T24 User Guide - Page 23

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T24 Application Development

Implementing the Queries

The implementation of each query is in the DAS subroutine itself. This must be created from the

template DAS.TEMPLATE, and each query is an additional CASE statement based on MY.CMD,

which holds the name of the query.

In addition to the queries defined specifically for the application, the generic query

DAS$ALL.IDS is

defined to return all the keys on the table. It is only necessary to include this query in the DAS if this

list can be cached, i.e. the contents of the table are static at run time.

CASE MY.CMD = DAS$ALL.IDS ; * Standard to return all keys

ADD.TO.CACHE = 1

Simple queries define the fields, operands and the data to query. The data may be literals:

CASE MY.CMD = dasExamplesInterestSchedules;* All interest schedules

MY.FIELDS = 'SCHEDULE.TYPE'

MY.OPERANDS = 'EQ'

MY.DATA = 'INTEREST'

Common variables:

CASE MY.CMD = dasExamplesTodaysSchedules;* All schedules due today

MY.FIELDS = 'SCHEDULE.DATE'

MY.OPERANDS = 'EQ'

MY.DATA = TODAY

Or use variable criteria that is supplied when the DAS is invoked:

CASE MY.CMD = dasExamplesDealsOfAType ;* Contracts of a certain DEAL.TYPE

MY.FIELDS = 'DEAL.TYPE'

MY.OPERANDS = 'EQ'

MY.DATA = THE.ARGS

More complex queries are defined by adding fields to the arrays, and specifying the MY.JOINS array:

CASE MY.CMD = dasExamplesCustomerCurrency; * For a customer with given CCY

MY.FIELDS = 'CUSTOMER'

MY.OPERANDS = 'EQ'

MY.DATA = THE.ARGS<1>

MY.JOINS = 'AND'

MY.FIELDS<2> = 'CURRENCY'

MY.OPERANDS<2> = 'EQ'

MY.DATA<2> = THE.ARGS<2>

Caching Query Results

The DAS infrastructure allows the caching of results by setting:

ADD.TO.CACHE = 1

Once the query results have been returned, they are added to the cache mechanism and further

invocation of the named select will always use the cached results. The cache must ONLY be used

where the result of the query is static at run time, e.g. CATEGORY or COMPANY. Caching must NOT

be used where variable data is used in the selection.

TEMENOS T24 User Guide Page 23 of 34

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