query 1
(select count(*) from CALENDAR)
it returns 15
query 2
(select value from PARAMETER where name = 'PLAN_HORIZON')
it returns 15 too only when my programs runs without error. if error occurs,
it returns 10 or other values.
this↓ is wrong sql, but i want a single query which returns True or False.
select if (query1 == query2)
How can I define 2 sql has same result in a query?
The following SQL statement returns 0 or 1. It runs with SQL Server
SELECT CASE WHEN (select count(*) from CALENDAR) = (select value from PARAMETER where name = 'PLAN_HORIZON') THEN 1 ELSE 0 END
Something like this:
select count(*) = 0
from (
select count(*)
from calendar
except
select value
from parameter
where name = 'PLAN_HORIZON'
) t
You didn't specify your DBMS, but the above is standard SQL.
Try this query !
SELECT
CASE
WHEN (select count(*) from CALENDAR) = (select value from PARAMETER
where name = 'PLAN_HORIZON')
THEN true
ELSE false
END ;
Related
I am having problem in part of my code anyway to do this
Only one expression can be specified in the select list when the subquery is not introduced with EXISTS. The update part is working but how to use insert into to calculate if a condition is not meant it will insert.
IF
/* CHECKLIST TO UPDATE*/
(NOT EXISTS
(SELECT *
FROM ENERGY.D_ENERGY_REFERENCE D_ENERGY_REFERENCE
,ENERGY.D_CHECK_LIST D_CHECK_LIST
WHERE D_ENERGY_REFERENCE.ID = D_CHECK_LIST.ID
AND D_ENERGY_REFERENCE.REFERENCE = 19051
)
)
BEGIN
INSERT INTO DB.D_ENERGY_REFERENCE(ID, REFERENCE_NO, REFERENCE,VALUE_INTEGER)
(SELECT ID,
(SELECT ISNULL(MAX(REFERENCE_NO), 0) + 1 FROM DB.D_ENERGY_REFERENCE),
19051, (SELECT D_CHECK_LIST.ID,
CASE
WHEN CAST(COUNT(CASE WHEN D_CHECK_LIST.EVALUATION NOT IN (0,1) THEN EVALUATION ELSE NULL END) AS FLOAT) = 0 THEN NULL
ELSE
(
CAST(COUNT(CASE WHEN D_CHECK_LIST.EVALUATION IN (2, 3, 50001, 50003, 50004, 50005, 50006, 50020, 50027, 50028) THEN EVALUATION ELSE NULL END) AS FLOAT)
/
CAST(COUNT(CASE WHEN D_CHECK_LIST.EVALUATION NOT IN (0,1) THEN EVALUATION ELSE NULL END) AS FLOAT)
) * 100
END FROM DB.D_CHECK_LIST
GROUP BY D_CHECK_LIST.ID)
FROM DB.D_ENERGY_REFERENCE D_ENERGY_REFERENCE
WHERE D_ENERGY_REFERENCE.ID = ID AND D_ENERGY_REFERENCE.REFERENCE = 19051
GROUP BY D_ENERGY_REFERENCE.ID
)
END
Can you please check this following part in the sub query of your script-
.......
19051,
(
SELECT
D_CHECK_LIST.ID, -- This is the column 1
CASE
WHEN -- Here you are generating column 2 in the sub query
......
)
Here you are selecting 2 column - one is "D_CHECK_LIST.ID" and other one is generation through CASE WHEN statement. I think you should SELECT any 1 column from those 2 column. If both are required, you can use separate Sub query for that.
The ERROR code "Only one expression can be specified in the select list when the subquery is not introduced with EXISTS" is self explanatory that you can not implement a Sub Query with more than 1 column selected unless the Sub Query is using inside EXISTS method.
I need to query based on the parameter, used parameter in the CASE clause.
Parameter will contain these values : contactSuccess,contactFail,notcontacted
We have column : empCommunication which is boolean. It will take 0,1, null
Based on the Parameter value, I need to run the query.
Eg: if Parameter is contactSuccess then Where clause should be
empCommunication = 1
if Parameter is contactFail then Where clause should be
empCommunication = 0
The above two scenario's are working with the below query, but if fails with
Parameter is notContacted, in this case Where clause should be
empCommunication IS NULL.
Kindly help me on this.
SELECT
empCategory as name,
count(*) as value
from EmployeeRecords R
WHERE empCommunication =
CASE ?
