If you specify Statistics analysis, Data Explorer performs Statistics analysis (described in Statistics) on every specified input table column of numeric or date type, using this procedure:
- Combine as many counts for the columns in as few SELECT statements as possible.
- Put results in a temporary table. (Each SELECT statement is an INSERT SELECT statement.)
- Use INSERT SELECT statements to reorganize data for possibly multiple columns and move it to the output table.
Data Explorer uses the Teradata aggregations for minimum, maximum, mean, standard deviation, skew, and kurtosis. With statisticalmethod=population (the default), Data Explorer uses formulas expressing population skew and population kurtosis in terms of their sample counterparts.
You can specify the statistics to calculate (see statsoptions in Syntax). However, if you specify Histogram analysis, Data Explorer always calculates minimum, maximum, mean and standard deviation.
For all but count, minimum, and maximum, Data Explorer first converts date columns to the number of days since 1900.