I am trying to write a SQL like below in DB2.
insert into tableA (col1, col2, col3)
select max(col1) + 1, '-2', col3
from tableA
where col2 = -1
Here the aim is copy all the record of tableA from -1 to -2 and here col1 is primary key and this should be increment by 1.
Now the problem is the select query will return more then one row like below
1001 -2 xyz
1001 -2 pqr
1001 -2 xdc
And it is not able to insert as the key is same.
Is there any way I can write the select sql so that it can return like below
1001 -2 xyz
1002 -2 pqr
1003 -2 xdc
and my insert will work, or is there any alternative way to the same with easiest way.
Note: The table do not have any trigger or some thing to auto increment the primary key.
Yes. Use row_number():
insert into tableA ( col1, col2, col3)
select max(col1) + row_number() over (order by col3), '-2', col3
from tableA
where col2 = -1
group by col3;
If you don't have a group by, then do:
insert into tableA ( col1, col2, col3)
select maxcol1 + row_number() over (order by col3), '-2', col3
from (select a.*, max(col1) over () as maxcol1
from tableA a
) a
where col2 = -1;
The right way to do this is to use a generated auto-incrementing value for col1. This code all has a problem if multiple threads are trying to do inserts at the same time.
Try this query !
insert into tableA (col1, col2, col3)
select (max(col1) + 1) as col1, '-2' as col2, col3
from tableA
where col2 = -1
Related
Col1
Col2
Col3
A
B
1
A
B
1
A
B
2
A
B
2
A
c
1
When col1 and Col2 values are same and Col3 values are different I dont want that values in result set.
I want result as below. I tried with row_number, group by , so manythings but did not worked. Please help me here
Col1
Col2
Col3
A
c
1
You can use exists:
delete from t
where exists (select 1
from t t2
where t2.col1 = t.col1 and t2.col2 = t.col1 and
t2.col3 <> t.col3
);
You can also use window functions:
with todelete as (
select t.*,
min(col3) over (partition by col1, col2) as min_col3,
max(col3) over (partition by col1, col2) as min_col4
from t
)
delete from todelete
where min_col3 <> max_col3;
Best way is to make these column a unique composite key. But here is a query to delete all records other than your desired result.
delete from Table_1
where
Col1=(SELECT Col1
FROM table_1
GROUP BY Col1, Col2
HAVING Count(*) > 1)
And
Col2 =(SELECT Col2
FROM table_1
GROUP BY Col1, Col2
HAVING Count(*) > 1)
this might not be the most optimized and efficient query but it works. if you don't want to delete duplicated records and just retrieve unique ones:
SELECT Col1,Col2
FROM table_1
GROUP BY Col1, Col2
HAVING Count(*) = 1
To get duplicating records:
SELECT Col2,Col1
FROM table_1
GROUP BY Col1, Col2
HAVING Count(*) > 1
I want to insert a row into the table if it does not exist.
I want to check if the col1 , col2 combination exists in the table.If not I have to insert the data.I have written a query like below , but it is not working.Can some one please help me.
INSERT INTO TABLE1 (COL1 , COL2 , COL3, COL4)
VALUES ( 1234 , 4567 , 'test_name_int' , 'test_disp_name' )
WHERE NOT EXISTS ( SELECT * FROM TABLE1 WHERE COL1 = 1234 and COL2 = '4567');
MERGE INTO is another good option. You could perform update too, if required.
This checks whether col1,col2 of the source and destination match. If they do not,then it does insert. you could also use WHEN MATCHED THEN UPDATE when required to do so.
MERGE INTO TABLE1 d
USING (SELECT 1235 COL1,
4568 COL2,
'test_name_int' COL3,
'test_disp_name' COL4
FROM DUAL) s
ON (d.COL1 = s.col1 AND d.COL2 = s.COL2)
WHEN NOT MATCHED
THEN
INSERT (COL1,
COl2,
COl3,
COl4)
VALUES (s.COl1,
s.COL2,
s.COL3,
s.COL4);
Maybe something like that:
Insert Into TABLE1
Select 1234 , 4567 , 'test_name_int' , 'test_disp_name'
From Dual
WHERE NOT EXISTS ( SELECT * FROM TABLE1 WHERE COL1 = 1234 and COL2 ='4567')
I need to get to first (min) date from a set of 4 (or more) columns.
I tried
select min (col1, col2, col3) from tbl
which is obviouslly wrong.
let's say I have these 4 columns
col1 | col2 | col3 | col4
1/1/17 | 2/2/17 | | 3/3/17
... in this case what I want to get is the value in col1 (1/1/17). and Yes, these columns can include NULLs.
