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Exercise #6 (tips and solutions)

Joining of tables (here inner join is needed) is possible to execute in two ways:

1. Through WHERE clause (a single opportunity before occurrence of standard SQL-92)

  1. SELECT DISTINCT Product.maker, Laptop.speed
  2. FROM Product, Laptop
  3. WHERE Product.model = Laptop.model
  4. AND Laptop.hd >= 10

2. By means of explicit operation of JOIN

  1. SELECT DISTINCT Product.maker,Laptop.speed
  2. FROM Product JOIN
  3. Laptop ON Product.model = Laptop.model
  4. WHERE Laptop.hd >= 10

Though  A database management system (DBMS) by Microsoft Corporation. SQL(Structured Query Language) is a database computer language designed for the retrieval and management of data in relational database management systems (RDBMS), database schema creation and modification, and database object access control management.SQL Server query optimizer will produce the identical plans of executing both queries, the second variant which allows to separate conditions of joining the tables from conditions of  filtering the rows is preferable.

To return to discussion of exercise #6

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