can you tell me how to use CASE and IFNULL in postgre? i'm migrating from sql to postgreSQL, and i want to make a function with this syntax :
SELECT a.furniture_id, a.furniture_brand, a.furniture_cost,
CASE
WHEN furniture_id = f_id THEN a.furniture_content
ELSE ''
END CONTENT
FROM tb_furniture a
WHERE
(IFNULL(a.sale_id,0) = IFNULL(f_id,0) OR (a.furniture_id = f_Id AND IFNULL(a.furniture_content,'') > ''))
AND a.published = 1;
thanks before(y)
This seems to be what you are after, but carefully check the WHERE conditions:
SELECT a.furniture_id, a.furniture_brand, a.furniture_cost,
CASE WHEN a.furniture_id = f_id
THEN a.furniture_content
ELSE ''
END AS content
FROM tb_furniture a
WHERE (coalesce(a.sale_id,0) = coalesce(f_id,0) OR length(content) > 0)
AND a.published = 1;
Related
I don't know if this is possible, but this is the question. I try to change operator = by > if paramvalue = 0
AS $BODY$
declare
operator text;
begin
operator:='=';
if (paramvalue = 0) then
operator:='>';
end if;
select * from tablaname where id #operator 20
thanks!
I think overloading an operator is more complex than what you need for this behavior. You could try using a CASE statement instead.
SELECT *
FROM tablename
WHERE CASE WHEN paramvalue = 0
THEN id > 20
ELSE id = paramvalue
END
;
If you really want to overload an operator I suggest taking a look at the postgres documentation here.
REMARK NOT TESTED !!
In your scenario solution could be...:
.....
if (paramvalue = 0) then
select * from tablaname where id > 20
Else
select * from tablaname where id = 20
end if;
Please read this 9.16. Conditional Expressions
And this would be rather:
CASE WHEN paramvalue = 0 THEN select * from tablaname where id > 20
ELSE select * from tablaname where id = 20
END
I have a stored procedures and a few boolean variables (Bit).
I want to put a WHERE statement if a certain variables is False.
I know I could do something like this :
IF (#myBoolean = 1)
BEGIN
SELECT * FROM myTable
END
ELSE
SELECT * FROM myTable WHERE myTable.Foo = 'Bar'
Is there a way to make the WHERE statement optionnal ? Because I have so many boolean variable I don't want to have a different query for each possibilities.
This is what I have in mind (I know it does not work) :
SELECT * FROM myTable
CASE WHEN #myBoolean = 0
THEN WHERE myTable.Foo = 'Bar'
ELSE --Do nothing
SELECT * FROM myTable
where ( #myboolean = 1 and foo = 'bar' ) or #myboolean = 0
The below stored proc works fine except for the fact that when I uncomment the second part of the date check in the 'where' clause it blows up on a date conversion even if the passed in keyword is null or '111'.
I'm open to any suggestions on how to do this dynamic where clause differently.
I appreciate any help.
ALTER PROCEDURE [SurveyEngine].[GetPageOf_CommentsOverviewRowModel]
#sortColumn varchar(50),
#isASC bit,
#keyword varchar(50)
AS
BEGIN
declare #keywordType varchar(4)
set #keywordType = null
if ISDATE(#keyword) = 1
set #keywordType = 'date'
else if ISNUMERIC(#keyword) = 1
set #keywordType = 'int'
select c.CommentBatch BatchID, c.CreatedDate DateReturned, COUNT(c.CommentID) TotalComments
from SurveyEngine.Comment c
where (#keywordType is null)
or (#keywordType = 'date') --and c.CreatedDate = #keyword)
or (#keywordType = 'int' and (CONVERT(varchar(10), c.CommentBatch) like #keyword+'%'))
group by c.CommentBatch, c.CreatedDate
order by case when #sortColumn = 'BatchID' and #isASC = 0 then c.CommentBatch end desc,
case when #sortColumn = 'BatchID' and #isASC = 1 then c.CommentBatch end,
case when #sortColumn = 'DateReturned' and #isASC = 0 then c.CreatedDate end desc,
case when #sortColumn = 'DateReturned' and #isASC = 1 then c.CreatedDate end,
case when #sortColumn = 'TotalComments' and #isASC = 0 then COUNT(c.CommentID) end desc,
case when #sortColumn = 'TotalComments' and #isASC = 1 then COUNT(c.CommentID) end
END
EDIT Sorry, brain cloud. Things need to be initialized differently.
