Difference between revisions of "Database Views"

Revision as of 00:04, 23 July 2011

Designer > Data > Database Views

A Database View lets you define a complex data model by specifying a join across Related Objects. Fields from the related records in each object are then available when running a Report, providing greatly augmented reporting capability.

Using a Database View

After a Database View has been created, it can be used as the basis for a Report. (It appears in the Categories tab of a Report, along with other Objects and Database Views.)

Using that Database View, a report operates on "records" that result from combining fields from each of the objects specified in the Database View.

Working with Database Views

Users that have the Customize Objects permission can create a Database View

Considerations

Database Views can be used to build Reports or Web Tabs
Edits to a Database View are only allowed after checking against existing reports
Fields can be removed from the Database View for various reasons - an object can be removed and replaced with a new object or a new set of fields can be selected
If any fields that are being removed are used in reports based on this Database View, the edits to the Database View will not be allowed; You will have to remove the fields from the affected reports before completing the edit on this Database View

Create or Edit a Database View

To create or edit a Database View:

Click Designer > Data > Database Views
Choose one of the following options:
- Click the [New Database View] button to create a new Database View
- Click the name of the Database view to edit
In the Select tab, specify the objects to use in the Database View. (more below)
Note: At least two objects must be selected.
Click [Next]
In the Joins tab, define the relationship (Joins) between the selected objects. (more below)
Click [Next]
Give the database View a name.
Click [Save]

Select Tab

Start by selecting objects to participate in the view.

Select Objects to Join: Select the desired Objects by moving them to the Selected Objects column).
(You need to select two at a minimum, in order to create a join.)

Filter by Record Ownership: For each object use the Checkbox icon to enable filtering by record ownership when creating a Report.
(A report can then be run on all available records, or on records owned by specific users or teams.)

Custom Aliases: This section is relevant only to programmers, who may need to reference the alias (name) for an object in a Database View when using one of the platform APIs.

The alias fields are auto-populated with default values, but can be changed as needed to make programming easier:

The default alias a Built-in or CRM object is the object name.
(These aliases rarely need to be changed.)
The default alias for a Built-in or CRM object is custom_{numeric_object_ID}
These aliases are routinely changed to something more readable, when programmers access them using APIs. Otherwise, they can be left alone.)

Joins Tab

Joins are defined by specifying the fields that link a record in one object to a record in another object.

About Joins

A "join" is a concatenation of fields from two objects that have the same data for a field they have in common (even though the fields generally have different names).

There are three types of joins:

Left-Join
Right-Join
Equi-Join

For example, if object A has records with values 1, 2, 3, 4 in field "x", and object "B" has values 3, 4, 5, 6 in field "y", then the different kinds of "joins" produce rows like the following:

Row	Record data from "A"	Record data from "B"	Type of Join
1 2	x=1, ...field data... x=2, ...field data...	none none	Non-matching rows, returned only in a Left-Join.
3 4	x=3, ...field data... x=4, ...field data...	y=3, ...field data... y=4, ...field data...	Matching rows returned in a left join or right join. The only rows returned by an Equi-Join (typically the default).
5 6	none none	y=5, ...field data... y=6, ...field data...	Non-matching rows, returned only in a Right-Join.

Important:
The "joining fields" should be indexed, for performance. In the example above,
field "x" should be indexed in A, and field "y" should be indexed in B.
Learn more: Indexes

Join Theory

In a join, choose at least one object that contains an ownership record. The reason:

The Filter by Record Ownership option is commonly used for Reports based on Database Views.

About creating joins:

When two objects are selected, a single, mandatory relationship (Join) must be specified
When three objects are selected (e.g. A, B and C), two mandatory relationships must be specified
The drop down lists fields that available for use in a Join.
In general, the following kinds of fields can be used:
- Record ID fields (fields containing a record identifier)
- Lookup fields
- Fields that contain raw data values like number or string.

Note:
One common convention for numeric identifier fields is to end them with '#'.
That convention can make it easier to identify fields that can be used for a join.
For example: SocialSecurity# or Account#.

Rules for Joins

When creating joins, note that each join is dependent on the previously defined join.

For example, consider the case where we have three tables: A, B and C. In these joins, the first join row defines the possibilities for the second row:

A.id <join type> B.id
A.id <join type> C.id

or

A.id <join type> B.id
B.id <join type> C.id

where <join type> is Left, Right or Equi

Example Join

In this example, we have a two objects: instruments and players in a band. As you might expect, the players in the band might play multiple instruments, and multiple instruments may be available to the band members. As is true with many bands, this band needs a drummer, and some players do vocals only.

instrument_ID	Instrument	player_ID	Players	Can Play Instrument
Object A		Object B
IN1	Guitar	P1	Bill Bertie	IN1
IN2	Keyboard	P1	Bill Bertie	IN4
IN3	Drums	P2	Madeline Morris	IN2
IN4	Accordion	P2	Madeline Morris	IN4
		P3	Sissy Smith	IN2
		P3	Sissy Smith	IN4
		P4	Kerry Kline	IN1
		P5	Crissy Clemens
		P6	Gary Green

Left-Join

When objects A and B are related with a Left-Join, the report includes all records in object A, and all matching records in object B. Using the example above, the resulting report would include these records:

instrument_ID	Instrument	Played by
Left-Join Report
IN1	Guitar	Bill Bertie Kerry Kline
IN2	Keyboard	Madeline Morris Sissy Smith
IN3	Drums
IN4	Accordion	Madeline Morris Sissy Smith

Right-Join

When objects A and B are related with a Right-Join, the report includes all records in object B, and all matching records in object A. Using the example above, the resulting report would include these records:

instrument_ID	Instrument	Played by
Right-Join Report
IN1	Guitar	Bill Bertie Kerry Kline
IN2	Keyboard	Madeline Morris Sissy Smith
IN4	Accordion	Madeline Morris Sissy Smith
		Crissy Clemens
		Gary Green

Equi-Join

When objects A and B are related with an Equi-Join, the report includes all records where a record in object B is related to a record in object A. Using the example above, the resulting report would include these records:

instrument_ID	Instrument	Played by
Equi-Join Report
IN1	Guitar	Bill Bertie Kerry Kline
IN2	Keyboard	Madeline Morris Sissy Smith
IN4	Accordion	Madeline Morris Sissy Smith

Create New Reports Using a Database View

To create a new report using a Database View

Create a Database View that includes the Related Objects of interest
From the desired Application, in the Workspace, click the Reports.
The Reports tab opens.
Click the [Add Report] button
In the Category tab, choose the Database View
(Database Views are shown along with the standard single-object report categories.)
The field list for the report includes all fields available in the objects that part of the Database View.

Learn more: Add or Edit a Report

Delete a Database View

To delete a Database View:

Click Designer > Database Views
Click the Delete link next to the Database View to delete it