Using inner join, PL-SQL Programming

Using INNER JOIN

INNER JOIN is used to retrieve the data from all tables listed based on a condition of equality listed after keyword ON. If the condition is not meet, rows are not returned. For example, see the following tables in our classicmodels sample database. We have employees table and offices table. Two tables are linked together through the keyed column officeCode. OfficeCode is the primary key of the offices table and is a foreign key in the employees table. To find out what employees work in which countries and states we can use INNER JOIN to join the offices and employees table. We return columns from both tables (note the fully qualified column names like "employees.firstname"), but only the rows where the officeCode in each of the tables match. Here is the SQL code:

SELECT employees.firstname,

employees.lastname,

offices.country,

offices.state

FROM employees INNER JOIN offices

  ON offices.officeCode = employees.officeCode

And we will get the data like this:

+-----------+-----------+-----------+------------+

| firstname | lastname  | country   | state      |

+-----------+-----------+-----------+------------+

| Diane     | Murphy    | USA       | CA         |

| Mary      | Patterson | USA       | CA         |

| Jeff      | Firrelli  | USA       | CA         |

| William   | Patterson | Australia | NULL       |

| Gerard    | Bondur    | France    | NULL       |

| Anthony   | Bow       | USA       | CA         |

| Leslie    | Jennings  | USA       | CA         |

| Leslie    | Thompson  | USA       | CA         |

| Julie     | Firrelli  | USA       | MA         |

| Steve     | Patterson | USA       | MA         |

| FoonYue  | Tseng     | USA       | NY         |

| George    | Vanauf    | USA       | NY         |

| Loui      | Bondur    | France    | NULL       |

| Gerard    | Hernandez | France    | NULL       |

| Pamela    | Castillo  | France    | NULL       |

| Larry     | Bott      | UK        | NULL       |

| Barry     | Jones     | UK        | NULL       |

| Andy      | Fixter    | Australia | NULL       |

| Peter     | Marsh     | Australia | NULL       |

| Tom       | King      | Australia | NULL       |

| Mami      | Nishi     | Japan     | Chiyoda-Ku |

| Yoshimi   | Kato      | Japan     | Chiyoda-Ku |

| Martin    | Gerard    | France    | NULL       |

+-----------+-----------+-----------+------------+

23 rows in set (0.02 sec)

We could make the above query return more specific results. What if we want to find only employees in USA? The following query adds an AND clause to narrow down the country:

SELECT e.firstname,

e.lastname,

state

FROM employees e INNER JOIN offices o

  ON o.officeCode = e.officeCode

WHERE  country = 'USA' ;

Here is the resulting data

+-----------+-----------+-------+

| firstname | lastname  | state |

+-----------+-----------+-------+

| Diane     | Murphy    | CA    |

| Mary      | Patterson | CA    |

| Jeff      | Firrelli  | CA    |

| Anthony   | Bow       | CA    |

| Leslie    | Jennings  | CA    |

| Leslie    | Thompson  | CA    |

| Julie     | Firrelli  | MA    |

| Steve     | Patterson | MA    |

| FoonYue  | Tseng     | NY    |

| George    | Vanauf    | NY    |

+-----------+-----------+-------+

10 rows in set (0.00 sec)

Posted Date: 2/16/2013 8:21:32 AM | Location : United States







Related Discussions:- Using inner join, Assignment Help, Ask Question on Using inner join, Get Answer, Expert's Help, Using inner join Discussions

Write discussion on Using inner join
Your posts are moderated
Related Questions
SQL Database: So, an SQL database is one whose symbols are organized into a collection of tables. Now, shows an SQL table as the current value of an SQL variable, ENROLMENT, b

Enrolment was split - SQL Example shows how relvars IS_CALLED and IS_ENROLLED_ON can be derived from the original ENROLMENT relvar, using projection in the initial assignment

GOTO Statement The GOTO statement branches to a label unconditionally. The label must be exclusive within its scope and should precede an executable statement or a PL/SQL block.

Data Types in SQL - Integer INTEGER or  synonymously INT, for integers within a certain range. SQL additionally has types SMALLINT and BIGINT for certain ranges of integers. T

Data Types in SQL - Interval, Boolean INTERVAL for values denoting, not intervals (!) but durations in time, such as 5 years, 3 days, 2 minutes, and so on. BOOLEAN, con

Define basic operators of relational algebra with an example each


Iteration Schemes The bounds of a loop range can be variables, literals, variables, or expressions but must compute to integers. Below are some of the examples. As you can see t

SQL Cursor   The Oracle implicitly opens a cursor to process each SQL statement not related with an explicit cursor. The PL/SQL refers to the most current implicit cursor as t

Great Plains (Microsoft Dynamics) Purchases Report Project Description: I want to build a purchases report that matches the General Ledger. presently, when I join the PM20