Overflow and Truncation

Some operations can result in data overflow or truncation. Overflow results in loss of data on the left. Truncation results in loss of data on the right.

Overflow or truncation can occur in several instances as follows:

During arithmetic operations, for example, when multiplication results in a number larger than the maximum value allowable in its type. Arithmetic operations are defined inChapter 8 “Expressions”
When using aggregate functions, for example, when the sum of several numbers exceeds the maximum allowable size of the type involved. Aggregate functions are defined in Chapter 8 “Expressions”
During type conversion, as when an INTEGER value is converted to a SMALLINT value. Type conversion is discussed later in this chapter.

Because large integers (less than -2147483648 (-2³¹) or larger than 2147483647 (2³¹-1) up to 15 digits long) are stored as decimals, large integer overflow actually results in a DECIMAL OVERFLOW message.

Overflow always causes an error.

Truncation can cause a warning for the following types of data:

Alphanumeric data—A warning occurs if a string is truncated because it is too long for its target location. No error is given if truncation occurs on input.
Numeric data—No error or warning occurs when zeroes are dropped from the left or when any digit is dropped from the fractional part of DECIMAL or FLOAT values. Otherwise, truncation of numeric values causes an error.
LONG data—A warning occurs if LONG column data is truncated because it is too long for its target input file. The output file location is modified to fit the LONG column length, so no truncation error occurs on LONG column output. If the file system fills up, or the limit of shared memory is reached, a system error occurs.

Refer to the ALLBASE/SQL Message Manual for information on handling warnings and errors.

Overflow and Truncation

Technical documentation

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