This section defines the following message:
a generalized query, compatible with previous releases of HL7 (henceforth referred to as the original query)
An Embedded Query Language query, which supports free-form select statements, based on the query language of choice (e.g., SQL)
a virtual table request query which supports queries against server database tables (virtual or actual) based on specific selection criteria
a stored procedure request, which enables an application on one system to execute a stored procedure on another system, which is coded to extract specific data
a generalized display response message in which the responding system formats the data for direct output to a display device (in both original and enhanced modes)
an event replay request message, which is used to request data formatted as an event replay response
a tabular response message in which the responding system formats the data in a relational format, as rows and columns
an event replay response, in which the responding system formats the data on the basis of an application-specific-segment-oriented (record-oriented) message
Note : The response paradigm and basic form of the original mode record oriented query are defined in this chapter, while the detailed forms are defined in the functionally-specific chapters. |
The following represents typical examples of queries supported by the Standard:
a) for data regarding a single patient, e.g., send all lab results for patient #123456
b) for data regarding multiple patients, e.g., send the list of patients whose attending physician is Dr. #123
c) for data that is not patient related, e.g., send the age specific normal values for serum protein
The variety of potential queries is almost unlimited. There was no attempt here to define a Standard that would cover every possible query. Instead, the Standard embraces the most common queries that are likely to occur in a hospital. For each common query there is a corresponding unsolicited update. See Section 2.14.2, "UDM/ACK - unsolicited display update message (event Q05)."
In particular, there is no implication that a specific system must support generalized queries to comply with the Standard. Rather, these transactions provide a format, or a set of tools to support queries to the extent desired by the institution. The resources available and local policies will influence the type of queries that are implemented.