tbl_LoanSummary has Sample_Number column. I have to check if Sample_Number column is not null the return 'Y' otherwise return return 'N' from below select statement.
select a.Br_Loan_No ,a.Br_LookupKey, //return IsNull(s.Sample_Number) ='N' or 'Y'
from dbo.tbl_Br a left outer join dbo.tbl_LoanSummary s
on s.Loan_no = a.Br_Loan_No order by a.Br_Loan_No
How to do this?
You can use the case expression for this...
select a.Br_Loan_No,
a.Br_LookupKey,
CASE WHEN s.Sample_Number IS NULL THEN 'N' ELSE 'Y' END AS [HasSample]
from dbo.tbl_Br a left outer join dbo.tbl_LoanSummary s
on s.Loan_no = a.Br_Loan_No order by a.Br_Loan_No
In Oracle, you could also use
select NVL(s.Sample_Number, 'N')
to return N in case of null value
(of course you still need something to have Y in case of not null.)
You'll want to use a CASE expression. It's like an embedded if-statement or switch-statement from traditional programming languages.
SELECT a.Br_Loan_No,
a.Br_LookupKey
CASE
WHEN s.Sample_Number IS NULL THEN 'N'
ELSE 'Y'
END AS sample_number_is_not_null
FROM dbo.tbl_Br a
LEFT JOIN dbo.tbl_LoanSummary s
ON s.Loan_no = a.Br_Loan_No
ORDER BY a.Br_Loan_no
Note that you are creating a computed column here, rather than selecting the raw value of an existing column. It's generally required that you give this column a name, thus the use of the AS sample_number_is_not_null.
There are two forms of the CASE expression. One lets you compare a column or value against several choices. It is like using an implicit equals:
CASE foo
WHEN 3 THEN 'foo is 3!'
WHEN 4 THEN 'foo is 4!'
ELSE 'foo is not 3 or 4'
END
The other form, in the example at the top, lets you use arbitrary expressions in each WHEN clause. It should be noted that each WHEN clause is evaluated in order and the first one to match is the one whose THEN is used as the result. If none of the WHENs match, then the result in the ELSE is used.
Related
I wanted to put 'No record' on the column instead of NULL if the datediff function returns a null value.
SELECT concat(e.firstname ,e.lastname) as Fullname,c.shiftcode as Shift, cast(c.datecheckinout as date) Date,datename(month, c.datecheckinout) as RecordMonth,c.timein , c.timeout,
CAST(
CASE
WHEN (datediff(HOUR,c.timein,c.timeout) IS NULL)
THEN 'No record'
END
), FROM tblCheckInOutDetail c RIGHT JOIN tblEmployee e on e.IdEmployee = c.IdEmployee WHERE e.IdEmployee = 55
So far this code only throws Incorrect syntax near 'CAST', expected 'AS'. but I don't know what data type should I put in the CAST parameter , since if there's a record it will show the datetime .
You need to convert the number value to a string. For this, you can use coalesce():
SELECT concat(e.firstname ,e.lastname) as Fullname,c.shiftcode as Shift, cast(c.datecheckinout as date) Date,datename(month, c.datecheckinout) as RecordMonth,c.timein , c.timeout,
COALESCE(CAST(datediff(HOUR, c.timein, c.timeout) AS VARCHAR(255)), 'No record')
FROM tblEmployee e LEFT JOIN
tblCheckInOutDetail c
ON e.IdEmployee = c.IdEmployee
WHERE e.IdEmployee = 55;
Note: I switched the RIGHT JOIN to a LEFT JOIN. They are equivalent logically. But most people find it much easier to follow the logic of the LEFT JOIN, because the table that defines the rows is the first table being read in the FROM clause.
Strictly answering question (though I don't understand why you need a CASE expression if you have working versions of the query), you can easily translate this to a CASE expression:
ISNULL(CAST(datediff(HOUR,c.timein,c.timeout) as varchar),'No Record')
ISNULL really is just nice, convenient shorthand for CASE WHEN a IS NOT NULL THEN a ELSE b END, so:
CASE WHEN DATEDIFF(HOUR, c.timein, c.timeout) IS NOT NULL
THEN CAST(datediff(HOUR,c.timein,c.timeout) as varchar(11))
ELSE 'No Record' END
As you can see, a downside is that if you really really really want a CASE expression, you have to repeat at least the DATEDIFF to cover both the case where the outer row doesn't exist and the case where the outer row exists but one of the values is NULL.
Also note that you should always specify a length for variable types like varchar, even in cases where you think you're safe with the default.
I don't know if this is the correct option or usage.
but this works for me :
ISNULL(CAST(datediff(HOUR,c.timein,c.timeout) as varchar),'No Record')
But can you guys show me how to do this using case expression?
