Query the Database

This topic is for AquilaCRS

Selecting the Query

The sidebar on the Dashboard page contains a list of queries & searches. To initiate a query just press on the option you require. The options differ only in the data tables they search. For instance, the IBID Query allows you to query the IBID set of data tables.

When you select the Query of your choice, you may need to wait for a few seconds initially whilst all the fields and their parameters are transferred from the server.

Queries have two elements:

• The Filter : this is a set of conditions that determine which rows are returned from the database. E.g. Sex = Male
• Output Fields: this is a set of tickboxes that determine which fields are listed in the query output.

Both elements can be saved to a file before running the query so you can reload & reuse them at a later date. See Saving & Re-Using Filters & Output Field List below.

Entering Criteria

The Filter is defined on a row-by-row basis & you can enter multiple conditions.

• To add your first condition use the press the button to add a new condition.
  • To remove a condition, press the ... button and select Remove Row

• Click on the field name (in green) to open a list of fields in the query.
  • You can select with the mouse, or by starting to type the field name as it's shown.
  • Fields are often prefixed with their section names, e.g. Patient.Given Name.

• Click the operator (in red) to select the comparison type.
  • In character fields, Like can be used instead of Equals to partially match the value you enter.
    • E.g. Patient.Town like chester will match manchester and chester, but Patient.Town equals chester will only match Chester.
  • In name fields, Like will perform a sounds like match.
• Click on the value (in blue) to change it. The type of editor you're presented with depends on the type of the field you're comparing. E.g. a date field will show a date editor, a drop-down field will show the same drop-down options.

By default, the conditions you enter are combined using the logical operator and. This is shown at the top of the filter, at the <Root> level. This means that all conditions you specify must be met for a row of data to be returned. Set this to Or to have rows returned where a row matches any condition.

A filter definition can be saved to a file before running the query so you can reload & reuse it at a later date. See Saving & Re-Using Filters & Output Field List below.

Filter Groups

In some circumstances you may have a complex filter to define that requires all of certain conditions to be met and any of some other conditions. We would achieve this effect by using a condition group. A group of conditions has their own operator (and/or) that is treated separately from the <root> conditions.

This is best demonstrated by example:

The above conditions can be summarised as follows:

 (Record type is acute major) OR (Intubated AND Inhale Severity is Severe or Moderate)

or in more database-like form:

([Record Type] = 'Acute major') OR ( ([Intubated] = TRUE ) AND ( ([Inhale Severity] = 'Severe') OR ([Inhale Severity] = 'Moderate') ) )

Selecting Fields to Output

As the Filter section defines which rows to return, so the Output Fields list defines which columns to return. The list of available fields are displayed in a hierarchical view, grouped by logical section.

You can select to return all the columns for a specific section by ticking that section. You can also open the branch for that section and (de)select fields individually.

Any fields used in the filter (see above) are automatically added to your output fields.

To save bandwidth in what are often overworked networks, it's always a good idea to spend a few minutes carefully selecting only those fields that you need for your analysis.

A field list definition can be saved to a file before running the query so you can reload & reuse it at a later date. See Saving & Re-Using Filters & Output Field List below.

Saving & Re-Using Filters & Output Field List

The Query form allows you to save & load both the filter and output fields for future use. This is incredibly useful for saving & recalling standard filters & output field lists.

On the filter screen, press the Options button to reveal a list of save/load options. In all cases, use a meaningful filename to allow easier recalling.

• Load Filter from File: Opens a previously saved filter & replaces any current conditions in the filter window with those from the file.
• Save Filter to File: Saves the conditions in the filter to a file. This file can be re-used by any AquilaCRS installation, so feel free to share assuming there is no patient identifiable information in the conditions.
• Load Fields from File: Opens a previously saved list of fields & replaces any current selections with those from the file.
• Save Fields to File: Saves the current output fields selection to a file. As with the filter, the file can be shared amongst any AquilaCRS installation.

Query Results

See Query results for more information