Whenever Sybase IQ requires an explicit or implicit conversion from one data type to another during a query or insert, it always truncates the results.
When you explicitly convert data from a higher scale to a lower scale, Sybase IQ truncates the values in the results. For example, if you CAST a column value in a query to a scale 2 when it is stored with a scale 4, values such as 2.4561 become 2.45.
When Sybase IQ implicitly converts from a higher scale to a lower scale during an insertion, it truncates the values before inserting the data into the table. For example, if you insert from one table with a data type of NUMERIC(7,3) to another table with a data type of DECIMAL(12,2), values such as 2.456 will become 2.45.
When an arithmetic operation results in a higher scale than the predetermined scale, Sybase IQ truncates the results to fit the scale after it has been determined using the rules defined in Reference: Building Blocks, Tables, and Procedures > SQL Data Types > Numeric data types.
If your results require rounding of the values instead of truncation, you should use the ROUND function in your command. However, for inserts, the ROUND function can only be part of its query expression.
The maximum precision for numeric data is 126.