I have a column in table which is having single/multiple value. I have to convert it yes/no based on condition.
example:
rendition_type_sys
distribution
uploaded, distribution
uploaded
single
I need to change the value based on condition. If column having distribution then value should convert as 'Yes' otherwise 'No'
Final Output:
rendition_type_sys
Yes
Yes
No
No
I tried one case statement but that is working for single value not multiple value-
case when ren.rendition_type__sys='distribution' then 'Yes' else 'No' end as rendition_type__sys
First, you should fix your data model so you are not storing multiple values in a string.
In the meantime, like should do what you want. For your example:
(case when ren.rendition_type__sys like '%distribution%'
then 'Yes' else 'No'
end) as rendition_type__sys
Note: In case "distribution" is part of an element name and you don't want that, you can check for delimiters. In Standard SQL, this would be:
(case when ', ' || ren.rendition_type__sys || ', ' like '%, distribution, %'
then 'Yes' else 'No'
end) as rendition_type__sys
The string concatenation operator may vary depending on the database you are using.
This below code would work assuming distribution is not part of any other discrete value; here is the code in a sample form:
WITH rt AS (
SELECT 'distribution' AS rendition_type_sys
UNION SELECT 'uploaded, distribution'
UNION SELECT 'uploaded'
UNION SELECT 'single'
)
SELECT CASE WHEN rt.rendition_type_sys LIKE 'distribution' THEN 'Yes' ELSE 'No' END AS Col
FROM rt
You might consider adding a table with for these "tags" so that they are discrete.
I have an SQL query where the case expression is not working because I am getting the NULL value.
Any idea how to fix this?
select
td.reportEndDate,
CASE td.originalLinearAirDate
WHEN NULL THEN '12345678'
END As originalLinearAirDate
from
FROM DBA.Telecast td
where id = 2
order by
td.reportEndDate,
originalLinearAirDate;
You can use isnull
select
td.reportEndDate,
CASE WHEN td.originalLinearAirDate IS NULL THEN '19000101'
ELSE td.originalLinearAirDate
END As originalLinearAirDate
from
FROM DBA.Telecast td
where id = 2
order by
td.reportEndDate,
originalLinearAirDate;
You can use COALESCE() :
SELECT td.reportEndDate,
COALESCE(td.originalLinearAirDate, '12345678') AS originalLinearAirDate -- Use default date instead of '12345678'
FROM DBA.Telecast td
WHERE id = 2
ORDER BY td.reportEndDate, originalLinearAirDate;
In your case expression you didn't specified ELSE part hence you got NULL.
However, case expression will only return one type. So, you should check code or do necessary conversation.
The problem is the NULL comparison. The comparison is never true, even when used from comparison in a CASE expression.
If you wanted to do this using CASE, then you need to use IS NULL:
(CASE WHEN td.originalLinearAirDate IS NULL
THEN '12345678'
END) As originalLinearAirDate
If you want to return the original value in this case, you need an ELSE:
(CASE WHEN td.originalLinearAirDate IS NULL
THEN '12345678'
ELSE td.originalLinearAirDate
END) As originalLinearAirDate
Note that this will return an error if the column is really a DATE, because '12345678' cannot be converted to a date.
This version is better expressed using COALESCE():
COALESCE(td.originalLinearAirDate, '12345678')
I'm struggling to understand how to check for a null value in a progress case expression. I want to see if a column exists and use that, if not use the fallback column. For example, William in first name would be over written by Bill in fn.special-char.
I've got the following query:
SELECT
"PUB"."NAME"."LAST-NAME" as LastName,
CASE fn."SPECIAL-CHAR"
WHEN is null THEN "PUB"."NAME"."FIRST-NAME"
ELSE fn."SPECIAL-CHAR"
END as FirstName
FROM "PUB"."NAME"
LEFT OUTER JOIN "PUB"."DAT-DATA" fn on "PUB"."NAME"."NAME-ID" = fn."DAT-SRC-ID" and 11 = fn."FLD-FIELD-ID"
When I run the query I get:
ORBC Progress OpenEdge Wire Protocol driver][OPENEDGE]Syntax error SQL statement at or about "is null then "PUB"."NAME"."FIRST-" (10713)
If I do a select * I see everything. It just doesn't like the null part. I can also change the when is null to when 'bob' and it works.
Is there something different I need to do to use a null value in a progress db query?
The shorthand variation of the case statement (case expression when value then result ...) is a shorthand for a series of equality conditions between the expression and the given values. null, however, is not a value - it's the lack thereof, and must be evaluated explicitly with the is operator, as you tried to do. In order to do this properly, however, you need to use a slightly longer variation of the case syntax - case when condition then result ...:
SELECT
"PUB"."NAME"."LAST-NAME" as LastName,
CASE WHEN fn."SPECIAL-CHAR" IS NULL THEN "PUB"."NAME"."FIRST-NAME"
ELSE fn."SPECIAL-CHAR"
END as FirstName
FROM "PUB"."NAME"
LEFT OUTER JOIN "PUB"."DAT-DATA" fn on "PUB"."NAME"."NAME-ID" = fn."DAT-SRC-ID" and 11 = fn."FLD-FIELD-ID"
Instead of CASE you can use IFNULL function in Progress 4GL.