Change the setup to:
declare #keywordType varchar(4)
declare #TargetDate as DateTime = NULL
set #keywordType = null
if ISDATE(#keyword) = 1
begin
set #keywordType = 'date'
set #TargetDate = Cast( #keyword as DateTime )
end
else if ISNUMERIC(#keyword) = 1
set #keywordType = 'int'
Then change:
and c.CreatedDate = #keyword
to:
and c.CreatedDate = Coalesce( #TargetDate, c.CreatedDate )
That will result in a NOP if you are not searching by date.
Based on this guy's blog: http://blogs.msdn.com/b/bartd/archive/2011/03/03/don-t-depend-on-expression-short-circuiting-in-t-sql-not-even-with-case.aspx it looks like you can't guarantee the order of operations in the where clause, even though short circuiting is supported. The execution plan may choose to evaluate the second statement first.
He recommends using a case structure instead (like pst mentioned before) as it is "more" gauranteed. But I don't think I can rewrite your where clause as a case because you're using three different operators (is null, =, and LIKE).
Could anyone help me write up an If Else statement for iPhone's SQLite?
I need a:
IF (SELECT COUNT (*) FROM ..... WHERE ... = '..') > 0
BEGIN
SELECT * FROM .... WHERE ... = '...'
END
But I cannot get it to work. Is it even possible with SQLite.
Thanks for any help!
SELECT
*
FROM
....
WHERE
... = '...'
AND (SELECT COUNT (*) FROM ..... WHERE ... = '..') > 0
I have a huge query which uses case/when often. Now I have this SQL here, which does not work.
(select case when xyz.something = 1
then
'SOMETEXT'
else
(select case when xyz.somethingelse = 1)
then
'SOMEOTHERTEXT'
end)
(select case when xyz.somethingelseagain = 2)
then
'SOMEOTHERTEXTGOESHERE'
end)
end) [ColumnName],
Whats causing trouble is xyz.somethingelseagain = 2, it says it could not bind that expression. xyz is some alias for a table which is joined further down in the query. Whats wrong here? Removing one of the 2 case/whens corrects that, but I need both of them, probably even more cases.
SELECT
CASE
WHEN xyz.something = 1 THEN 'SOMETEXT'
WHEN xyz.somethingelse = 1 THEN 'SOMEOTHERTEXT'
WHEN xyz.somethingelseagain = 2 THEN 'SOMEOTHERTEXTGOESHERE'
ELSE 'SOMETHING UNKNOWN'
END AS ColumnName;
As soon as a WHEN statement is true the break is implicit.
You will have to concider which WHEN Expression is the most likely to happen. If you put that WHEN at the end of a long list of WHEN statements, your sql is likely to be slower. So put it up front as the first.
More information here: break in case statement in T-SQL
declare #n int = 7,
#m int = 3;
select
case
when #n = 1 then
'SOMETEXT'
else
case
when #m = 1 then
'SOMEOTHERTEXT'
when #m = 2 then
'SOMEOTHERTEXTGOESHERE'
end
end as col1
-- n=1 => returns SOMETEXT regardless of #m
-- n=2 and m=1 => returns SOMEOTHERTEXT
-- n=2 and m=2 => returns SOMEOTHERTEXTGOESHERE
-- n=2 and m>2 => returns null (no else defined for inner case)
If logical test is against a single column then you could use something like
USE AdventureWorks2012;
GO
SELECT ProductNumber, Category =
CASE ProductLine
WHEN 'R' THEN 'Road'
WHEN 'M' THEN 'Mountain'
WHEN 'T' THEN 'Touring'
WHEN 'S' THEN 'Other sale items'
ELSE 'Not for sale'
END,
Name
FROM Production.Product
ORDER BY ProductNumber;
GO
More information - https://learn.microsoft.com/en-us/sql/t-sql/language-elements/case-transact-sql?view=sql-server-2017