Week 6 – CST– 363
Introduction to Database Systems
Summarize
what you have learned this week.
This week, I have learned how to design a database ERD
more efficiently. The relationship lines can be used to show the type of
relationship two entities share. The dotted lines indicate non-identifying relationships,
and the solid lines indicate identifying relationships. In a non-identifying relationship,
the child entity has a foreign key from the parent, but it does not make up the
child’s primary key. In an identifying relationship, the foreign key is part of
the primary key. In a good design, you want to keep primary keys minimal without
unnecessary columns.
This week we are learning how to code a web application
that uses a database. We are using JDBC which stands for Java Database
Connectivity. We are using Connector/J which is the official JDBC driver for MySQL.
In order to use the database, you must first create a
connection using the DriverManager.getConnection() method. You must specify a
database server address, a database name, login username, and password.
Connections are created in a try-block of a try-catch statement because the connection
will fail if the database is not found, or the login credentials are invalid.
I also learned about the SQL Injection Attack. This is
an attack that can happen when a “clever user” enters a sequence of characters
like 0’ or ‘1’=’1 into a query that is constructed using string concatenation. This
results in a select statement like Select * from instructor where name = ‘0’ or
‘1’ = ‘1’, which returns all rows from the table. Using a prepared statement
prevents SQL injection when assigning values to placeholders.
Comments
Post a Comment