Is there anyway that I can change column name through THEN clause in CASE STATEMENT. This is how my code looks but it is not working.
SELECT
CASE
WHEN #IDWeeklySpecial = '107'
THEN
CASE
WHEN ISNULL(v.blnLeftHandDrive, 0) = 1
THEN [HANDEDNESS] = 'LHD'
ELSE [HANDEDNESS] = 'RHD'
ELSE
CASE
WHEN ISNULL(v.blnLeftHandDrive, 0) = 1
THEN STEERING = 'LHD'
ELSE STEERING = 'RHD'
END
END
I want this result
My Ideal Result
Is this achievable? If so how?
No, it's not possible... if you are asking about dynamically modifying the column name in the resultset.
The CASE expression returns a value. To a specify the column name in the resultset, assign an alias.
SELECT CASE ... END AS mycolname
, ...
FROM ...
The column name is determined when the statement is parsed and prepared. The execution of the statement cannot modify the column name.
(It's possible I didn't understand the question. It's not clear what OP is tying to achieve.)
case is an expression. You can name the column before or after an expression, but not in the middle.
Also, a SQL statement needs to return a fixed set of columns, including the column name.
So, you cannot do what you want with a simple SQL statement. You could use dynamic SQL:
declare #sql nvarchar(max);
set #sql = '
SELECT (CASE WHEN COALESCE(v.blnLeftHandDrive, 0) = 1
THEN 'LHD'
ELSE 'RHD'
END) as [columnname]
. . . ';
set #sql = replace(#sql, '[columnname]',
(case when #IDWeeklySpecial = '107' then 'HANDEDNESS' else 'STEERING' end)
);
exec sp_executesql #sql;
Note that the . . . is for the rest of your SQL query.
I can't digest your select statement, but assume its inline case
SELECT item_name = CASE WHEN item_name = 'sometext' THEN item_id ELSE item_name END AS MyColumnName
It is not possible to assign differing column names in your query, because all vertical data values in the result set belong to the same column.
If you are just trying to alias a column name while using the CASE expression, ensure that the AS is used after the END keyword. Others have mentioned this, but it was the problem in my case. Changed it to something like this and it worked:
CASE
WHEN table1.Name LIKE '%John%' THEN 'Some John Person'
WHEN table1.Name <> 'NULL' THEN table1.Name
ELSE 'Nobody'
END AS NewAliasColumnName
Related
We have a table LogicalTableSharing as follows:
For a specific requirement, we need to take PhysicalCompany of each TableCode into a variable.
We tried a case-based query as follows:
declare #tablecode varchar(50)
declare #inputcompany varchar(50)
declare #query nvarchar(2500)
set #inputcompany= 91
set #query = '
select '''+#inputcompany+''' AS inputcompany,
CASE WHEN lts.TableCode = ''tsctm005'' THEN lts.PhysicalCompany ELSE NULL END as tsctm005_company,
CASE WHEN lts.TableCode = ''tccom000'' THEN lts.PhysicalCompany ELSE NULL END as tccom000_company
from LogicalTableSharing lts
where lts.LogicalCompany = '''+#inputcompany+'''
'
EXEC sp_executesql #query
which obviously gives the result as
The desired output is
What is the right approach?
Try subqueries in a FROM-less SELECT. For performance you want an index on (logicalcompany, tablecode) (or the other way round depending on which is more selective).
SELECT #inputcompany inputcompany,
(SELECT TOP 1
physicalcompany
WHERE logicalcompany = #inputcompany
AND tablecode = 'tsctm005'
ORDER BY <some criteria>) tsctm005_company,
(SELECT TOP 1
physicalcompany
WHERE logicalcompany = #inputcompany
AND tablecode = 'tccom000'
ORDER BY <some criteria>) tccom000_company;
You should find <some criteria> to order by in case of multiple possible rows to decide which one takes precedence. Unless you just want a random one possibly each time you run the query another one, that is.
I have below dynamic WHERE condition in XML mapping which is working fine:
WHERE
IncomingFlightId=#{flightId}
<if test="screenFunction == 'MAIL'.toString()">
and ContentCode = 'M'
</if>
<if test="screenFunction == 'CARGO'.toString()">
and ContentCode Not IN('M')
</if>
order by ContentCode ASC
I'm trying to run below query in a IDE but unfortunately its not working.
