This page is for data modellers. It explains the properties for database collectors.

Overview

A database collector reads data from a Datasource. It holds the SQL that will be sent to the datasource to retrieve data. The query columns must match up to any tables saving the data.

To add a new database collector to an analysis model:

1. Go to the model's toolbar → Create group.
2. Click

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    to expand the menu.
3. Drag a 

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    onto the analysis model.

To add an existing database collector to an analysis model, in the model diagram toolbar:

1. Go to the model toolbar → List group.
2. Click

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    to expand the menu.
3. Click 

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     to open the list of available database collectors.
4. Drag a database collector into the analysis model.

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Basic Settings

Advanced

Statement Expressions

Testing Expressions 

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When the database collector is enabled, the properties menu at has an option Image Modified Run Query and See Result. If you cannot see the option, click on

Use Image Modified Run Query and See Result to test the SQL query string in the expression. PhixFlow runs the SQL and opens a table showing the first page of returned data. You can Image Modified Run Query even if the database collector has not been saved.

Query Strings 

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The query string must return data in fields with the same name as the attributes you wish to populate. So to collect data into a table with the attributes account_number, cust_ref and eventsource from a table with fields account_number, customer_ref and eventsource, use the query string:

select account_number, customer_ref as cust_ref, eventsource from billing_products where from_dat >= to_date({_fromDate}, 'yyyymmdd') and to_dat <= to_date({_toDate}, 'yyyymmdd')

Notice that the query string directly includes PhixFlow Expressions that calculate values.

Expressions must be

enclosed in curly brackets, starting with a { and ending with } 

take the form of a standard PhixFlow Expression. Expressions can include PhixFlow's Internal Variables. In the example above, {_fromDate} and {_toDate} are expressions that use internal variables to reference the table's period.

If the dates include a time element, use the query string:

select account_number, customer_ref as cust_ref, eventsource from billing_products where from_dat >= to_date({_fromDate}, 'yyyymmdd.hh24miss') and to_dat <= to_date({_toDate}, 'yyyymmdd.hh24miss')

Complex Replacement Expressions

You can use more complex PhixFlow expressions in queries where necessary. To do this, precede the expression (inside curly braces) with an = sign. For example

select account_number, customer_ref from account{=accBlockString(_out.BlockID)}

There are some disadvantages when using = to precede an expression, as noted below, and therefore you should only use this when really necessary. For example, where the table or column names can vary, and are controlled by input data to the query - as in the above example, where part of the name of the table being queried is returned by a Macro "accBlockString", based on an input value "_out.BlockID".

Note: when you use the = sign to precede an expression, this may result in slower performance. If you are using this to apply a data transformation within the query, it is better to apply this transformation to the input data before you pass it into the query. This is because without the = sign PhixFlow can make use of more efficient query techniques (such as using bind variables) to optimise performance of the queries.

Note: when you use the = sign to precede an expression, PhixFlow does not automatically map PhixFlow types to database types. This means, for example, that if you pass a String PhixFlow type into a query without = you need only

{_out.CustName}

but with = you need to format the string in the query as required by the syntax of the source database, for example

{="'" + _out.CustName + "'"}

Similarly dates in expressions preceded by = must be formatted as required by the syntax of the source database.

Merging Directly from a Database Collector

If you are collecting data directly into a merge, your query must match the ordering represented by the grouping in the input pipe from the collector into the merge. For example, if you have specified Customer and Product as the grouping attributes on the pipe connecting the collector to the table then you must include the appropriate order by expression in the SQL to ensure the data is sorted by customer and then product.

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Generate a Tablefrom a Query

From the hover menu from a database collector on a Analysis Model Window and Toolbars, clicking  creates a new Table with the attributes implied by the query. If the Datasource Instance Expression has been entered then the expression will be used to select the datasource, otherwise the first datasource instance alphabetically will be used. The new table will be shown on the model, connected to this database collector.

To use this feature, the supplied query must be pure SQL i.e. should not contain embedded expressions (as described above).

PhixFlow wraps the query with a "where 1= 0" to avoid a long running statement.

Time Data