SUM is valid only for numeric data.
Nulls are not included in the result computation. For details, see “Manipulating Nulls” in Teradata Vantage™ - SQL Fundamentals, B035-1141 and Aggregates and Nulls.
The SUM function can result in a numeric overflow or the loss of data because of the default output format. If this occurs, a data type declaration may be used to override the default.
For example, if QUANTITY comprises many rows of INTEGER values, it may be necessary to specify a data type declaration like the following for the SUM function:
SUM(QUANTITY(FLOAT))