The basics: editing, deleting, disconnecting, and refreshing connections
You can perform a number of basic operations from a live
database connection so I decided to lump them all together in this one section.
The Edit Connection option
You can edit a database connection whether its object is
connected or not. When you select Edit Connection, the Edit Connection
window opens:
You may want to edit a database connection for several
reasons, such as to use a different user account that has different privileges
on the data server, or to modify a filter created on the original database
connection object. I’m not going to detail all the things you can do with this
option because they are very similar to those available when adding a new
database connection, which were outlined in Part 1 of this series.
Tip: If you frequently work with different
user IDs or focus on different schemas, I recommend that, instead of editing
the database connection object, you simply create multiple connections to the
same database with different credentials or schema filters. For example, in the
following figure, you can see that I have multiple database connection objects that are
bound to the SAMPLE database. One of the connections has a filter that applies
a PAULZ-only schema filter and another object doesn’t have any filter at all
yet both use the same user account to connect to the data server. A third database
connection object uses a different user account (SECADM) to connect to the database:
The Delete option
The Delete option in this context only
deletes the database connection object not the database itself. (I can hear
the sighs of relief already.) The only other thing I’ll mention about this
option is that you don’t get a confirmation dialog box when you select it (at
least in the beta version) – so ensure that this is what you want to do.
The Disconnect option
As you might expect, you use this option to disconnect a
database connection object from the database for which it was created. Note
that the disconnection happens only on the selected database connection object.
For example, if you had two database connection objects with live connections
to the same database, disconnecting one object will not affect the other, as
shown below:
Note: The Disconnect option’s icon can
be a bit misleading because it’s the same as the disconnected server icon. The
purpose of the icon is to represent the final state, but because of its color,
it may appear as if it’s not an available option.
The Refresh option
As you change things in the Database Explorer view, those
changes aren’t always immediately reflected in this view. Several reasons for
the delay are possible: you are working in offline mode, the cache hasn’t been
updated, and so on. If you ever create an object and it doesn’t show up, or
connect to a database and the status still shows disconnected, select the Refresh
option. (If you’ve ever worked with the Windows Explorer in Microsoft Windows
then you’re already familiar with this ‘clean-up’ task; it’s the same concept
here).
Add to Overview Diagram
When you are connected to a database, you can add the
database object to an overview diagram. Overview diagrams
automatically include all or a selected set of data objects. If you build overview
diagrams using the Information Engineering (IE) or Unified Modeling Language
(UML) notation, you can discover and draw implicit foreign key relationships
between these objects. I find that overview diagrams help me to understand the interaction
between data objects.
When you select the Add to Overview Diagram option,
IBM Data Studio gives you the option to select a number of schema objects (or a
subset of them) to add to the overview diagram using the Overview Diagram
Selection window:
Note, however, that the contents of the Overview Diagram
Selection window are entirely dependent on any filters applied to the database
connection object. For example, in Part 1 of this series, I applied a schema
filter to show only the PAULZ schema, which is why that is the only option
returned in the previous window.
If you disable this filter by editing the database
connection or changing an object-specific filter, then the results of such
actions would be taken into consideration when you select the Add to
Overview Diagram option, as shown below:
In the previous figure, you can
see that I disabled the PAULZ-only schema filter by selecting the Disable
filter option. You can change a database-level filter or any database
connection information by selecting the Edit Connection option from the pop-up
menu for a database object.
The following overview diagram
was created in my IDE when I simply selected the PAULZ schema from my filtered
database connection object:
This doesn’t look very helpful, does it? (Rest assured: it
will be.) The IDE doesn’t automatically adjust or zoom into this diagram
because it has the potential to be huge. To enlarge this diagram simply
double-click the title bar (
)
and it will expand to fill the entire IDE. It should now look like this:
In this example, it’s still not that helpful because there
are a lot of relationships in the SAMPLE database. IBM Data Studio provides an Outline
view, which you can use to navigate large diagrams:
In the previous figure, you can see the linkage between the Outline
view on the right, and the corresponding magnified view in the designer
palette. There is more to the Outline view, but I’ll cover all of its
capabilities in a future article.
You can further customize how the storage diagram looks by using
the Properties tab, or by adding meta-data shapes and notes (such as grouping
a set of related tables in a polygon or adding a note to an object describing
its business use). For example, in the following figure, I used the Properties
tab to include column names, types, and so on:
There are lots of features associated with overview diagrams,
and I’ll cover those in my next article.
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