NVL2 is a scalar function whose return data type depends on the data types associated with the arguments passed to the function.

- If expr2 and expr3 are numeric types, the function determines which argument has the highest precedence, converts the other argument to that data type, and returns that data type. For details about the order of precedence, see “Compatible Types” in
Teradata Vantage™ SQL External Routine Programming
, B035-1147
.
If that data type is DECIMAL/NUMERIC and the precision and scale of the two arguments are different, the precision and scale of the return type will be set to achieve the maximum precision possible. For example, if the input arguments are DECIMAL(6,3), DECIMAL(7,4), and DECIMAL(8,7), the return type would need three digits to the left of the decimal point and seven digits to the right of the decimal point to avoid any reduction in precision. In this case, the return data type is set to DECIMAL(10,7)

In cases where it is not possible to maintain the maximum precision, the data will be rounded according to the DBS Control Record RoundHalfWayMagUp field. For example, if the two arguments are DECIMAL(32, 8) and DECIMAL(30, 28), the return type will be DECIMAL(38,14). This will allow for 24 digits to the left of the decimal point (required for the DECIMAL(32,8) argument), and 14 digits to the right of the decimal point.

If the data type is fixed point NUMBER and the precision is less than or equal to 38, the precision and scale of the return type are calculated with the same method used for DECIMAL/NUMERIC. However, if the precision is greater than 38, the return type is changed to NUMBER(*) to avoid loss of accuracy. If the data type is floating point NUMBER, the return type is NUMBER(*).

- If expr2 and expr3 are character types, the function converts the second argument to the data type of the first argument and returns the type as VARCHAR.

You can also pass arguments with data types that can be converted to the above types using the implicit data type conversion rules that apply to UDFs.