I have a question regarding handling NULL value in a column in ORACLE Table.
So, when i query a table, i get this error message in every NULL value occurences
Notice: Undefined index: STATUS in C:\xampp\htdocs\WeltesInformationCenter\AdminLTE\pages\tables\assignmenttable.php on line 481
my query is like this
SELECT MASTER_DRAWING.*, (SELECT PREPACKING_LIST.PACKING_STATUS FROM PREPACKING_LIST WHERE MASTER_DRAWING.HEAD_MARK = PREPACKING_LIST.HEAD_MARK) STATUS FROM MASTER_DRAWING WHERE PROJECT_NAME = :PROJNAME
My question is, how to handle NULL value so that when it sees a null value, it can return some value such as 0 or any string.
Thanks
Try
SELECT MASTER_DRAWING.*,
NVL((SELECT PREPACKING_LIST.PACKING_STATUS
FROM PREPACKING_LIST
WHERE MASTER_DRAWING.HEAD_MARK = PREPACKING_LIST.HEAD_MARK),'N/A'
) STATUS
FROM MASTER_DRAWING WHERE PROJECT_NAME = :PROJNAME
Related
output--
I have written the query in snowflake to generate Json file, from the query output want to remove fields which has NULL. OBJECT_CONSTRUCT is not working properly for some column its not passing NULL value where else for some column its giving null value as result.
Input-
Json remove any field which has value NULL or blank.
{"DIFID":122,"DIF_FLAG":"NULL","DIF_TYPE":"asian/white","FOCAL_COUNT":2370,"REFERENCE_COUNT":17304},
Required Output-
Json remove any field which has value NULL or blank.
{"DIFID":122,"DIF_TYPE":"asian/white","FOCAL_COUNT":2370,"REFERENCE_COUNT":17304},
query-
select distinct ITEMSTATID,object_construct(
'DIFID',DIFID,
'DIF_TYPE',DIF_TYPE,
'DIF_FLAG',DIF_FLAG,
'FOCAL_COUNT',FOCAL_COUNT::integer,
'REFERENCE_COUNT',REFERENCE_COUNT::integer,
'DIF_METHOD',DIF_METHOD,
'DIF_VALUE',DIF_VALUE)
DIF
from DEV_IPM.STAGEVAULT.DIF_STATISTICS;
For string column and 'NULL' as string literal column's value is not skipped:
CREATE OR REPLACE TABLE DIF_STATISTICS
AS
SELECT 1 AS ITEMSTATID,
122 AS DIFID,
'NULL' AS DIF_FLAG, -- here
'asian/white' AS DIF_TYPE,
2370 AS FOCAL_COUNT,
17304 AS REFERENCE_COUNT;
Output:
The value is definitely stored as TEXT:
SELECT null AS DIF_FLAG, 'NULL' AS DIF_FLAG;
On the left: true NULL on the right: NULL string
If it the case then it should be nullified NULLIF(DIF_FLAG, 'NULL') before passing to OBJECT_CONSTRUCT function:
SELECT ITEMSTATID,
object_construct(
'DIFID',DIFID,
'DIF_TYPE',DIF_TYPE,
'DIF_FLAG',NULLIF(DIF_FLAG, 'NULL'),
'FOCAL_COUNT',FOCAL_COUNT::integer,
'REFERENCE_COUNT',REFERENCE_COUNT::integer) AS DIF
FROM DIF_STATISTICS;
Previous answer before column details were provided (also plausible):
It is working as intended:
NULL Values
Snowflake supports two types of NULL values in semi-structured data:
SQL NULL: SQL NULL means the same thing for semi-structured data types as it means for structured data types: the value is missing or unknown.
JSON null (sometimes called “VARIANT NULL”): In a VARIANT column, JSON null values are stored as a string containing the word “null” to distinguish them from SQL NULL values.
OBJECT_CONSTRUCT
If the key or value is NULL (i.e. SQL NULL), the key-value pair is omitted from the resulting object. A key-value pair consisting of a not-null string as key and a JSON NULL as value (i.e. PARSE_JSON(‘NULL’)) is not omitted.
For true SQL NULL values, that column is ommitted:
CREATE OR REPLACE TABLE DIF_STATISTICS
AS
SELECT 1 AS ITEMSTATID,
122 AS DIFID,
NULL AS DIF_FLAG,
'asian/white' AS DIF_TYPE,
2370 AS FOCAL_COUNT,
17304 AS REFERENCE_COUNT;
SELECT ITEMSTATID,
object_construct(
'DIFID',DIFID,
'DIF_TYPE',DIF_TYPE,
'DIF_FLAG',DIF_FLAG,
'FOCAL_COUNT',FOCAL_COUNT::integer,
'REFERENCE_COUNT',REFERENCE_COUNT::integer) AS DIF
FROM DIF_STATISTICS;
Output:
Probably the data type of the column DIFID is VARIANT/OBJECT:
CREATE OR REPLACE TABLE DIF_STATISTICS
AS
SELECT 1 AS ITEMSTATID,
122 AS DIFID,
PARSE_JSON('NULL') AS DIF_FLAG, -- here
'asian/white' AS DIF_TYPE,
2370 AS FOCAL_COUNT,
17304 AS REFERENCE_COUNT;
Output:
What I am trying to accomplish is to update the ISCURRENT field to 'N' and the EFFECTIVE_END_DATE field to the current date if the record of its type does not have the most recent EFFECTIVE_START_DATE.