WHEN 'contactSuccess' THEN 1
WHEN 'contactFail' THEN 0
WHEN 'notcontacted' THEN IS NULL
END
group by empCategory
Use coalesce() to cover the case where the parameter is 'notcontacted' with a different value like -1:
SELECT
empCategory as name,
count(*) as value
from EmployeeRecords R
WHERE coalesce(empCommunication, -1) =
CASE ?
WHEN 'contactSuccess' THEN 1
WHEN 'contactFail' THEN 0
WHEN 'notcontacted' THEN -1
END
group by empCategory
Assume that your param is p_param, you could change your query to
SELECT
empCategory AS name,
COUNT(*) AS value
FROM EmployeeRecords
WHERE
(empCommunication IS NULL AND p_param = 'notcontacted')
OR (empCommunication = 1 AND p_param = 'contactSuccess')
OR (empCommunication = 0 AND p_param = 'contactFail')
GROUP BY empCategory;
Try this one!
SELECT
empCategory as name,
count(*) as value
from EmployeeRecords R WHERE empCommunication =
(CASE a_column_in_table
WHEN 'contactSuccess' THEN 1
WHEN 'contactFail' THEN 0
WHEN 'notcontacted' THEN NULL
else null
END)
group by empCategory;`
What is better approach to check existence of an object in database?
select count(id) as count from my_table where name="searchedName";
OR
select id from my_table where name="searchedName";
And then check if count > 0 or the object is not null (ORM logic)
EDIT:
select id to be valid for Oracle.
The idea should be to that we only need to find one record in order to say that such record exists. This can be done with an EXISTS clause in standard SQL.
select exists (select * from mytable where name = 'searchedName');
returns true if the table contains a record with 'searchedName' and false otherwise.
If you want 0 for false and 1 for true instead (e.g. if the DBMS does not support booleans):
select case when exists (select * from mytable where name = 'searchedName')
then 1 else 0 end as does_exist;
You say you want this for Oracle. In Oracle you can use above query, but you'd have to select from the table dual:
select case when exists (select * from mytable where name = 'searchedName')
then 1 else 0 end as does_exist
from dual;
But for Oracle we'd usually use rownum instead:
select count(*) as does_exist
from mytable
where name = 'searchedName'
and rownum = 1; -- to find one record suffices and we'd stop then
This also returns 1 if the table contains a record with 'searchedName' and 0 otherwise. This is a very typical way in Oracle to limit lookups and the query is very readable (in my opinion).
I'd just call:
select id from my_table where name='searchedName';
Making sure there is an index for the name column.
And then check whether or not the result is empty.
Try with IF EXISTS (
if exists (select 1 from my_table where name = "searchedName")
begin
....
end
How do I achieve this using SQL case statement?
select count(*) x from t_table where file_id = 310012;
if x<>0 : select distinct status from t_table where file_id = 310012
else : return x
See the code below:
SELECT CASE COUNT(*)
WHEN COUNT(*) > 0 THEN
(SELECT status FROM t_table WHERE file_id = 310012)
ELSE null END AS x
FROM t_table WHERE file_id = 310012;
You can do what you want with a union all:
select distinct status
from t_table
where file_id = 310012
union all
select 0
from dual
where not exists (select 1 from t_table where tile_id = 320023);
However, returning a single row with 0 seems like a bad idea, because it could be confused with a value status.
Note: You should use '0' if status is a string.
You don't need to count records. Just do only one query:
select distinct status from t_table where file_id = 310012
When the query return some rows, then x must be <> 0
If the query returns an empty resultset, then x must be equal to 0, and you get the second part of if x <> 0 then ..... else return x
As a bonus you get a higher processing speed, because you run only one query against the table, not two.
I have a sub query that returns one column, showing as GroupType, I then want to do a CASE function on this result within the main query, however I get an invalid column name when using the CASE statement.
Can i do this in SQL to do I have to refer to it by a different name
SELECT CASE
WHEN
(
SELECT column
FROM othertable
) = 1
THEN '1'
ELSE '2'
END
FROM mytable
To reuse the subquery result:
SELECT subvalue, CASE subvalue WHEN 1 THEN 1 ELSE 2 END
FROM (
SELECT (
SELECT column
FROM othertable
) AS subvalue
FROM mytable
) q