I have below query which i am trying to run but not returning the expected result. The ISIN field value which is Null in EXPORT_BB is also getting ignore and not showing the result with the condition given in NOT IN clause. The export_blacklist has only one row value and which is not Null but still i dont for what reason the null value is getting ignored.
Select * from EXPORT_BB where ISIN NOT IN
(
SELECT
ISIN
FROM
export_blacklist);
If i run only select query without the NOT IN clause then i can see values which is NULL for ISIN field.
JUst for test i tried below query and its also resulting nothing. Is it bug in Oracle 18c or something is missing?
select 'null is not in set' from dual where null not in (select 1 from dual);
Any comparison of NULL with =, <>, <, > or in a IN or NOT IN clause will return NULL, so that row is not included in the results (because only rows for which the returned value is TRUE will be included in the results).
Change your code with a condition for the case that ISIN is NULL:
SELECT * FROM EXPORT_BB
WHERE ISIN NOT IN (SELECT ISIN FROM export_blacklist)
OR ISIN IS NULL
NULL values doesn't work with NOT IN it's the normal behaviour.
You have to convert the NULL to another value to be able to operate with it or use IS NULL/IS NOT NULL
Select * from EXPORT_BB where NVL(ISIN, 999999) NOT IN
(
SELECT
NVL(ISIN, 999999)
FROM
export_blacklist);
Comparing to a null value in Oracle always returns false.
Is NULL >= 1? No.
Is NULL < 1? No.
Is NULL in your set? Regardless of what your set is, the answer is no.
Is NULL not in your set? Again, no.
It is the expected behaviour. NOt related to 18c it is the same way from Oracle 7 onwards
NOT IN doesnt consider nulls.
NOT EXISTS does consider nulls.
Consider the following example in db fiddle
https://dbfiddle.uk/?rdbms=oracle_18&fiddle=8be0a790d8172093a032602345038e8e
See a discussion on this
https://asktom.oracle.com/pls/apex/asktom.search?tag=in-vs-exists-and-not-in-vs-not-exists
As you have been answered by collegues you have to specify that you wanna return null values too.
Namely
SELECT *
FROM EXPORT_BB
WHERE ISIN NOT IN (SELECT ISIN FROM EXPORT_BLACKLIST)
OR ISIN IS NULL;
Related
I want to return some data using the following query.
select *
from table
where code_value not in ('44','45','46')
This statement return all expected rows except rows with code_value = null.
I want to get the null columns also.
How can I get that?
Use IS NULL :
WHERE (code_value IS NULL OR code_value not in ('44','45','46'));
NOT IN will not return records when compared against an unknown value or NULL values.
The direct comparison to NULL is the right solution. But I offer this to illustrate the "inverse" of IN. It is more like:
select t.*
from t
except
select t.*
from t
where code_value not in ('44', '45', '46');
Than not in. This is not even exact either, because except removes duplicates. But it is logically closer to the inverse.
I would do it using isnull in conjunction with a default value which doesn't exist in the code_value;
select *
from table
where isnull(code_value,'<<non existing value>>') not in ('44','45','46')
I would like to retrieve all rows with values except 1,2,3,4,5 in my COLUMNA in TABLEA .
SELECT * FROM TABLEA WHERE COLUMNA NOT IN (1,2,3,4,5)
But this eliminates the rows with NULL values in COLUMNA too.
I don't want to eliminate NULL values rows and would like to include those rows in the resultset.
Alternatively, I can try below query for the same
SELECT * FROM TABLEA WHERE COLUMNA NOT IN (1,2,3,4,5) OR COLUMNA IS NULL.
But I would like to know, why is it necessary to add this OR condition?
Why is the additional necessary?
NULL comparisons almost always results in NULL, rather than true or false. A WHERE clause filters out all non-true values, so they get filtered out.
This is how SQL defines NULL. Why is NULL defined like this?
NULL does not mean "missing" in SQL. It means "unknown". So, the result of <unknown> not in (1, 2, 3, 4, 5) is "unknown", because the value could be 1 or it might be 0. Hence it gets filtered.