An error does not get thrown it just tells me "0 rows affected" but I created a record with a more recent EFFECTIVE_START_DATE which should affect the other record in the table that has the earlier EFFECTIVE_START_DATE.
Here is an image of the 2 records I'm using to test it out.
The record that has a KTEXT of '400 Atlantic' should be changed from this script to have an ISCURRENT ='N' and EFFECTIVE_END_DATE=GETDATE() because the record with the KTEXT of 500 Maria has a more recent EFFECTIVE_START_DATE
UPDATE [SAP].[src_gl_sap_m_cepct]
set ISCURRENT='N',
EFFECTIVE_END_DATE=GETDATE()
WHERE NOT EXISTS (SELECT [SPRAS],
[PRCTR],
MAX(EFFECTIVE_START_DATE)
FROM [SAP].[src_gl_sap_m_cepct] AS A
WHERE CONCAT([SAP].[src_gl_sap_m_cepct].[SPRAS],[SAP].[src_gl_sap_m_cepct].[PRCTR]) = CONCAT(A.[SPRAS],A.[PRCTR]
)
GROUP BY [SPRAS],[PRCTR]);
Thank you !
Correct me if I am wrong, but this part of your query
FROM [SAP].[src_gl_sap_m_cepct] AS A
WHERE CONCAT([SAP].[src_gl_sap_m_cepct].[SPRAS],[SAP].[src_gl_sap_m_cepct].[PRCTR]) = CONCAT(A.[SPRAS],A.[PRCTR]
can also be written like this (because you have a self join)
FROM [SAP].[src_gl_sap_m_cepct] AS A
WHERE CONCAT(A.[SPRAS], A.[PRCTR]) = CONCAT(A.[SPRAS], A.[PRCTR]
And like this I notice that you are simply comparing a value to the same value again.
Thus this will always evaluate as TRUE
And thus the not exists clause will never evaluate as true
And therefore no updates will happen.
I think something like this might work for you
UPDATE c
set c.ISCURRENT='N',
c.EFFECTIVE_END_DATE = GETDATE()
FROM SAP.src_gl_sap_m_cepct c
WHERE EXISTS ( select 1
FROM SAP.src_gl_sap_m_cepct AS A
WHERE CONCAT(c.SPRAS, c.PRCTR) = CONCAT(A.SPRAS, A.PRCTR)
AND A.EFFECTIVE_START_DATE > c.EFFECTIVE_START_DATE
)
If I understood correctly, the statement should be like this:
UPDATE c
set ISCURRENT='N',
EFFECTIVE_END_DATE = GETDATE()
FROM [SAP].[src_gl_sap_m_cepct] c
WHERE EXISTS (
SELECT 1
FROM [SAP].[src_gl_sap_m_cepct] AS A
WHERE CONCAT(c.[SPRAS], c.[PRCTR]) = CONCAT(A.[SPRAS],A.[PRCTR])
AND c.EFFECTIVE_START_DATE < A.EFFECTIVE_START_DATE
);
I'm trying to run the following case statement in SQL:
CASE
WHEN P.Photos_Cloned_From IS NULL
THEN 'http://www.toolboxbarn.com/v/vspfiles/photos/'+P.ProductCode+'-2T.jpg'
ELSE 'http://www.toolboxbarn.com/v/vspfiles/photos/'+P.Photos_Cloned_From+'-2T.jpg'
END AS image_link,
The statements works, but only for those records that are not NULL. For items that are NULL, the statement is not returning the THEN condition.
Any suggestions?
Try this and let us know what happens.
'http://www.toolboxbarn.com/v/vspfiles/photos/'+
COALESCE(P.Photos_Cloned_From,P.ProductCode,'DEFAULT')+'-2T.jpg'
AS image_link,
Using coalesce here is better than the case statement. Some platforms can optimize coalesce and it lets you easily make a default value.
#hogan's Suggestion is a great one to save code, but ultimately it should have the same result as your case statement if you don't introduce his new 'default' case. It is most likely that the ProductCode is also NULL is that a possibility?
Why string + NULL = NULL because NULL is an unknown in sql most db platforms will nullify the entire value when null is aggregated or concatenated.
