Transcription of Displaying Data from Multiple Tables
{{id}} {{{paragraph}}}
Example: stock market
Displaying Data from Multiple Tables
Displaying data fromMultiple TablesChapter 41 ObjectivesAfter completing this lesson, you should be able to do the following: Write SELECT statements to accessdata from more than one table usingequality and nonequality joins View data that generally does not meet ajoin condition by using outer joins Join a table to itselfLesson AimThis lesson covers how to obtain data from more than one table , using the different methods Product A Cartesian product is formed when: A join condition is omitted A join condition is invalid All rows in the first table are joined to all rows in the second tableTo avoid a Cartesian product, always include a valid join condition in aWHERE a Cartesian ProductSELECT ename, dnameFROM emp, dept;ENAME DNAME BLAKE ACCOUNTING SMITH ACCOUNTING ALLEN ACCOUNTING 56 Rows Selected4 What Is a Join?Use a join to query data from more than one SyntaxWrite the join condition in the WHERE , table2. column2 FROM table1, table2 WHERE tablel.
Objectives After completing this lesson, you should be able to do the following: •Write SELECT statements to access data from more than one table using equality and nonequality joins
Loading..
Tags:
Information
Domain:
Source:
Link to this page:
Please notify us if you found a problem with this document: