Beginning Oracle Database 11g Administration From Novice to Professional

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CHAPTER 2 SQL AND PL/SQL
Introduction to PL/SQL
Oracle gives us the ability to store programs in the database—and these programs are
often written by using a proprietary Oracle language called Procedural Language/SQL, or
PL/SQL. PL/SQL offers the entire suite of structured programming mechanisms such as
condition checking, loops, and subroutines. Of course, just like programs written in other
languages, PL/SQL programs communicate with Oracle by using SQL.
Here is an example of a PL/SQL program to delete a supplier record and any associated
quote records—first a flow chart in Figure 2-5, and then the actual program itself in
Listing 2-21. 6
PROCEDURE delete_supplier
(suppliername_in IN VARCHAR)
DELETE FROM supplier
WHERE suppliername =
suppliername_in;
Yes
ROWCOUNT > 0 ?
No
No
Error?
Yes
No
SQLCODE = -2292?
Child records were found.
Delete those first.
Yes
Display success
message
Display error
message
Display error
message
DELETE FROM quote
WHERE suppliername =
suppliername_in;
Yes
Error?
No
Now try
deleting the
parent again.
Display error
message
DELETE FROM supplier
WHERE suppliername =
suppliername_in;
Yes
Error?
No
End
Display error
message
Display success
message
Figure 2-5. Flow chart for the procedure
6. If the and tables are related by referential constraints and the
option is included in the definition of the table, Oracle will automatically delete a record
when the corresponding record is deleted. For the purposes of this example, we assume that
this option has not been used.