Data Transformation Engine Database Interface Designer Reference Guide

Chapter 4 - Database Type Trees Table and Query Type Tree Structure

Database Interface Designer Reference Guide

♦ In the third record (which has no Part_Name), the value in the Unit_Price

column is zero. The Sizeof value for the Unit_Price column remains at four

and the Unit_Price column contains the value zero.

♦ In the last record (

DooDad), there is no value in the Unit_Price column nor in

the Picture column. Therefore, the Sizeof value for both columns is zero.

Delimiters (|) are included as placeholders for the Unit_Price column.

Column Types for Expressions

Each constant or function specified in a query is given a name based upon the

name returned from the database driver to the database adapter. If the database

driver does not return a name for a column in the results, the item type created

for the column is given a name beginning with Expr and is concatenated with a

number beginning with 1000 for the first constant or function, 1001 for the

second, and so on.

For example, the type tree generated for the following query

SELECT MIN(salary), MAX(salary) FROM Employee

would have a Row with two columns representing the result of the SQL MIN and

MAX functions. In the type tree, the items created to represent the results of

these functions would be Expr1000 and Expr1001 for the MIN and MAX functions,

respectively, as indicated in the following example.