So Think of the following test cases:
Id ProductCode Photos_Cloned_From
1 1 ClonedFrom
2 2 Null
3 NULL Null
The results of your case expression and Hogan's Suggestion would be:
1) ELSE 'http://www.toolboxbarn.com/v/vspfiles/photos/ClonedFrom-2T.jpg'
2) WHEN 'http://www.toolboxbarn.com/v/vspfiles/photos/2-2T.jpg'
3) WHEN NULL
CASE WHEN ISNULL(P.Photos_Cloned_From,'') = '' THEN 'http://www.toolboxbarn.com/v/vspfiles/photos/'+P.ProductCode+'-2T.jpg'
ELSE 'http://www.toolboxbarn.com/v/vspfiles/photos/'+P.Photos_Cloned_From+'-2T.jpg'
END AS image_link,
SELECT
F.Name
, F.Address
, F.InDate
, ( CASE WHEN (F.Date_Down IS NULL and F.Cod_Down = 0 )THEN 0 ELSE -1 END) as 'sn_Down'
FROM
Folders F
I am writing a stored procedure in SQL where i have a scenario that fetch all record if parameter is null or fetch matching record if parameter is not null. In this case, i always use ISNULL function like that:
table.value = ISNULL(#param,table.value)
But in this case if value is not null, it works fine, but if value is null then it fetch all record except those where table.value is null. So i searched and found a solution here answered by sII. but i don't understand the statement
#param IS NULL OR value= #param
It works fine for me but i am unable to understand? How it works? Thanks in advance for answer.
Below is my understanding about ALL IF NULL Statement.
Case 1: If the parameter #param IS NULL.
In this case the All if NULL statement becomes like this,
NULL IS NULL OR value= #param.
Here the left part of the OR statement becomes True, So records will fetch according to that part. so the query becomes,
SELECT *FROM TABLE WHERE NULL IS NULL which is same as
SELECT *FROM TABLE. So it will fetch all the records.
Case 2: If the parameter #param have a value (say value = 1)
In this case the All if NULL statement becomes like this,
1 IS NULL OR value= 1.
Here the left part of the OR statement becomes False, So records will fetch according to the right part.
So the query becomes,
SELECT *FROM TABLE WHERE value= 1.
Hope you understand Now..
I've been searching here on stackoverflow and other sources but not found a solution to this
The query below works as expected expect for when either custinfo.cust_cntct_id or custinfo.cust_corrcntct_id = '' (blank not NULL) then I get no results. Both are integer fields and if both have an integer value then I get results. I still want a value returned for either cntct_email or corrcntct_email even if custinfo.cust_cntct_id or custinfo.cust_corrcntct_id = blank
Can someone help me out in making this work? The database is PostgreSQL.
SELECT
cntct.cntct_email AS cntct_email,
corrcntct.cntct_email AS corrcntct_email
FROM
public.custinfo,
public.invchead,
public.cntct,
public.cntct corrcntct
WHERE
invchead.invchead_cust_id = custinfo.cust_id AND
cntct.cntct_id = custinfo.cust_cntct_id AND
corrcntct.cntct_id = custinfo.cust_corrcntct_id;
PostgreSQL won't actually let you test an integer field for a blank value (unless you're using a truly ancient version - 8.2 or older), so you must be using a query generator that's "helpfully" transforming '' to NULL or a tool that's ignoring errors.
Observe this, on Pg 9.2:
regress=> CREATE TABLE test ( a integer );
CREATE TABLE
regress=> insert into test (a) values (1),(2),(3);
INSERT 0 3
regress=> SELECT a FROM test WHERE a = '';
ERROR: invalid input syntax for integer: ""
LINE 1: SELECT a FROM test WHERE a = '';
If you are attempting to test for = NULL, this is not correct. You must use IS NOT NULL or IS DISTINCT FROM NULL instead. Testing for = NULL always results in NULL, which is treated as false in a WHERE clause.
Example:
regress=> insert into test (a) values (null);
INSERT 0 1
regress=> SELECT a FROM test WHERE a = NULL;
a
---
(0 rows)
regress=> SELECT a FROM test WHERE a IS NULL;
a
---
(1 row)
regress=> SELECT NULL = NULL as wrong, NULL IS NULL AS right;
wrong | right
-------+-------
| t
(1 row)
By the way, you should really be using ANSI JOIN syntax. It's more readable and it's much easier to forget to put a condition in and get a cartesian product by accident. I'd rewrite your query for identical functionality and performance but better readability as:
SELECT
cntct.cntct_email AS cntct_email,
corrcntct.cntct_email AS corrcntct_email
FROM
public.custinfo ci
INNER JOIN public.invchead
ON (invchead.invchead_cust_id = ci.cust_id)
INNER JOIN public.cntct
ON (cntct.cntct_id = ci.cust_cntct_id)
INNER JOIN public.cntct corrcntct
ON (corrcntct.cntct_id = ci.cust_corrcntct_id);
Use of table aliases usually keeps it cleaner; here I've aliased the longer name custinfo to ci for brevity.