I need to delete the repeated row-
I have this table-
source
The result that I need-
result
*keep only one combination of 2 column (the order is not important)
Thanks! (:
Here is one method that should be efficient:
select col1, col2
from t
where col1 <= col2
union all
select col1, col2
from t
where col1 > col2 and
not exists (select 1 from t t2 where t2.col1 = t.col2 and t2.col2 = t.col1);
Note: This is a SQL select statement, so it does not delete rows in the table. You seem to want the results from a query, not to modify the underlying table.
My interpretation of the spec "keep only one combination of 2 column, [column] order not important":
SELECT col1, col2
FROM t
WHERE col1 <= col2
UNION
SELECT col2, col1
FROM t
WHERE col1 > col2;
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 have 2 SQL's and the result come fine. They are no relation between those 2 queries but I want to see all the rows in single column.
e.g.
Select col1,col2,sum(col3) as col3 from table a
select col4,col5 from table b
I would like the result to be
col1 col2 col3 col4 col5
If there is no equivalent row for either table a or table b replace with zeroes.
Could some one help me with this. thanks.
Since, you didn't provided any information like table structure or data inside each tables. You can cross join both tables.
select t.col1,t.col2,t.col3,t1.col1,t1.col2 from tab1 t,tab2 t1;
SQLFiddle
In both select statements add column based on rownum or row_number() and then full join results using this column:
select nvl(col1, 0) col1, nvl(col2, 0) col2, nvl(col3, 0) col3,
nvl(col4, 0) col4, nvl(col5, 0) col5
from
(select rownum rn, col1, col2, col3 from (
select col1, col2, sum(col3) col3 from tableA group by col1, col2)) a
full join (select rownum rn, col4, col5 from tableB) b using (rn)
SQLFiddle demo
I guess a UNION could be a pragmatic solution since the 2 queries are not related. They are just 2 data sets that should be retrieved in one statement:
Select col1,col2,sum(col3) as col3 from table a
UNION
select col4,col5, to_number(null) col6 from table b
Be aware of col6 in the example. SQL insists on retrieving an equal set of columns in a UNION statement. It is a good practice to retrieve columns with exactly the same datatype. Since the sum(col3) will yield a number datatype column, col6 should too.
The outcome of col4 and col5 will be shown in col1 and col2.
I have a dataset with about a million rows in and Oracle 11 db.
I'd like to find rows where col1 and col2 match but have different values in col3.
I'm not sure how to do this well though i can certainly write a query that never seems to finish:
select col1,col2,col3
from table tab1
where exists
(select 1
from table tab2
where tab1.col1 = tab2.col1
and tab1.col2 = tab2.col2
and tab1.col3 != tab2.col3);
I ran this and after an hour gave up waiting - I need to analyze the problems and present it to some people for figuring out how to move forward.
Thanks in any case,
Jeff
A query like this will indicate which rows having the same col1, col2 have differing values in col3:
SELECT col1, col2
FROM x
GROUP BY col1, col2
HAVING MIN(col3) <> MAX(col3)
To see how many of this col1, col2 pairs are affected:
SELECT COUNT(*)
FROM (SELECT col1, col2
FROM x
GROUP BY col1, col2
HAVING MIN(col3) <> MAX(col3)
)
You may also wish to know how many duplicates there are (ie having col1, col2, col3 the same:
SELECT col1, col2, col3
FROM x
GROUP BY col1, col2, col3
HAVING COUNT(*) > 1
Did you mean something like this?
select col1,col2,col3
from table tab1
where col1 = col2
and col1 <> col3
I have a SQLite table like this:
Col1 Col2 Col3
1 ABC Bill
2 CDE Fred
3 FGH Jack
4 CDE June
I would like to find the row containing a Col2 value of CDE which has the max Col1 value i.e. in this case June. Or, put another way, the most recently added row with a col2 value of CDE, as Col1 is an auto increment column. What is an SQL query string to achieve this? I need this to be efficient as the query will run many iterations in a loop.
Thanks.
SELECT * FROM table WHERE col2='CDE' ORDER BY col1 DESC LIMIT 1
in case if col1 wasn't an increment it would go somewhat like
SELECT *,MAX(col1) AS max_col1 FROM table WHERE col2='CDE' GROUP BY col2 LIMIT 1
Try this:
SELECT t1.*
FROM table1 t1
INNER JOIN
(
SELECT MAX(col1) MAXID, col2
FROM table1
GROUP BY col2
) t2 ON t1.col1 = t2.maxID AND t1.col2 = t2.col2
WHERE t1.col2 = 'CDE';
SQL Fiddle Demo1
1: This demo is mysql, but it should work fine with the same syntax in sqlite.
Use a subquery such as:
SELECT Col1, Col2, Col3
FROM table
WHERE Col1 = (SELECT MAX(Col1) FROM table WHERE Col2='CDE')
Add indexes as appropriate, e.g. clustered index on Col1 and another nonclustered index on Col2 to speed up the subquery.
In SQLite 3.7.11 and later, the simplest query would be:
SELECT *, max(Col1) FROM MyTable WHERE Col2 = 'CDE'
As shown by EXPLAIN QUERY PLAN, both this and passingby's query are most efficient, if there is an index on Col2.
If you'd want to see the correspondig values for all Col2 values, use a query like this instead:
SELECT *, max(Col1) FROM MyTable GROUP BY Col2
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