How does jdbc connection work

Also, keep in mind that the placeholders are numbered, starting with 1. For the second one setString 2, someOtherString etc. Second, executing the query will return you a ResultSet , which is basically a list of all the rows that your database found for a given query. Note that the ResultSet offers different get methods, like getString or getInt or getDate , that you need to call depending on the column types of your returned database records. FirstName and LastName are string columns, so we simply call getString.

Inserting rows into the database is somewhat similar to selecting rows. Once more, you should use a PreparedStatement with? Updating rows is basically identical to inserting rows. You create a PreparedStatement and call executeUpdate on it. ExecuteUpdate will now return you the actual number of updated rows. Opening and closing database connections think: tcp sockets and connections like you did above with the DriverManager.

Especially in web applications, you do not want to open up a fresh database connection for every single user action, rather you want to have a small pool of connections that are always open and shared between users. Unfortunately, In Java land you are hammered with a plethora of options when it comes to connection pools:. HikariCP recommended. Independent of the option you choose, you will then, in your JDBC code, not open up connections yourself through the DriverManager, but rather you will construct a connection pool, represented by the DataSource interface, and ask it to give you one of its connections.

You need to create a connection pool data source somewhere in your application. Here, we extracted the creation code to another method. This is HikariCP specific configuration code. In the end, though, we simply set the same parameters we would have set on the DriverManager.

The first time we ask our HikariDataSource for a database connection, it will initialize a pool behind the scenes - which means opening up by default 10 database connections and giving you one of these ten. The java.

Connection interface defines the contract for relational database vendors. The vendor connection classes must implement these methods. An instance of Connection is used to communicate with the Database. The implementation of the Connection interface depends on the database vendor. The string argument is the fully classified name of the Connection implementation class. The DriverManager class uses service provider mechanism to search for jar files having a file named java.

This is a simple text file that contains the full name of the class that implements the java. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode.

Note When using the sqljdbc4. Note Calling the close method will also roll back any pending transactions. Is this page helpful? Yes No.