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Relational Database Concepts 22-May-17 db.ppt relational database example •contain tables •tables contain records (rows) •records are broken into columns (fields) 22-May-17 PK_ID Quote FK_Sources 1 I don’t like that man; I must get to know him better. 4 2 I wish I had an answer to that because I'm tired of answering that question. 1 3 Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. 3 4 People are just as happy as they make up their minds to be. 4 db.ppt first design for the MyQuotes database Quotes table: PK_ID 22-May-17 QuoteBody 1 I don’t like that man; I must get to know him better. 2 I wish I had an answer to that because I'm tired of answering that question. QuoteSource Abraham Lincoln Yogi Berra 3 Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. William Penn 4 People are just as happy as they make up their minds to be. Abe Lincoln db.ppt •Are records 1 and 4 from the same source? a better design for the MyQuotes database Quotes1 table: PK_ID 1 Quote FK_Sources I don’t like that man; I must get to know him better. 4 2 I wish I had an answer to that because I'm tired of answering that question. 1 3 Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. 3 4 People are just as happy as they make up their minds to be. 4 Sources1 table: PK_SourceID Source 1 Yogi Berra 2 Mark Twain 3 William Penn 4 Abraham Lincoln SELECT Quotes1.QuoteBody, Quotes1.FK_SourceID, Sources1.PK_SourceID, Sources1.SourceBody FROM Quotes1, Sources1 WHERE Quotes1.FK_SourceID=Sources1.PK_SourceID 22-May-17 db.ppt “inner join” SQL statement SELECT Quotes1.QuoteBody, Quotes1.FK_SourceID, Sources1.PK_SourceID, Sources1.SourceBody FROM Quotes1, Sources1 WHERE Quotes1.FK_SourceID=Sources1.PK_SourceID theAnswer = myResultSet.getString(1) + " " + myResultSet.getString(4); “join” because it gets data from two different tables “inner” because each table only returns matching records 22-May-17 db.ppt tables represent “relationships” • one to one relationship (1 table) • a table of Persons may directly contain the social security number • one to many relationship (2 tables) • a table of Sources • a table of Quotes • each Quotes record points to one Sources record • many to many relationship (3 tables) • a table of Persons • a table of Skills • a table of Person-Skills • for each skill that a person has, there is a record here • for each person that has a skill, there is a record here 22-May-17 db.ppt Relational Database Concepts • • • • Relationships Contraints Triggers Stored procedures • Tables • Views • Indexes • Keys • • • • Rows (Records) Columns (Fields) Clustered indexes Non-clustered indexes • Primary keys • Foreign keys • Composite keys • Locking • Isolation Levels (for transactions) 22-May-17 • • • optimistic pessimistic gets complicated! db.ppt the end of this PowerPoint file Hooray! 22-May-17 db.ppt