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Exercise #6 (tips and solutions)

There are two ways to perform a table join (in this case, an inner join is needed):

1. Using a WHERE clause (the only option before the SQL-92 standard has been introduced)

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

2. Explicit use of a JOIN statement

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

Although the  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 generate identical execution plans for both queries, the second alternative is preferable, since it allows to keep apart join conditions and row filtering criteria.

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