Can anybody please explain what i'm doing wrong?
WHERE
IncomingFlightId = 2568648
AND (IF 'MAIL' = 'MAIL'
BEGIN
SELECT 'and ContentCode = "M"'
END ELSE BEGIN
SELECT 'and ContentCode Not IN("M")'
END)
order by ContentCode ASC
You can't use IF in straight up SQL statement, use CASE WHEN test THEN returniftrue ELSE valueiffalse END instead (if you have to use conditional logic)
That said, it's probably avoidable if you do something like this:
WHERE
(somecolumn = 'MAIL' AND ContentCode = 'M') OR
(somecolumn <> 'MAIL' and ContentCode <> 'M')
Example of conditional logic in a straight SQL:
SELECT * FROM table
WHERE
CASE WHEN col > 0 THEN 1 ELSE 0 END = 1
Case when runs a test and returns a value. You always have to compare the return value to something else. You can't do something that doesn't return a value.
It's kinda dumb here though, because anything you can express in the truth of a case when, can be more simply and readably expressed in the truth of a where clause directly..
SELECT * FROM table
WHERE
CASE WHEN type = 'x'
THEN (SELECT count(*) FROM x)
ELSE (SELECT count(*) FROM y)
END = 1
Versus
SELECT * FROM table
WHERE
(type = 'x' AND (SELECT count(*) FROM x) = 1) OR
type <> 'x' AND (SELECT count(*) FROM y) = 1)
It's useful for things like this though:
SELECT
bustourname,
SUM(CASE WHEN age > 60 THEN 1 ELSE 0 END) as count_of_old_people
FROM table
GROUP BY bustourname
If you're looking to write a stored procedure that conditionally builds an SQL, then sure, you can do that...
DECLARE #sql VARCAHR(max) = 'SELECT * FROM TABLE WHERE';
IF blah SET #sql = CONCAT(#sql, 'somecolumn = 1')
IF otherblah SET #sql = CONCAT(#sql, 'othercolumn = 1')
EXEC #sql...
But this is only in a stored procedure or procedure-like sql script where it builds a string that looks like an SQL, and then executes it dynamically. You cannot use IF in a plain SELECT statement
You are running the query which (beside it is syntactically incorrect SQL) has nothing to do with query generated and used by mybatis.
You need to understand how if in mybatis mapper works.
if element evaluates before the query is executed at the stage of generation of the SQL query text. If the value of the test is true the content of if element is included into the resulting query. In your case depending on the screenFunction parameter passed to mybatis mapper method one of three conditions are generated.
If value of screenFunction is MAIL then:
WHERE
IncomingFlightId=#{flightId}
and ContentCode = 'M'
order by ContentCode ASC
If value of screenFunction is CARGO then:
WHERE
IncomingFlightId=#{flightId}
and ContentCode Not IN('M')
order by ContentCode ASC
Otherwise (if value of screenFunction is not MAIL and is not CARGO):
WHERE
IncomingFlightId=#{flightId}
order by ContentCode ASC
Only after the query text is generated it is executed via JDBC against the database.
So if you want to run the query manually you need to try one of these queries.
One thing that you may want to do to make it easier is to enable logging of SQL queries and parameters passed to them so you can more easily rerun them.
Facing problem for generating SQL Server Query
In the Following query dynamic conditions are added to check whether value is null or not
Select *
From tblEmployees
where EmployeeName = Case
When #EmployeeName Is Not Null
Then #EmployeeName
Else EmployeeName
End
But I need to add IN () Conditions and the parameter with in the IN () could be null or blank also ,if the parameter /string which is passed to the IN condition is blank then i donot want to add that condition in the query.
So how can i Achieve this.A helping hand will be very useful for me.
Thanks and Regards,
D.Mahesh
Depending on value of your parameter (blank of not), you can create SQL string accordingly.
DECLARE #sqlCommand VARCHAR(1000)
IF(ISNULL(#YourParameter,'')='')
#sqlCommand = 'your query goes here'
ELSE
#sqlCommand = 'your query goes here'
and then, run it using dynamic query execution
EXEC (#sqlCommand)
If not dynamic query then,
SELECT ....
