isSQLNullable

The isSQLNullable property indicates whether the field can be set to a null value. The property is available only for fields in an SQL record. Valid values are NO (the default) and YES.

EGL maintains this property for compatibility with earlier versions. For new code, use the "?" type extension character to indicate a nullable variable. For more information, see Type extension characters and Null values and the nullable type.

Variables made nullable with a "?" are slightly different than variables made nullable with {isSqlNullable = YES}. When the nullable variable has a null value and is used in an expression with more than one operand, it has the following value:
Consider the following examples:
Record mySQLRecord type SQLRecord
	anInt INT {isSQLNullable = YES};
end
...
myRec mySQLRecord;
result, anotherInt INT?;

myRec.anINT = NULL;
result = myRec.anInt + 1;
Here the result is 1 because EGL ignores the null flag when evaluating the expression.
anotherInt INT? = NULL;
result = anotherInt + 1;
Here the result is a null value because EGL takes the null flag into account (if any operand has a null value, the result of the numeric expression is null).
If a given field in an SQL record is nullable, the following features are available:

Feedback