I have a joa_clinics table which has a field grouper_id and that field is reflected as pcp_grouper_id in a joa_sales table. What I need is to get all the values in the joa_sales table with an additional dynamic column joa which would be 0 or 1 depending on whether the joa_sales table has pcp_gropuer_id value as null or not. Here is my query so far but it generates a syntax error on the second select:
SELECT * FROM joa_sales,
SELECT CASE WHEN g.GROUPER_ID IS NOT NULL THEN 1 ELSE 0 END AS JOA
FROM joa_clinics exp LEFT JOIN ( SELECT DISTINCT GROUPER_ID FROM joa_clinics ) g ON exp.PCP_GROUPER_ID = g.GROUPER_ID;
Maybe I don't even need to reference the joa_clinics table but don't know the syntax. The above sql is copied from a SQL Server syntax but mine is a Postgresql server.
Thank you!
Here is I think will work for me. No Join was needed:
SELECT * , CASE WHEN js.pcp_grouper_id IS NOT NULL THEN 1 ELSE 0 END AS JOA
FROM joa_sales js;
Related
I have this sql code where I try to display an alternative value as a result whenever the table is empty or the the single column of the top row when it is not
select top 1 case when count(*)!=0 then derrivedTable.primarykey
else 0 end endCase
from
(
select top 1 m.primarykey
from mytable m
where 0=1
)derrivedTable
The problem is that when I run this, I get the error message "column 'derrivedTable.primarykey' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause."
But when I put 'derrivedTable.primarykey' in the group by clause, I just get an empty table.
Does anyone hve a solution?
thanks in advance
You can use aggregation:
select coalesce(max(m.primarykey), 0)
from mytable m;
An aggregation query with no group by always returns exactly one row. If the table is empty (or all rows are filtered out), then the aggregation functions -- except for COUNT() -- return NULL -- which can be transformed to a value using COALESCE().
Such a construct makes me worry. If you are using this to set the primary key on an insert, then you should learn about identity columns or sequences. The database will do the work for you.
Can you try this below script-
SELECT
CASE
WHEN COUNT(*) = 1 THEN derrivedTable.primarykey
ELSE 0
END endCase
FROM
(
SELECT TOP 1 m.primarykey
FROM mytable m
WHERE 0 = 1
) derrivedTable
derrivedTable.primarykey;
I have two tables as the following
table1
main_id main_val main_sub main_pk
1 A NULL 3
3 A 1 3
table2
col_id col_val
1 A
select table1.main_pk from table1 ,table2 WHERE
table1.main_id = table2.col_id
and table1.main_val = table2.col_val
and table1.main_sub = null
Am expecting the above query to select the first row in table 1 as main_sub is null and the other two columns matches. But it does not. I am just learning SQL basics so am not sure where am going wrong. Please help
I didn't fully understand the question but I think this is what you want:
SELECT * from table1 INNER JOIN table2 on table1.main_val=table2.main_val WHERE table1.main_sub IS NULL
If not I think it directs you in the right path
SQL is a little weird about NULL values. Use the condition
....
table1.main_sub IS NULL
for testing for a null specifically. The idea is that NULL is supposed to be interpreted as nothing, so nothing -equals- nothing can't ever be true because you can't compare something that doesn't exist.
i have a problem in a db2 query
I tried run this query
SELECT t.* ,
CASE WHEN column in (SELECT data FROM otherTable WHERE conditions...)
then 5
else 0
end as 'My new data'
FROM table t
WHERE conditions....
But get error
[Error Code: -115, SQL State: 42601] [SQL0115] Comparison operator IN not valid.
When i change the sub-query to where statement like this
SELECT t.*
FROM table t
WHERE column in (SELECT data FROM otherTable WHERE conditions...)
Works fine
Why not work in the case statement? It is a limitation of db2?
And could make an equivalent behavior?
One way to do this is to left join to the table and check if it is not null.
In most cases this will be the fastest way because SQL servers are optimized to perform joins very quickly (but will depend on a number of factors including data model, indexes, data size, etc).
Like this:
SELECT t.* ,
CASE WHEN othertable.data is not null
then 5
else 0
end as 'My new data'
FROM table t
left join otherTable ON otherTable.column = data
WHERE conditions....
Try with using exists condition as below (put the column value in the where clause of subquery) :
SELECT t.* ,
CASE WHEN exists (SELECT data FROM otherTable WHERE conditions... and column=val)
then 5
else 0
end as 'My new data'
FROM table t
WHERE conditions....
I need to make a query but get the value in every field empty. Gordon Linoff give me the clue to this need here:
SQL Empty query results
which is:
select t.*
from (select 1 as val
) v left outer join
table t
on 1 = 0;
This query wors perfectly on PostgreSQL but gets an error when trying to execute it in Microsoft Access, it says that 1 = 0 expression is not admitted. How could it be fixed to work on microsoft access?
Regards,
If the table has a numeric primary key column whose values are non-negative then the following query will work in Access. The primary key field is [ID].
SELECT t2.*
FROM
myTable AS t2
RIGHT JOIN
(
SELECT TOP 1 (ID * -1) AS badID
FROM myTable AS t1
) AS rowStubs
ON t2.ID = rowStubs.badID
This was tested with Access 2010.
I am offering this answer here, even though you didn't think it worked in my edit to your original question. What is the problem?
select t.*
from (select max(col) as maxval from table as t
) as v left join
table as t
on v.val < t.col;
You can use the following query, but it would still need a little "manual coding".
EDITS:
Actually, you do not need the SWITCH function. Modified query below.
Removed the reference to Description column from one line. Still, you would need to use a Text column name (such as Description) in the last line of the query.
For example, the following query would work for the Months table:
select Months.*
from Months
RIGHT OUTER JOIN
(select "" as DummyColumn from Months) Blank_Data
ON Months.Description = Blank_Data.DummyColumn; --hardcoded Description column
Using Firebird:
I want to select a random entry in the table if the first SQL query returns 0 rows. Is there anyway to combine these two queries?
SELECT * FROM table WHERE cond=1;
SELECT FIRST 1 * FROM table ORDER BY rand();
Im using ExecuteNativeQuery on the java-side which takes basic SQL statements. Sadly, If-Else statements don't work. And if i could make a single query to the database instead of two, that would make my code appear faster.
try this: Not sure but think it will work...
Select FIRST 1 t1.*
FROM table t1
left Join Table t2
On t2.pk = t1.pk
And t2.cond=1
ORDER BY Case When t2.Cond = 1
Then 0 Else rand() End
if(exists(select 1 from table where cond=1))
SELECT * FROM table WHERE cond=1;
else
SELECT FIRST 1 * FROM table ORDER BY rand();
something like this, though I forgot whether the then keyword is needed in if statements in FirebirdSQL databases.