I've got some blank values in my table, and I can't seem to catch them in an IF statement.
I've tried
IF #value = '' and if #value = NULL and neither one catches the blank values. Is there any way to test whether or not a varchar is entirely whitespace?
AHA! Turns out I was testing for null wrong. Thanks.
ltrim(rtrim(isNull(#value,''))) = ''
To compare with NULL, use the IS NULL keyword.
--Generic example:
SELECT *
FROM MY_TABLE
WHERE SOME_FIELD IS NULL;
--Instead of
SELECT *
FROM MY_TABLE
WHERE SOME_FIELD = NULL;
if length(#value) = 0 or #value is null
(LTRIM(RTRIM(#Value))=''
should do the trick.
where length(rtrim(ltrim(yourcolumnname))) = 0 OR yourcolumnname is null
I just did some testing, and found out something interesting.
I used to write my queries like so:
SELECT *
FROM TableA
WHERE Val IS NOT NULL
AND LEN(RTRIM(LTRIM(Val))) > 0
But, you don't actually need to check for null, all you need to do is check the length after trimming the value.
SELECT *
FROM TableA
WHERE LEN(RTRIM(LTRIM(Val))) > 0
This select weeds out nulls as well as any columns with just white space.
As it turns out, you don't need to trim the value because SQL Server ignores trailing whitespace, so all you actually need it this:
SELECT *
FROM TableA
WHERE LEN(Val) > 0
Rather then performing excessive string manipulation with LTRIM AND RTRIM, just search the expression for the first "non-space".
SELECT
*
FROM
[Table]
WHERE
COALESCE(PATINDEX('%[^ ]%', [Value]), 0) > 0
You may have fields with multiple spaces (' ') so you'll get better results if you trim that:
where ltrim(yourcolumnname) = ''
Related
I have a TBV function. And that function getting couple of input parameters.
CREATE FUNCTION [dbo].[fn]
(
#id NVARCHAR(50),
...
...
)
For example i want to check that #id is not null and is not whitespace.
I was tinking to do like this
SELECT * FROM [FN_Table]() WHERE
COALESCE(#Id,'') !='' AND NULLIF(#id,'') !=null AND #Id=Id
But this is a tedious way i am sure that there would be more elegant and effective way i just newbbe in SQL and do not know best practices.
If you want id to be not null or white space, you can use ltrim():
where ltrim(#id) <> ''
This does the NULL check as well, implicitly.
I'm not sure why you have a comparison to zero. Based on your question this is not necessary. If you are passing in numbers, you should not be using a string type.
Try this, Check with ISNULL and then Get BlankSpace Character Index
SELECT
CASE WHEN ISNULL(#ID,'')='' THEN 1
WHEN CHARINDEX(' ',#ID) >0 THEN 1
ELSE 0
END
I currently have a table Telephone it has entries like the following:
9073456789101
+773456789101
0773456789101
What I want to do is remove only the 9 from the start of all the entries that have a 9 there but leave the others as they are.
any help would be greatly appreciated.
While all other answer are probably also working, I'd suggest to try and use STUFF function to easily replace a part of the string.
UPDATE Telephone
SET number = STUFF(number,1,1,'')
WHERE number LIKE '9%'
SQLFiddle DEMO
Here is the code and a SQLFiddle
SELECT CASE
WHEN substring(telephone_number, 1, 1) <> '9'
THEN telephone_number
ELSE substring(telephone_number, 2, LEN(telephone_number))
END
FROM Telephone
Update Telephone set number = RIGHT(number,LEN(number)-1) WHERE number LIKE '9%';
I recently solved a similar problem with a combination of RIGHT(), LEN() & PATINDEX(). PATINDEX will return the integer 1 when it finds a 9 as the first character and 0 otherwise. This method allows all records to be returned at once without a CASE WHEN statement.
