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Posted Feb 19, 2008

DB2 9.5 and IBM Data Studio: Part 7: The SQL Builder's Development Accelerators

By Paul Zikopoulos

So far in this series about the IBM Data Studio Developer integrated development environment (IDE) that’s available with DB2 Version 9.5 (DB2 9.5), I’ve shown you how to set up database connection objects and the actions that you can perform on them. In addition, I introduced you (in Part 2) to some of the features available in the Database Explorer view, and Part 3 and Part 4 gave you a full tour of overview diagrams. In Part 5, you learned how to point-and-click your way to OLE DB functions that can integrate data from external data sources that have an OLE DB provider. In Part 6, I showed you how easy it is to create an SQL statement using the IBM Data Studio SQL Builder. In this installment, I’m going to show you my four favorite features in the SQL Builder that make this tool even more helpful than just point and clicking your way to an SQL statement like I showed you in the last article.

Things you have to do to follow the examples in this article...

I recommend that you start with Part 1 because I tend to build on the concepts and objects created in these series sequentially. For this article, I assume that you’ve at least created the SAMPLE database (use the db2sampl –xml –sql command) and that the FEMALEPERSONNEL SQL statement built in Part 6 resides in the SQL Scripts folder in a database development project. Your Data Project Explorer and Database Explorer views should look similar to these:

IBM Data Studio Query Builder productivity boosters

In this section, I’ll talk about my favorite features that really help boost productivity when you’re designing SQL statements using the Query Builder. I may have mentioned some of the features in past articles in this series, but this section will serve as a place where they can all come together.

SQL Assist

Perhaps one of the most rapid application development features that I know of in IBM Data Studio is SQL Assist. If you’ve ever worked with Microsoft Visual Studio and are familiar with IntelliSense, then you already have a good idea what I’m talking about. However, when you use the SQL Builder in IBM Data Studio, the assistance is hooked into the underlying database’s schema – not just the respective programming language semantics. In fact, since IBM Data Studio can maintain a cache of the data servers you are working with, you can even work in a disconnected mode (offline) and still leverage this feature. SQL Assist is a key part of the pureQuery initiative: it places the same assistance feature that Java programmers expect from their tools into an integrated editor that understands both Java and SQL.

For example, create a new query (call it FEMALEPERSONNEL2) and drag the DEPARTMENT and EMPLOYEE tables to your SQL Builder design canvas in the same manner you did in Part 6. IBM Data Studio should now look like this:

In the last article, you added columns to the query by simply selecting them from the middle pane of the SQL Builder. While you can use the graphical controls at the bottom of the SQL Builder to add clauses to your SQL statement, most developers are likely to use a combination of manual entry and assisted entry (like the Add Join and projection options I covered in Part 6). While the check box column definition method is more useful for those not as adept in writing SQL, even SQL maestros will want to use contextual assistance while they are writing the SQL statement; the SQL Builder offers this with SQL Assist.

In the area of the SQL Builder that displays the actual text of your SQL statement, try to manually append the following condition (shown in bold text below) to the SQL statement that was automatically generated for you:

 SELECT * FROM DEPARTMENT, EMPLOYEE 
 
 WHERE PAULZ.EMPLOYEE.WORKDEPT=’A00’ AND SEX=’F’ 
 
 ORDERBY PAULZ.EMLOYEE.LASTNAME

Note: Don’t forget to substitute the schema qualifier PAULZ used in this article for the schema you used to create the SAMPLE database. (On a Windows platform, it’s whatever user account you were logged in with when you ran the DB2 CREATE DATABASE command or db2sampl.)

Now I want you to erase the newly typed text and retype it pausing ever so slightly after you specify PAULZ - of course, replace PAULZ with your schema name. (Stop at the period.) In IBM Data Studio, when a period (.) follows a schema name that DB2 recognizes, the SQL Assist feature is automatically engaged and all the applicable objects in context (in this case, the schema objects) are automatically presented in a pop-up list for you, as shown below:

Simply select the object you are looking for from the pop-up list and press Enter. In this example, select the EMPLOYEE table and briefly pause after typing the qualifying period after the EMPLOYEE table name. You can see that SQL Assist is smart enough to recognize the context of the SQL statement: notice below that the pop-up list only shows the columns that are part of the EMPLOYEE table:

If you’re following along in this example, you’ll want to select the WORKDEPT column. Sometimes you may notice that the column you want isn’t on the pop up list. Obviously, you can use the scroll bar or your cursor movement keys to scroll down the list of returned columns - but there’s a better way! SQL Assist has filter and stemming options that quickly move focus in the pop-up list to the location based on the first key you press. In this example, if you pressed W, then the SQL Assist pop-up list would only display those columns that begin with this letter:

Note: You can also invoke SQL Assist by right-clicking in your SQL statement window and selecting SQL Assist from the pop-up menu, or by pressing Ctrl+Space after specifying an object name in your SQL statement.

Continue building this SQL statement, but now I want you to manually enter the AND SEX=‘F’ restriction. (Notice that it changed color - we’ll talk about that in a bit.) You can see that sometimes it’s better just to type something quickly than to leverage SQL Assist. As you get more accustomed to this great feature, you’ll decide for yourself when to use it and when to use your old fashioned fast-typing fingers. In this case, I know I don’t actually have to specify the schema here, and I know there is a column called SEX, and I know the value and its corresponding data type, so it was just faster to enter it myself.

Enter a space after SEX=‘F’. SQL Assist can help further, but it’s only going to show up if you ask for it using one of the methods detailed in the previous note (because there is no period triggering the action). For example, to add the ORDER BY clause, invoke SQL Assist and manually scroll the entire list of options to find this operator. (Of course, pressing a letter key will automatically move focus in the list to the first occurrence for that group):

You can see this list is very long. The point is that there is always some help available for you, and depending on the context of the SQL statement, it changes dynamically. Finish building this SQL statement and save your work.

Of course, since views and nicknames are presented like tables to applications, IBM Data Studio will link the SQL Assist features to enumerate all the qualifying views and nicknames, along with tables, in the list returned to the developer.

Another reason why this feature is so important is that if you were to create an SQL statement using the SQL Editor, you wouldn’t have the option to drag (or add) tables to the middle pane of the editor. You would just have the SQL text.

You can also customize the way SQL Assist behaves in IBM Data Studio. For example, you could choose whether to display SQL proposals (keywords, templates, and names of database objects) when you use content assistance while writing or editing an SQL statement. As previously mentioned, Ctrl+Space is the default key combination for this content assistance. If you want to change this combination, select Window>Preferences>General>Keys and change the configuration for Content Assist.

SQL Assist really enhances productivity because it moves the requirement away from knowledge of the database schema for productivity and places automated discovery of the schema in the hands of the application developers for a rapid application development experience: this is true extreme application development.



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