NULL_PROCESSOR Function
Facilitates the use of the Null_Info keyword for the DB_SQL function by extracting the list of rows containing missing for one or more columns.
Usage
table = NULL_PROCESSOR (null_info_object, ['col1', 'col2', ..., 'coln'], Comp=comp)
Input Parameters
null_info_object—The object returned by the Null_Info keyword in the DB_SQL call.
coli—The list of column names.
Keywords
Comp=comp—Produces the complement to the result, that is, the result contains a list of rows with missing data. comp contains a list of rows with no missing data.
Discussion
Assuming the following use of the ODBC_SQL Null_Info keyword:
table=odbc_sql(odbc_connect('oracle', 'user_id/user_pw'), 'select * from blanktest', null_info=foo)
where blanktest
contains the data given in blanktest Data , which has missing data for ID_NO in the 4th, 9th, and 11th rows and missing data for ANIMAL_NAME in the 3rd, 8th, and 10th rows.
ID_NO |
ANIMAL_NAME |
1 |
golden |
2 |
chirpy |
3 |
NULL |
NULL |
harry |
5 |
KC |
6 |
skip |
7 |
sparky |
8 |
NULL |
NULL |
sneakers |
10 |
NULL |
NULL |
harvey |
Note: NULL indicates a NULL value in the corresponding database field.
Then,
jjj=NULL_PROCESSOR(foo,['ID_NO','ANIMAL_NAME'],Comp=comp)
produces the results
jjj = 2 3 7 8 9 10
comp = 0 1 4 5 6
This output can be utilized as in the following examples.
Table2 = table(comp)
produces a table with only rows and no missing values, as shown in Table2, or as in blanktest Data .
ID_NO |
ANIMAL_NAME |
1 |
golden |
2 |
chirpy |
5 |
KC |
6 |
skip |
7 |
sparky |
Then,
Table3=table(jjj)
produces a table, as shown in Table3, containing only rows with missing data (note how zeros have been substituted for values of ID_NO that are missing).
ID_NO |
ANIMAL_NAME |
3 |
|
0 |
harry |
8 |
|
0 |
sneakers |
10 |
|
0 |
harvey |
Instead, if you want only the locations where one field is missing, a different db_sql call, jjj=foopro(foo,['ID_NO'],Comp=comp)
, returns an array, jjj
, with the rows where ID_NO is missing (3 8 10
).
Remember that rows are counted beginning with 0.