Java™ How To Program (Early Objects), Tenth Edition

Selecting Data Subsets

Different users of a database are often interested in different data and different relationships among the data. Most users require only subsets of the rows and columns. Queries specify which subsets of the data to select from a table. You use SQL to define queries. For example, you might select data from the Employee table to create a result that shows where each department is located, presenting the data sorted in increasing order by department number. This result is shown in Fig. 24.2. SQL is discussed in Section 24.4.

Fig. 24.2 | Distinct Department and Location data from the Employees table.