SELECT
RIGHT(number, LEN(number) - PATINDEX('9%', number))
FROM Telephone
UPDATE dbo.Telephone
SET column_name = SUBSTRING(column_name, 2, 255)
WHERE column_name LIKE '9%';
Stuff is a great function for this. However, using it with an update statement with a where clause is great, but what if I was doing an insert, and I needed all of the rows inserted in one pass. The below will remove the first character if it is a period, does not use the slower case statement, and converts nulls to an empty string.
DECLARE #Attachment varchar(6) = '.GIF',
#Attachment2 varchar(6)
SELECT
#Attachment2 = ISNULL(ISNULL(NULLIF(LEFT(#Attachment, 1), '.'), '') + STUFF(#Attachment, 1, 1, ''), '')
SELECT
#Attachment2
DECLARE #STR nvarchar(200) = 'TEST'
SET #STR = STUFF(#STR,1,1,'')
PRINT #STR
Result will be "EST"
You can use replace in select statement instead of where or update
SELECT REPLACE(REPLACE('_'+number,'_9',''),'_','') FROM #tbl
Quite simply, which of the following methods is better in a WHERE clause to retrieve records where the FIELD_NAME is NOT NULL and NOT Empty
WHERE DATALENGTH(FIELD_NAME) > 0
or
WHERE ISNULL(FIELD_NAME, '') <> ''
Update
I have been informed that the first method gives spurious results for some types of fields... Agree?
Firstly,
select *
from table
where column <> ''
will give exactly the same results as
select *
from table
where isnull(column, '') <> ''
because records where the condition is UNKNOWN rather than FALSE will still be filtered out. I would generally go with the first option.
DATALENGTH counts trailing spaces, which a comparison with '' does not. It is up to you whether you want ' ' to compare unequal to ''. If you do, you need DATALENGTH. If you don't, simply compare with ''.
Note that for TEXT/NTEXT types, comparisons are not supported, but DATALENGTH is.
ISNULL is the best approach instead of DATALENGTH.
I would use
WHERE ISNULL(FIELD_NAME, '') <> ''
One issue that might come up is that a record with a space in it would not be returned. Are you looking for records like that?
I'm not sure about unexpected results from DATALENGTH. I would use the ISNULL method so that SQL Server doesn't need to spend time calculating the length of the record being compared. I don't know the performance difference between the two, just a gut feeling.
if your "not empty" condition encompasses spaces then i would use the nullif
select case when nullif(' ', '') is null then 'y' else 'n' end
y
declare #d varchar(50)
set #d = null
select case when nullif(#d, '') is null then 'y' else 'n' end
y
I would use one of the following:
where coalesce(field_name, '') <> ''
or
where field_name <> '' or field_name is not null
or
where field_name <> ''
The first is standard SQL (coalesce() is standard, isnull() is not). The last is not the most obvious, but NULL will fail the comparison and it allows the use of indexes.
RTRIM(LTRIM(ISNULL(FIELD_NAME, ''))) <> '' will handle spaces and NULLS
I am having trouble with some sql. When I run the following query:
Select * from teleapp;
I get TONS of results. Resulst which include a column (called cashwithappyn) that has TONS of empty or null data cells. (They look empty and don't say null)
The column info is:
ColumnName ID Null? Data Type Histogram Num Distinct Num Nulls Density
CASHWITHAPPYN 54 Y VARCHAR2(1 Byte) Frequency 2 56895 0
When I try to run the following query:
Select * from teleapp where cashwithappyn = null;
or
Select * from teleapp where cashwithappyn = '';
or
Select * from teleapp where cashwithappyn not like '';
or
Select * from teleapp where cashwithappyn not in ('Y','N');
or ANY type of combination, I cannot seem to get all of the rows with nothing in cashwithappyn.
Any ideas? Please help, this is the last part of a project that I was assigned to do and I just need to figure this out.
Thanks.
Maybe the column contains blanks. In that case you can do
WHERE TRIM(CASHWITHAPYYN) IS NULL
TRIM removes all blanks before and after and if nothing is left anymore the value becomes NULL
e.g.