FROM ....
WHERE CASE WHEN ISNULL(#YourParameter,'')='' THEN '' ELSE EmployeeName END IN (ISNULL(#YourParameter,''))
See if this works...
I think the Dynamic query is the best solution, however you could put the "IS NULL" and "IS BLANK" condition in OR with your IN clause.
Something like that
Select *
From tblEmployees
where #EmployeeName is null or EmployeeName in (#EmployeeName)
When #EmployeeName is null, your IN clause will be ignored
If i get this right you have #EmployeeName = 'Name1,Name2,Name3' and you want to get the employees that is named Name1 or Name2 or Name3, also the variable #EmployeeName can be null or contain an empty string.
Instead of using IN you can split the string #EmployeeName on , and store it in a table variable or temporary table. Then you can use that table in a join against tblEmployees to get the rows you need.
There are a lot of posts in S.O. about how to split a string. Here is one recent variant.
Group by sql query on comma joined column
This will work for SQL Server 2005 or later.
declare #EmployeeName varchar(100) = 'Name2,Name3,Name5'
-- Null or empty will have a comma
set #EmployeeName = coalesce(#EmployeeName, '') + ','
-- cteNames splits the string to rows
;with cteNames
as
(
select
left(#EmployeeName, charindex(',', #EmployeeName)-1) as Name,
right(#EmployeeName, len(#EmployeeName)-charindex(',', #EmployeeName)) as EmployeeName
union all
select
left(EmployeeName, charindex(',', EmployeeName)-1) as Name,
right(EmployeeName, len(EmployeeName)-charindex(',', EmployeeName)) as EmployeeName
from cteNames
where charindex(',', EmployeeName) > 1
)
select E.*
from tblEmployees as E
inner join cteNames as N
on E.Name = N.Name or
#EmployeeName = ','
-- #EmployeeName = ',' will give you all names when #EmployeeName is null of empty
How do I evaluate a character expression to resolve to a valid column name in a SELECT statement that would return column row values? Eg valid column name = Customer_1 == 'Customer_'+'1'
You need to use dynamic SQL. An example
DECLARE #DynSQL nvarchar(max)
DECLARE #Suffix int = 1
SET #DynSQL = N'SELECT Customer_' + CAST(#Suffix as nvarchar(10)) +
N' FROM YourTable WHERE foo = #foo'
EXEC sp_executesql #DynSQL, N'#foo int', #foo=1
As always with dynamic SQL you need to consider SQL injection if any of the inputs to the process will be user supplied.
How do I evaluate a character expression to resolve to a valid column name in a SELECT statement that would return column row values? Eg valid column name = Customer_1 == 'Customer_'+'1'
You're probably doing something wrong if you need to do this, but if you have to: build the column names as rows and then pivot.
I want to include column in where clause depending on the condition.
e.g
select * From emp
where id=7,
and if(code is not null) then code=8;
how can i do this in sql server
If I understand you correct, you could make use of COALESCE.
COALESCE()
Returns the first nonnull expression
among its arguments.
SQL Statement
SELECT *
FROM emp
WHERE id=7
AND code = COALESCE(#code, code)
If code is a column rather than a variable the query in your question would be rewritten as follows.
SELECT *
FROM emp
WHERE id=7 AND (code IS NULL OR code=8)
You'll probably have to create a query dynamically, as a string, and then use the Execute method to actually execute it. This approach has some potentially optimization issues, but it's commonly done. You might wan to Google T-SQL Dynamic Query, or something like that.
Also use this in case of Null value in #var1.
Select * from ABC where Column1 = isNull(#var1, Column1)
here is the example:
declare #SQL varchar(500)
declare #var1 int
set int = 1
set #SQL = 'Select * from ABC Where 1 = 1'
if(#var1 = 1)
set #SQL + #SQL ' And column1 = ' #var1
exec(#SQL)
You can use COALESCE function.
Well,
I don't know if i understood your question, but i guess that you want to include the value of the code column in the results.
If i'm right it can be done in the select part instead of the where clause. i. e.
Select ..., case when code is not null then 8 else code end as code from emp where id = 7
The other interpretation is that you want to filter rows where code <> 8,that would be
Select * from emp where id = 7 and (code is null OR code = 8)