There is a system column OLD_DATA_TYPE that is available in the _USER_COLUMNS system table. The column type is a long integer and this column stores the 4D data type of a given column.

This value is different from the DATA_TYPE column, which represents the SQL data type of a given column. See the Tech Tip 4D Data Types in SQL System Tables for more information on the DATA_TYPE column.

Here is a table which shows the 4D field types and the corresponding values for DATA_TYPE and OLD_DATA_TYPE:

Field type	DATA_TYPE	OLD_DATA_TYPE
Alpha	10	0
BLOB	18	-1
Boolean	1	6
Date	8	4
Float	7	-7
Integer	3	8
Integer 64 Bits	5	-5
Long Integer	4	9
Picture	12	3
Real	6	1
Text	10	2
Time	9	11

This information can be used to extract information about a field, given its tablename and fieldname.

For more information on system tables see the 4D SQL Reference, "Principles for integrating 4D and the 4D SQL engine".

Note: This column was introduced in 11.2.