IT163 Unit 5 BD - Research Paper Example

Join query Number: Lecturer: This paper will analyze a join query. This is an example of a data manipulation ment. This is in the sense that the data that is stored in the database is manipulated to get the required information. A join query is a SQL statement that is used for the retrieval of information from more than one table or views. There are two differences between join query and normal query. In a join query, the FROM clause is used to refer to more than two tables or views in a database.

Another difference is that there is a condition that is specified in the join query which is referred to a join condition. The join condition brings the relationship between the rows of one table and the rows of another table. The join query enables a query to select any number of columns from more than two tables (Connolly, & Begg, 2005). If two of these tables have a column which share the same name, then all the qualifying name attributes of the columns will be used so that the queries will have the name of the table that is used.

Join query come in many flavors according to the location where the join query will be located. There are conditions that join query will work. A join query will either work under WHERE clause or FROM clause. These are the conditions that will enable join queries to work. This is in aimportant aspect which should be looked into when undertaking and creating join queries. In an example where there are two tables holding persons information and the order information, if one wants to get some data from the two tables (Connolly, & Begg, 2005).

SELECT Persons.LastName, Persons.FirstName, Orders.OrderNoFROM PersonsJOIN OrdersON Persons.P_Id=Orders.P_IdORDER BY Persons.LastNameReferencesConnolly, M., & Begg, C. (2005). Database systems: A practical approach. CA: Addison-Wesley.