Comparing records
Records can be compared with the ==
comparison operator and the
.*
notation.
It is possible to compare records by using the
.*
notation and the ==
or !=
operators:IF rec1.* == rec2.* THEN
...
END IF
All members will be compared individually.
Important: If the record contains members of type
ARRAY[n]
, DYNAMIC ARRAY
,
DICTIONARY
or TEXT/BYTE
, the comparison will always evaluate to
FALSE
, except when TEXT/BYTE
members are NULL
in
both records. Consider testing each record member individually. The size of the
TEXT/BYTE
members can be compared with the LENGTH()
function.If the record contains several levels of sub-records, all sub-records will be processed recursively.
If two record members are NULL
, the result of this member comparison is
TRUE
.
If two corresponding members do not contain the same value, or one of them is
NULL
, the records are considered as different.
Tip: Record comparison can be used to implement optimistic locking for database updates.
For more details, read the SQL programming
guide.
The next code example shows how to compare two records defined from the same
type:
TYPE t_cust RECORD
id INTEGER,
name VARCHAR(50),
address RECORD
num VARCHAR(5),
street VARCHAR(100)
END RECORD
END RECORD
MAIN
DEFINE r1, r2 t_cust
LET r1.id = 999
LET r1.name = "Mike Torme"
LET r1.address.num = "2A"
LET r1.address.street = "Sunset bld"
LET r2 = r1
DISPLAY "1: ", IIF( r1.* == r2.*, "Equals", "Differs" )
LET r2.name = "Mike Torm"
DISPLAY "2: ", IIF( r1.* == r2.*, "Equals", "Differs" )
LET r2.name = NULL
DISPLAY "3: ", IIF( r1.* == r2.*, "Equals", "Differs" )
END MAIN
Output:
1: Equals
2: Differs
3: Differs