I am running this in dashDB
the columns are Date data type,
there is no ID nor Primary key column in this table,
and I need to do this for ALL rows in my query,
the columns are NOT in order. meaning that col1 does NOT have to be before col2 or it has to be null AND col2 does NOT have to be before col3 or it has to be NULL .. and so on
If your DB support least function, it is the best approach
select
least
(
nvl(col1,TO_DATE('2901-01-01','YYYY-MM-DD')),
nvl(col2,TO_DATE('2901-01-01','YYYY-MM-DD')),
nvl(col3,TO_DATE('2901-01-01','YYYY-MM-DD')),
nvl(col4,TO_DATE('2901-01-01','YYYY-MM-DD'))
)
from tbl
Edit: If all col(s) are null, then you can hardcode the output as null. The below query should work. I couldn't test it but this should work.
select
case when
least
(
nvl(col1,TO_DATE('2901-01-01','YYYY-MM-DD')),
nvl(col2,TO_DATE('2901-01-01','YYYY-MM-DD')),
nvl(col3,TO_DATE('2901-01-01','YYYY-MM-DD')),
nvl(col4,TO_DATE('2901-01-01','YYYY-MM-DD'))
)
= TO_DATE('2901-01-01','YYYY-MM-DD')
then null
else
least
(
nvl(col1,TO_DATE('2901-01-01','YYYY-MM-DD')),
nvl(col2,TO_DATE('2901-01-01','YYYY-MM-DD')),
nvl(col3,TO_DATE('2901-01-01','YYYY-MM-DD')),
nvl(col4,TO_DATE('2901-01-01','YYYY-MM-DD'))
)
end
as min_date
from tbl
If a id column in your table. Then
Query
select t.id, min(t.col) as min_col_value from(
select id, col1 as col from your_table
union all
select id, col2 as col from your_table
union all
select id, col3 as col from your_table
union all
select id, col4 as col from your_table
)t
group by t.id;
If you want the first date, then use coalesce():
select coalesce(col1, col2, col3, col4)
from t;
This returns the first non-NULL value (which is one way that I interpret the question). This will be the minimum date, if the dates are in order.
Select Id, CaseWhen (Col1 <= Col2 OR Col2 is null) And (Col1 <= Col3 OR Col3 is null) Then Col1 When (Col2 <= Col1 OR Col1 is null) And (Col2 <= Col3 OR Col3 is null) Then Col2 Else Col3 End As Min From YourTable
This is for 3 Column, Same way you can write for 4 - or more column.
Is there a way to apply or not a group by into a query? for example, I have this:
Col1 Col2 Col3
A 10 X
A 10 NULL
B 12 NULL
B 12 NULL
I have to group by Col1 and Col2 only when I have a value in Col3, if Col3 is null, I don't need to group it. The result should be:
Col1 Col2
A 20
B 12
B 12
Maybe is not an elegant example, but this is the idea.
Thank you.
Here's a SQL Fiddle that does what you want:
http://sqlfiddle.com/#!3/b7f07/2
Here's the SQL itself:
SELECT col1, sum(col2) as col2 FROM dataTable WHERE
col1 in (SELECT col1 from dataTable WHERE col3 IS NOT NULL)
GROUP BY col1
UNION ALL
SELECT col1, col2 FROM dataTable WHERE
(col1 not in
(SELECT col1 from dataTable WHERE col3 IS NOT NULL and col1 is not null))
It sounds like you want all unique values of col1 when col3 is not null. Otherwise, you want all values of col1.
Assuming you have a SQL engine that supports window functions, you can do this as:
select col1, sum(col2)
from (select t.*,
count(col3) over (partition by col1) as NumCol3Values,
row_number() over (partition by col1 order by col1) as seqnum
from t
) t
group by col1,
(case when NumCol3Values > 1 then NULL else seqnum end)
The logic is pretty much as you state it. If there is any non-NULL value, then the second clause of the group by always evaluates to NULL -- everything goes in the same group. If things are all NULL, then the clause evaluates to a sequence number, which puts each values on a separate row.
This is a bit more difficult without window functions. If I assume that the minimum value of column 3 (when not NULL) is unique, then the following would work:
select t.col1,
(case when minCol3 is null then tsum.col2 else t.col2 end) as col2
from t left outer join
(select col1, sum(col2) as col2,
min(col3) as minCol3
from t
) tsum
on t.col1 = tsum.col1
where minCol3 is NULL or t.col3 = MinCol3
re: Is there a way to apply or not a group by into a query?
Not directly, but you can break it down by groupings and then UNION the results together.
Does this work?
Select col1, sum(col2)
from table
group by col1, col2
having max(col3) is not null
union all
select col1, col2
from table t left outer join
(Select col1, col2
from table
group by col1, col2
having max(col3) is not null) g
where g.col1 is null
In my table,some records have all column values are the same, except one. I need write a query to get those records. what's the best way to do it? the table is like this:
colA colB colC
a b c
a b d
a b e
What's the best way to get all records with all the columns? Thanks for everyone's help.
Assuming you know that column3 will always be different, to get the rows that have more than one value:
SELECT Col1, Col2
FROM Table t
GROUP BY Col1, Col2
HAVING COUNT(distinct col3) > 1
If you need all the values in the three columns, then you can join this back to the original table:
SELECT t.*
FROM table t join
(SELECT Col1, Col2
FROM Table t
GROUP BY Col1, Col2
HAVING COUNT(distinct col3) > 1
) cols
on t.col1 = cols.col1 and t.col2 = cols.col2
Just select those rows that have the different values:
SELECT col1, col2
FROM myTable
WHERE colWanted != knownValue
If this is not what you are looking for, please post examples of the data in the table and the wanted output.
How about something like
SELECT Col1, Col2
FROM Table
GROUP BY Col1, Col2
HAVING COUNT(*) = 1
This will give you Col1, Col2 that have unique data.
Assuming col3 has the difs
SELECT Col1, Col2
FROM Table
GROUP BY Col1, Col2
HAVING COUNT(*) > 1
OR TO SHOW ALL 3 COLS
SELECT Col1, Col2, Col3
FROM Table1
GROUP BY Col1, Col2, Col3
HAVING COUNT(Col3) > 1