NULL_PROCESSOR Function

Database Connection User Guide > Reference > 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 DB_SQL Null_Info keyword:

table=db_sql(db_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.

Table 2-1: blanktest Data
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.

Table 2-2: Table2
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).

Table 2-3: Table3
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.

Version 2017.0