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Structured Query Language (SQL)

This guide provides a comprehensive overview of Structured Query Language (SQL) commands for creating tables and managing relations within a database. It covers the syntax for creating tables with attributes, including defining primary and foreign keys, as well as formulating SQL queries to retrieve specific data. Practical examples include requesting names of department managers from employee and department relations, filtering results using WHERE clauses, and utilizing GROUP BY for data aggregation. Enhance your database management skills with essential SQL techniques, including triggers for monitoring changes.

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Structured Query Language (SQL)

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  1. Structured Query Language(SQL)

  2. BOOK RELATION

  3. CREATE TABLE SYNTAX CREATE TABLE <RELATION NAME> ( <ATTRIBUTE> <TYPE> [NOT NULL], <ATTRIBUTE> <TYPE> [NOT NULL], ... CONSTRAINT PRIMARY KEY (<ATTRIBUTE(S)>) [,] [FOREIGN KEY (<ATTRIBUTE(S)>) REFERENCES <RELATION> (<ATTRIBUTE(S)>)] [,] [FOREIGN KEY (<ATTRIBUTE(S)>) REFERENCES <RELATION> (<ATTRIBUTE(S)>)] ... )

  4. SUPPLY DATABASE

  5. EMPLOYEE & DEPARTMENT RELATIONS EMPLOYEE DEPARTMENT

  6. SQL FOR GET NAMES OF DEPARMENT MANAGERS SELECT NAME FROM EMPLOYEE, DEPARTMENT WHERE EMPLOYEE.SSN = DEPARTMENT.MGRSSN

  7. CARTESIAN PRODUCT OF FROM CLAUSE

  8. CARTESIAN PRODUCT FILTERED BY WHERE CLAUSE

  9. PROJECT DOWN TO ATTRIBUTES IN SELECT CLAUSE

  10. People The PEOPLE Relation

  11. Result SELECT Name, Age FROM People WHERE Dependents = 0 ORDER BY Age DESC, Name ASC Ordering Query Results

  12. People SELECT Age, COUNT(*) FROM People GROUP BY Age The PEOPLE Relation Partitioned Into Groups

  13. Intermediary table for LEFT OUTER JOIN QUERY: SELECT SNAME, P# FROM S, (SELECT * FROM SPJ WHERE J#=‘J1’) SPJ1 WHERE S.S#=SPJ.S# (+)

  14. TRIGGERS: LEDGER and LEDGER_AUDIT TABLES LEDGER LEDGER_AUDIT

  15. TRIGGERS: EXAMPLE create trigger ledger_update before update on LEDGER for each row when ((new.Amount/old.Amount)>1.1) begin insert into LEDGER_AUDIT values (:old.ActionDate, :old.Action, :old.Item, :old.Quantity, :old.QuantityType, :old.Cost, :old.Total, :old.Person); end;

  16. TRIGGERS: SYNTAX

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