The ROW data type holds a tree structure. A row in a database is a particular type of tree structure, but the ROW data type is not restricted to holding data from database rows.
Root Row PartNumber = 1 Description = 'Chocolate bar' Price = 0.30 Row PartNumber = 2 Description = 'Biscuit' Price = 0.35 Row PartNumber = 3 Description = 'Fruit' Price = 0.42
In the example, Root contains three elements all named "Row". Each of these in turn contains three elements with different names and values. This diagram equally describes an instance of an ESQL row data type (that is, a tree structure) or the contents of a database table.
The ROW data type is a normal data type. You can use the DECLARE statement to create ROW variables in the same way as you create INTEGER or CHARACTER variables. There is also a more general concept of a ROW data type. In the previous example, Root is the root element of a ROW variable. Each of the elements called "Row", while not the root element of ROW variables, are the root elements of sub-structures. Many ESQL operations (and particularly the SELECT function) work with the general concept of ROW and will operate equally on whole trees or parts of them.
There is also a general concept of a LIST data type. The set of elements called "Row" can be regarded as a list. Some ESQL operations (particularly SELECT) work with the general concept of list.
InputRoot, OutputRoot (and so on) are examples of ROW variables that are automatically declared and connected into the broker's structure, ready for use.
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