Inside Macintosh: Interapplication Communication /

Chapter 12 - Data Access Manager

Creating a Query Document

A query document is a file of type 'qery' that contains a 'qrsc' resource and one or more 'wstr' resources, and may contain a 'qdef' resource plus other resources. Query documents make it possible for you to write applications that can communicate with data servers without requiring familiarity with the command language used by the data server. Because a query document is most useful if it can be used by many different applications, no query document should depend on the presence of a particular application in order to function.

An application can call the DBGetNewQuery function to convert a 'qrsc' resource into a query record in memory. A query record specifies connection information and also contains a handle to an array of queries; each query can be either a complete query or a template for a query. If the 'wstr' resource is a template, it contains the commands and data necessary to create a query, without any information that the user must add just before the query is sent. The 'qdef' resource contains a query definition function, which can modify the query record and, if necessary, fill in the query template to create a complete query. The DBStartQuery function sends the query pointed to by a query record to a data server. The following sections describe the contents of a query document, describe query records, and define the 'qrsc', 'wstr', and 'qdef' resources.

---

Subtopics

User Interface Guidelines for Query Documents

Contents of a Query Document

Query Records and Query Resources

Writing a Query Definition Function