TRIM(' ') IS NULL -- one blank removed = true
TRIM(NULL) IS NULL -- true
Also NULL cannot be compared with = NULL but must be phrased IS NULL. NULL is not a value as such and that is why the comparison never works.
You need to use IS NULL
Select * from teleapp where cashwithappyn is null;
Logical test expressions (=, Not In, Like etc) with null result in a false so all of the following result in false
1 = NULL
1 <> NULL
NULL = NULL
NULL <> NULL
NULL NOT IN ('a','b')
NULL Not Like NULL
Additionally in oracle the zero length string is null so NOT LIKE '' will never return any rows
You'll need to use either is null, is not null or Coalesce
A co-worker and I did a bunch of research, here's what we came up with that will work. Any ideas why this works but not the others?
Select * from teleapp where nvl(cashwithappyn,'U') = 'U';
Is there an equivalent to IsDate or IsNumeric for uniqueidentifier (SQL Server)?
Or is there anything equivalent to (C#) TryParse?
Otherwise I'll have to write my own function, but I want to make sure I'm not reinventing the wheel.
The scenario I'm trying to cover is the following:
SELECT something FROM table WHERE IsUniqueidentifier(column) = 1
SQL Server 2012 makes this all much easier with TRY_CONVERT(UNIQUEIDENTIFIER, expression)
SELECT something
FROM your_table
WHERE TRY_CONVERT(UNIQUEIDENTIFIER, your_column) IS NOT NULL;
For prior versions of SQL Server, the existing answers miss a few points that mean they may either not match strings that SQL Server will in fact cast to UNIQUEIDENTIFIER without complaint or may still end up causing invalid cast errors.
SQL Server accepts GUIDs either wrapped in {} or without this.
Additionally it ignores extraneous characters at the end of the string. Both SELECT CAST('{5D944516-98E6-44C5-849F-9C277833C01B}ssssssssss' as uniqueidentifier) and SELECT CAST('5D944516-98E6-44C5-849F-9C277833C01BXXXXXXXXXXXXXXXXXXXXXXXXXXXXX' as uniqueidentifier) succeed for instance.
Under most default collations the LIKE '[a-zA-Z0-9]' will end up matching characters such as À or Ë
Finally if casting rows in a result to uniqueidentifier it is important to put the cast attempt in a case expression as the cast may occur before the rows are filtered by the WHERE.
So (borrowing #r0d30b0y's idea) a slightly more robust version might be
;WITH T(C)
AS (SELECT '5D944516-98E6-44C5-849F-9C277833C01B'
UNION ALL
SELECT '{5D944516-98E6-44C5-849F-9C277833C01B}'
UNION ALL
SELECT '5D944516-98E6-44C5-849F-9C277833C01BXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
UNION ALL
SELECT '{5D944516-98E6-44C5-849F-9C277833C01B}ssssssssss'
UNION ALL
SELECT 'ÀD944516-98E6-44C5-849F-9C277833C01B'
UNION ALL
SELECT 'fish')
SELECT CASE
WHEN C LIKE expression + '%'
OR C LIKE '{' + expression + '}%' THEN CAST(C AS UNIQUEIDENTIFIER)
END
FROM T
CROSS APPLY (SELECT REPLACE('00000000-0000-0000-0000-000000000000', '0', '[0-9a-fA-F]') COLLATE Latin1_General_BIN) C2(expression)
WHERE C LIKE expression + '%'
OR C LIKE '{' + expression + '}%'
Not mine, found this online... thought i'd share.
SELECT 1 WHERE #StringToCompare LIKE
REPLACE('00000000-0000-0000-0000-000000000000', '0', '[0-9a-fA-F]');
SELECT something
FROM table1
WHERE column1 LIKE '[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]-[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]-[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]-[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]-[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]';
UPDATE:
...but I much prefer the approach in the answer by #r0d30b0y:
SELECT something
FROM table1
WHERE column1 LIKE REPLACE('00000000-0000-0000-0000-000000000000', '0', '[0-9a-fA-F]');
I am not aware of anything that you could use "out of the box" - you'll have to write this on your own, I'm afraid.