SELECT
"PUB"."NAME"."LAST-NAME" as LastName,
IFNULL(fn."SPECIAL-CHAR", "PUB"."NAME"."FIRST-NAME") as FirstName
FROM "PUB"."NAME"
LEFT OUTER JOIN "PUB"."DAT-DATA" fn on "PUB"."NAME"."NAME-ID" = fn."DAT-SRC-ID" and 11 = fn."FLD-FIELD-ID"
I can't believe I'm having so much trouble with this.
Using this statement:
USE XXXX
SELECT
ID, DESCRIPTION, STATUS
FROM
PART
WHERE
PART.ID LIKE 'PCH%'
AND PART.DESCRIPTION NOT LIKE '%OBSOLETE%'
AND PART.STATUS = 'O'
I get a table with 34 entries, each of them containing O in PART.STATUS.
What I actually want to say is, only show me the values which do NOT have a status of O. I know there are other ways around this. values that are not O should be null, but I'm annoyed that I can't figure out how the 'not equal' statement works. When I switch the last line to:
AND PART.STATUS <> 'O'
OR
AND PART.STATUS != 'O'
I get an empty table returned.
If I use the line
AND PART.STATUS IS NULL
I get the table I'm looking for.
What am I misunderstanding about the use of 'not equal statements'?
The problem is 3 valued predicate logic. When at least one side of predicate is NULL the result of predicate is UNKNOWN(no matter you use = or <> or > or <, ...), but WHERE clause only returns rows where predicate evaluates to TRUE. So our job is to make predicate to evaluate to TRUE when PART.STATUS IS NULL. This is done by adding additional check on NULL like:
USE XXXX
SELECT ID, DESCRIPTION,STATUS
FROM PART
WHERE
PART.ID LIKE 'PCH%'
AND PART.DESCRIPTION NOT LIKE '%OBSOLETE%'
AND (PART.STATUS <> 'O' OR PART.STATUS IS NULL)
Here is a little example. Imagine this is your table and you are issuing your statement WHERE PART.STATUS <> 'O'
PART(STATUS)
'A'
'O'
NULL
It evaluates to:
WHERE 'A' <> 'O' --TRUE
WHERE 'O' <> 'O' --FALSE
WHERE NULL <> 'O'--UNKNOWN
Since WHERE clause returns only rows where result of predicate is TRUE, you will get only 'A' here.
the issue here is with the nullvalue since every logical comparation against it would return false for example
PART.STATUS = NULL-- Would be false
PART.STATUS <> NULL-- would also return false
so you should do your comparison like
AND (PART.STATUS <> 'O' OR PART.STATUS IS NULL)
The part you're missing is that NULL is not a value, but the absence of it. A NULL means that the value in that field is either inexistent or unknown. That's why you cant' directly compare a value to a NULL. As stated in other answers, you have to use PART.STATUS IS NULL. Another option would be to use the ISNULL function, wich will test a value for NULL and, if it is, will return whatever value you specify on the second parameter. E.g.
USE XXXX
SELECT ID, DESCRIPTION,STATUS
FROM PART
WHERE
PART.ID LIKE 'PCH%'
AND PART.DESCRIPTION NOT LIKE '%OBSOLETE%'
AND ISNULL(PART.STATUS, '') <> 'O'
Check the documentation for NULL in Sql Server and the ISNULL function. Also, this question could be of use.
USE XXXX
SELECT ID, DESCRIPTION,STATUS
FROM PART
WHERE
PART.ID LIKE 'PCH%'
AND PART.DESCRIPTION NOT LIKE '%OBSOLETE%'
OR PART.STATUS != 'O'
Maybe your misunderstanding is probably about the NULL concept. NULL is not an empty string neither different from 'O', it's just NULL.
That's why you have to use
AND PART.STATUS IS NULL
or
AND isnull(PART.STATUS, '') <> 'O'
It is important to remember how NULL is treated in a database. It isn't a value at all!
No operator (>,<,=.. etc) less (is) used will ever return rows with NULL.
writing in SQL "where column = NULL" is like saying "give me all rows where the value isn't a value
Null values can't be compared with equals(=) or not equals operators. Try the below:
USE XXXX
SELECT ID, DESCRIPTION,STATUS FROM PART WHERE
PART.ID LIKE 'PCH%'
AND PART.DESCRIPTION NOT LIKE '%OBSOLETE%'
AND ISNULL(PART.STATUS, '') <> 'O'