I will also note that the SQL standard includes NULL-safe comparisons, IS NOT DISTINCT FROM and IS DISTINCT FROM corresponding to = and <> respectively. These treat NULL as just "any other value", so two NULL values are considered equal. However, there is no construct for NULL-safe IN and NOT IN, as far as I know.
Try the following:
SELECT * FROM TABLEA WHERE ISNULL(COLUMNA,0) NOT IN (1,2,3,4,5)
Total number of records in table i1450:
Total number with condition where i.BROJ is equal to field REFERENCA in other table:
Shouldn't it return difference between last two results (which is 64) when I use NOT IN in WHERE clause?
Both of columns are of varchar type.
If you have any NULL values in the REFERENCA column from the FpsPmtOrderRQ table then the NOT IN clause will not work as expected - (the reason why)
A solution is to remove NULL values from the result returned by the subselect.
SELECT COUNT(*)
FROM i1450 j
WHERE i.BROJ NOT IN (SELECT REFERENCA FROM FpsPmtOrderRQ WHERE REFERENCA IS NOT NULL)
If the sub-query returns a null value, the IN will not be true. Do NOT EXISTS instead.
select count(*)
from i1450 i
where not exists (select 1 from FpsPmtOrderRQ f
where i.broj = f.REFERENCA)
I think you need to coalesce your field to handle nulls. That is probably why you get 0.
By doing:
where coalesce(I.BROJ,'n/a') not in (select coalesce(REFERENCA,'')
or something similar, you would exclude nulls, and return a proper count.
I don't understand why this query doesn't work.
I have a table which is full of rows where 3 of the column values are set to NULL.
But when I run the following query, it returns 0 (it should return 96)
SELECT COUNT(*) FROM SEAT WHERE BOOKED=null;
Do you know what I am doing wrong?
It depends on your database settings and the specific RDBMS you are using, but if you are using ANSI NULL syntax you cannot directly compare a value to NULL with an equality test (=) -- it will always fail.
Use WHERE BOOKED IS NULL instead.
You have to use IS NULL instead of = null
Since null technically isn't a value, you can't compare null using the = operator.
Use IS NULL
SELECT COUNT(*)
FROM SEAT
WHERE BOOKED IS NULL
How do you write a SELECT statement that only returns rows where the value for a certain column is null?
Do you mean something like:
SELECT COLUMN1, COLUMN2 FROM MY_TABLE WHERE COLUMN1 = 'Value' OR COLUMN1 IS NULL
?
I'm not sure if this answers your question, but using the IS NULL construct, you can test whether any given scalar expression is NULL:
SELECT * FROM customers WHERE first_name IS NULL
On MS SQL Server, the ISNULL() function returns the first argument if it's not NULL, otherwise it returns the second. You can effectively use this to make sure a query always yields a value instead of NULL, e.g.:
SELECT ISNULL(column1, 'No value found') FROM mytable WHERE column2 = 23
Other DBMSes have similar functionality available.
If you want to know whether a column can be null (i.e., is defined to be nullable), without querying for actual data, you should look into information_schema.
Use Is Null
select * from tblName where clmnName is null
You want to know if the column is null
select * from foo where bar is null
If you want to check for some value not equal to something and the column also contains null values you will not get the columns with null in it
does not work:
select * from foo where bar <> 'value'
does work:
select * from foo where bar <> 'value' or bar is null
in Oracle (don't know on other DBMS) some people use this
select * from foo where NVL(bar,'n/a') <> 'value'
if I read the answer from tdammers correctly then in MS SQL Server this is like that
select * from foo where ISNULL(bar,'n/a') <> 'value'
in my opinion it is a bit of a hack and the moment 'value' becomes a variable the statement tends to become buggy if the variable contains 'n/a'.
select Column from Table where Column is null;
select * from tableName where columnName is null
For some reasons IS NULL may not work with some column data type. I was in need to get all the employees that their English full name is missing, I've used:
SELECT emp_id, Full_Name_Ar, Full_Name_En
FROM employees
WHERE Full_Name_En = '' or Full_Name_En is null