If you can: try to write this inside a C# library and deploy it into SQL Server as a SQL-CLR assembly - then you could use things like Guid.TryParse() which is certainly much easier to use than anything in T-SQL....
A variant of r0d30b0y answer is to use PATINDEX to find within a string...
PATINDEX('%'+REPLACE('00000000-0000-0000-0000-000000000000', '0', '[0-9a-fA-F]')+'%',#StringToCompare) > 0
Had to use to find Guids within a URL string..
HTH
Dave
Like to keep it simple. A GUID has four - in it even, if is just a string
WHERE column like '%-%-%-%-%'
Though an older post, just a thought for a quick test ...
SELECT [A].[INPUT],
CAST([A].[INPUT] AS [UNIQUEIDENTIFIER])
FROM (
SELECT '5D944516-98E6-44C5-849F-9C277833C01B' Collate Latin1_General_100_BIN AS [INPUT]
UNION ALL
SELECT '{5D944516-98E6-44C5-849F-9C277833C01B}'
UNION ALL
SELECT '5D944516-98E6-44C5-849F-9C277833C01BXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
UNION ALL
SELECT '{5D944516-98E6-44C5-849F-9C277833C01B}ssssssssss'
UNION ALL
SELECT 'ÀD944516-98E6-44C5-849F-9C277833C01B'
UNION ALL
SELECT 'fish'
) [A]
WHERE PATINDEX('[^0-9A-F-{}]%', [A].[INPUT]) = 0
This is a function based on the concept of some earlier comments. This function is very fast.
CREATE FUNCTION [dbo].[IsGuid] (#input varchar(50))
RETURNS bit AS
BEGIN
RETURN
case when #input like '[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]-[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]-[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]-[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]-[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]'
then 1 else 0 end
END
GO
/*
Usage:
select [dbo].[IsGuid]('123') -- Returns 0
select [dbo].[IsGuid]('ebd8aebd-7ea3-439d-a7bc-e009dee0eae0') -- Returns 1
select * from SomeTable where dbo.IsGuid(TableField) = 0 -- Returns table with all non convertable items!
*/
DECLARE #guid_string nvarchar(256) = 'ACE79678-61D1-46E6-93EC-893AD559CC78'
SELECT
CASE WHEN #guid_string LIKE '________-____-____-____-____________'
THEN CONVERT(uniqueidentifier, #guid_string)
ELSE NULL
END
You can write your own UDF. This is a simple approximation to avoid the use of a SQL-CLR assembly.
CREATE FUNCTION dbo.isuniqueidentifier (#ui varchar(50))
RETURNS bit AS
BEGIN
RETURN case when
substring(#ui,9,1)='-' and
substring(#ui,14,1)='-' and
substring(#ui,19,1)='-' and
substring(#ui,24,1)='-' and
len(#ui) = 36 then 1 else 0 end
END
GO
You can then improve it to check if it´s just about HEX values.
I use :
ISNULL(convert(nvarchar(50), userID), 'NULL') = 'NULL'
I had some Test users that were generated with AutoFixture, which uses GUIDs by default for generated fields. My FirstName fields for the users that I need to delete are GUIDs or uniqueidentifiers. That's how I ended up here.
I was able to cobble together some of your answers into this.
SELECT UserId FROM [Membership].[UserInfo] Where TRY_CONVERT(uniqueidentifier, FirstName) is not null
Use RLIKE for MYSQL
SELECT 1 WHERE #StringToCompare
RLIKE REPLACE('00000000-0000-0000-0000-000000000000', '0', '[0-9a-fA-F]');
In a simplest scenario. When you sure that given string can`t contain 4 '-' signs.
SELECT * FROM City WHERE Name LIKE('%-%-%-%-%')
In BigQuery you can use
SELECT *
FROM table
WHERE
REGEXP_CONTAINS(uuid, REPLACE('^00000000-0000-0000-0000-000000000000$', '0', '[0-9a-fA-F]'))