#Postgresql having install#
#Postgresql having driver#
#Postgresql having code#

I could also read the resulting rows into a list, all at once, using a call to sql.rows(), which can transform the data in a manner similar to using.I could have accomplished this similarly to the Java version for example, instead of calling sql.eachRow(), I could have called sql.query(), which takes a closure as its last argument and passes a result set to that closure, at which point I would have probably used a while() as in the Java version (or maybe each()).Groovy can simplify your lifeįor those of you whose day job involves scripting and relational databases, I think it's pretty obvious from the above that Groovy can simplify your life. The eachRow() method takes a closure as its final argument and passes each row to the closure as it processes the returned lines of data from the table. Line 7 calls the eachRow() method of the Sql instance, wrapping the creation and processing of the result set. Closes the instance of Sql when the closure exits.Takes a closure as its final parameter, passing it the instance of Sql that it created.Creates an instance of Sql (connection, statement, etc.).The method call is Sql.withInstance(), similar to other uses of 'with' in Groovy.

Line 6 is doing a bunch of heavy lifting.

#Postgresql having driver#

The first three are the same as for the fourth names the driver I want. Lines 2-5 define the four strings needed to connect to a database using the Sql class. In my view, not having to jump around JavaDocs for three different classes is a distinct advantage. Okay, that's a lot shorter–10 lines instead of 24! Here are the details:

#Postgresql having code#

Here's the Java code to look at the land cover data I loaded in the second article linked above: 1 import ħ public static void main(String args) ' Groovy, as usual, streamlines the process.

In Java, the correspondence between the code and the list above is essentially one-for-one.

Close the Statement and Connection instances when done.

Process the ResultSet instance returned by having the Statement instance execute the query, for example, printing the rows returned on the console.

Using an SQL string, get an instance of a Statement (or something similar, like a PreparedStatement) that will handle the execution of the SQL string.

Establish a Connection instance to the database back end where the data resides.

Whether you're using Java or Groovy, several basic steps happen in any program that uses JDBC to pull data out of a database: If you haven't already, please review this article on installing JDBC and this article on setting up PostgreSQL.

Java version 11.0.12-open of OpenJDK 11.

For this article, I'm using SDK's releases of: A nice alternative for Linux users is SDKMan, which provides multiple versions of Java, Groovy, and many other related tools.

#Postgresql having install#

Both a recent/decent version of Java and Groovy might be in your Linux distribution's repositories, or you can install Groovy by following these instructions. Groovy is based on Java and requires a Java installation. This article examines some differences between connecting to a PostgreSQL database using JDBC in Java versus Groovy. Lately, I've been looking at how Groovy streamlines the slight clunkiness of Java.