUP BY attribute name;
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Cơ sở dữ liệu - Normalization for relational databases
Uses the concepts of FDs, primary key  Definitions: ◦ Prime attribute - attribute that is member of the primary key K ◦ Full functional dependency - a FD Y  Z where removal of any attribute from Y means the FD does not hold any more
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