- Good afternoon\n\n- We&#x2019;re going to take a quick look at the basic elements that make up JDBC\n
- Talk about exactly where JDBC fits into the Java language\n\n- Then look at some examples of the 4 basic CRUD operations for databases - Create, Read, Update and Delete\n\n
- Enterprise developer and architect\n\n- I work with these kinds of technologies on an almost daily basis\n\n\n- How about you? Anyone with JDBC experience? How about experience connecting to databases from other languages like .NET or PHP?\n\n\n
- This is a quick and shallow overview of JDBC so the pre-requisites are pretty light\n\n- Hopefully you know how to write and compile simple Java programs\n\n- Also, some knowledge of basic relationaly database concepts like tables and the SQL language\n
- In a nutshell, JDBC is simply an API that allows you to make a connection from a Java application to a relational database and execute SQL statements against that database\n\n- It is part of the core Java APIs and has been around since very early on in Java&#x2019;s life\n\n- All of the API is contained in 2 packages, java.sql contains the basic API, the javax.sql contains some more advanced API elements\n
- JDBC is the piece that sits between your code and the database\n\n- There is the standard API code, combined with a vendor specific Driver that knows how to talk to a particular database\n\n- In theory you can swap in a different driver and your program can work with a different database\n
- To initialize a Driver you simply use the standard Java classloader to load the Driver class\n\n- In this example we are loading a driver to talk to an Apache Derby database\n\n- In JavaSE 6, you don&#x2019;t even need to do this, it happens in the background as part of the new Service API\n\n
- url is a database specific string containing information on how to connect to the database, including credentials and other details\n\n- use the DriverManager to actually create the connection\n\n- notice the error handling\n
- pretty basic sql table create statement\n\n- notice that Derby doesn&#x2019;t support a boolean column type, so we use an integer, 0 for false, 1 for true\n\n- we have now introduced a little vendor dependency\n\n- use the connection to get a Statement object, and then execute the SQL\n
- once again, pretty standard SQL for inserting a row into a database\n\n- id column, name column, integer boolean column\n\n- once again we simply get a Statement object from our connection, then use it to run SQL against the database\n
- basic sql update statement\n\n- changing the value of the hired column to the value 1, and we use the where clause to specify which row we want to update\n\n- use the executeUpdate method call instead\n
- standard sql select statement, we want all columns from all rows\n\n- use the executeQuery method, which returns a ResultSet object\n\n- in this example we pass the result set to another method to print out the results\n
- so here is the printResults method, notice the ResultSet being passed into this method as a parameter\n\n- notice the while loop, this allows us to process each row in the result set in turn\n\n- notice the resultSet.get methods, which include a 1-based column index\n\n- if we run this code, can anyone tell me what actually gets printed to the screen?\n
- notice the true value for the first row, even though the value in the database was the number 1, the JDBC API was able to convert that to a boolean for us\n
- Of course once you have been inserting and updating data for a while, you inevitably need to delete some data\n\n- Notice the standard SQL delete statement, where we are saying to delete all rows in the candidates table whose id column has the value 888 in it\n\n- Get the Statement object from the connection and use it to run the SQL\n
Transcript of "JDBC Basics (In 20 Minutes Flat)"
JDBC Basics (In 20 Minutes Flat) Craig S. Dickson!
Agenda • What is JDBC? • Connecting to a database • Creating & Updating data • Querying data • Deleting data!
About Me • Software Architect, currently consulting with Adobe and BET • 15 years software development experience • Sun Certified JavaEE Architect!
Assumptions • Basic understanding of JavaSE 6 • Basic understanding of relational database concepts and SQL!
What is JDBC? • JDBC = Java Database Connectivity • Provides basic API for connecting to relational databases • Part of JavaSE since version 1.1 (c. 1997) • java.sql and javax.sql!
In conclusion ... • JDBC can be used to connect to relational databases from Java programs • Allows all basic CRUD operations and can handle sophisticated multi-tier, multi-vendor environments • Copious amounts of error handling required • Can unintentionally create a dependency to a specific database vendor!