Database Reference
In-Depth Information
•
You can define queries involving the use of set operators —
UNION, UNION ALL, INTERSECT, and MINUS.
•
You can define queries that make use of execution-time variables.
•
You can define queries that make use of various SQL*Plus format
commands.
•
Typically, software applications do not use SQL only, but embed
SQL statements in programs written in another HLL.
•
A dynamic query is a query that uses data fed to it to construct
a
Select
statement that is then executed. It avoids hard-coding
values, thereby providing more flexibility to the end uses that use it.
Complete discussion of all aspects of the
Select
statement could easily take up a
considerable portion of a book. The chapter captures and discusses the salient features,
which if mastered, will place you on a solid footing in any environment that requires
expertise in SQL.
One thing that should be clear is the remarkable power of the language. This can be
appreciated if you attempt to write a Java or C++ program to replace any of the examples
provided in the chapter. No wonder it is the universal database language. But go on to the
next chapter, as there is much more to learn about the language.
12.17 Review Questions
1.
Describe three ways in which data may be inserted into base
table.
2.
Write PL/SQL blocks to allow you to quickly populate the
sample college database (created in Chapter 11) with data.
Test these out in Oracle.
3.
Write PL/SQL blocks to allow you to quickly modify data in
your database. Test these out in Oracle.
4.
Write PL/SQL blocks to allow you to easily delete data from
your database. Test these out in Oracle.
5.
Explain the purpose of the
Commit
and
Rollback
statements.
Demonstrate how they may be used.
6.
Practice writing the following:
•
Simple queries
•
Queries Involving Multiple Tables
•
Queries Involving the Use of Functions
•
Queries Using LIKE, BETWEEN and IN Operators
•
Nested Queries
