ACCT 484 Lecture Notes - Lecture 14: Relational Database, Information Retrieval, Data Model
26 Sep 2016
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Two assignments, queries are in your textbook page 134/206. Write the complete queries not what the book is asking for. Most basic cartesian (cross)product compares every row of one relation to every row of the other relation looking for matches. Example join two tables with three rows each i. e. 3 salesperson records and 3 customer records. Avoid if at all possible: join operation. Inner join returns only qualifying results from the joined tables. List names of salespersons and customers: inner join operation two syntaxes. On (salesperson. spnum = customer. spnum): system defaults to inner join if you don"t put inner or outer join, join operation. Outer join returns qualifying results from one table and all rows from the other (outer) table: results (if we add slow hawk as a salesperson) Chapter 1 a data miner look at sql: sql, big data, relational databases. Picturing the structure of data: data model, table. Restrictions and can do inner join simple syntax: group by.
