SQL Templates
SQL templates are actually a favorite feature of mine that
likely should have made it into one of my other articles that highlight the top
features of the SQL Builder; however, I had to leave something of great
interest for this last section too!
IBM Data Studio supports the concept of templates.
Programmers are well familiar with these objects for extreme application
development. Essentially, templates are structured descriptions of coding
patterns that recur in source code. Java editors support the use of templates
to fill in commonly used source patterns. For example, a common coding pattern
is to iterate over the elements of an array using a FOR loop that indexes into the array. By using a template
for this pattern, you can avoid typing in the complete code for the loop.
Invoking Content Assist (Ctrl+Space) after typing a word will present
you with a list of possible templates for a FOR
loop in the Java perspective in IBM Data Studio. You subsequently choose the
appropriate template by name (in this case, Iterate over Array).
Selecting this template will insert the code into the editor and position your
cursor so that you can edit the details.
IBM Data Studio extends the benefits of templates for SQL
development as well, providing an enormous productivity boost for database
administrators (DBAs) and programmers alike. What’s more, since IBM Data Studio
can integrate with source control programs such as Microsoft Visual Source
Safe, IBM Rational ClearCase, Concurrent Versions System (CVS), and more,
you’ve got a great mechanism to ensure that best practices proliferate
throughout the organization and into your business logic.
As of the DB2 9.5 release, SQL Templates are only available
in the SQL Editor, so if you built your SQL statement using the SQL Builder,
open it using the SQL Editor to access this feature. You can access the
template list within the SQL Editor by invoking Content Assist (Ctrl+Space)
from within SQL Editor.
To see how this works, create a new SQL statement and press Ctrl+Space
below the default generated SELECT shell to see a list of all the available
built-in templates in IBM Data Studio. In the following example, you can see
that I selected the first occurrence of the XMLVALIDATE – XMLVALIDATE scalar
function template. (You select templates in the same manner that you select
Content Assist options.)
As you may have noticed, a lot of templates are already shipped
with IBM Data Studio. You can see all of the SQL-based templates that ship with
IBM Data Studio by selecting Windows>Preferences>SQL Editor>Templates.
IBM Data Studio also provides the ability to generate your
own SQL templates and subsequently retrieve them for use within the SQL Editor.
To create a new SQL template, perform the following steps in
the previous window:
1. Click
New. The New Template window opens.
2. Call
this template DescribeATable using the Name field.
3. Select
the type of statement you are creating using the Context drop-down list.
For this example, the default sql is fine. (If you were defining an
XQuery statement, you would select xquery instead.)
4. Leave
the Automatically insert field selected; this will instruct IBM Data
Studio to instantly add the template without prompting the SQL Editor after
you select it from the context pop-up menu.
5. Enter
a description of the template in the Description field.
6. Use
the Pattern field to enter the SQL statement. For our example, use the
following statement:
CALL ADMIN_CMD('describe select * from employee');
For this example, we want to create
a template SQL statement that will describe a table without having to use an
API or the command line processor (CLP). DB2 includes the ADMIN_CMD administrative routine that
effectively enables you to flow SQL to the database to subsequently perform management operations and so on. This make the management
of your data server via the SQL API much easier and broader scoped. Your New
Template window should now look like this:
You can use the Insert Variable button
to add special register variables into your SQL template as well. For example,
you could augment the previous template to include information such as the
current time when the statement was run, and so on:
7. Press
OK.
8. The
new SQL Template is added to the Templates window, as shown below. Click OK.
Once you’ve defined your custom template, you can refer to
it in the SQL Editor: simply type in the name of the SQL template and press Ctrl+Space.
IBM Data Studio will insert the template into the designer palette:
Note: You can also
type in the first few letters of the SQL template name and press Ctrl+Space,
and IBM Data Studio will insert the first SQL template it finds that
matches that combination. For our example, you could type DES, and then Ctrl+Space,
and IBM Data Studio would insert the DescribeATable SQL template you
created in the previous step.
From here, you use your editor as you normally would. For
example, run this SQL statement. In this example, you can see that the SQL
statement describes the EMPLOYEE table that resides in the SAMPLE database.
Now change employee to staff to describe that
table, and run the SQL statement again and you will see the structure of the
STAFF table.
Wrapping it up...
In this article, I rounded out
the features of the SQL Builder and finished off with a great feature that is
part of the SQL Editor -- SQL templates. The SQL Builder is good for single
data manipulation language (DML) statements, or to get you started. As you
noticed, in order to leverage SQL templates, you have to open an SQL statement
using the SQL Editor. (If you created your SQL statement using the SQL Builder,
you can still open it in the SQL Editor.) This seems like a great segue into
the next part of this series, where I will detail all the features of the SQL
Editor. By the time you are finished reading the next article, you’ll have an
excellent grasp of the SQL development features provided by IBM Data Studio,
and know which facility to use for the task at hand.
»
See All Articles by Columnist Paul C. Zikopoulos
Trademarks
IBM, DB2, ClearCase, and Rational
are trademarks or registered trademarks of International Business Machines
Corporation in the United States, other countries, or both.
Java and all Java-based
trademarks are trademarks of Sun Microsystems, Inc. in the United States, other
countries, or both.
Microsoft is a trademark of
Microsoft Corporation in the United States, other countries, or both.
Other company, product, or
service names may be trademarks or service marks of others.
Copyright International Business
Machines Corporation, 2008. All rights reserved.
Disclaimer
The opinions, solutions, and
advice in this article are from the author’s experiences and are not intended
to represent official communication from IBM or an endorsement of any products
listed within. Neither the author nor IBM is liable for any of the contents in
this article. The accuracy of the information in this article is based on the
author’s knowledge at the time of writing.
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