Let's say I have table like this:
Column1 Column2
C 2
B 1
A 3
I need to exchange values in the second column to get this:
Column1 Column2
C 3
B 2
A 1
The goal is only for numeric column to have values sorted to follow alphabetical order on another column. The actual table has multiple columns and column 1 is people's name, while column 2 two is rank for rendering column 1 values in UI.
What is the most optimal way to do this?
I am doing this from C# code, on SQL server and have to use System.Data.SqlClient.SqlCommand because of transaction. But maybe it's not important if this can all be done from SQL.
Thank you!
So you need to update Column2 with the row-number according toColumn1?
You can use ROW_NUMBER and a CTE:
WITH CTE AS
(
SELECT Column1, Column2, RN = ROW_NUMBER() OVER (ORDER BY Column1)
FROM MyTable
)
UPDATE CTE SET Column2 = RN;
This updates the table MyTable and works because the CTE selects a single table. If it contains more than one table you have to JOIN the UPDATE with the CTE.
Demo
Related
This is my table with 4 columns:
a b e d
a f c d
I want to get all 1st and 4th columns, so that the first two rows will be merged into one row in the example, since they are the same:
a d
a d
When I use the command:
select column1, column4 from my_table;
Would this automatically remove duplicates? If not, how to get distinct rows with only the 1 and 4 columns?
little confusing question.
Do you want to delete duplicate data or you want to just select non-duplicate data?
If you want to delete duplicate data then it will be like this -
insert overwrite my_table
select * from my_table
join (
Select col1||col2||col3||col4 key, row_number() over (partition by col1,col4 order by col1 ) as rn
from my_table) rs on rs.key = col1||col2||col3||col4 and rs.rn=1
If you want to select the unique col1 and col4 and dont want to change underlying data, you can simply fire
select distinct column1, column4 from my_table;
I have a table form which I need to extract some information. This table has an oracle spatial (MDSYS.SDO_GEOMETRY) column, from which I also need some data.
I started out with a simple query like this:
select id, field1, field2
FROM my_table;
After that, I was able to loop over the result to extract the data that was in the spatial column:
SELECT *
FROM TABLE (SELECT a.POSITIONMAP.sdo_ordinates
FROM my_table
WHERE ID = 18742084);
The POSITIONMAP.sdo_ordinates seems to usually hold 4 values, like these:
100050,887
407294,948
0,577464740471056
-0,816415625470689
I need the last 2 values. I can achieve that by changing the query into this:
SELECT * FROM
(SELECT rownum AS num,
column_value AS orientatie
FROM TABLE (SELECT a.POSITIONMAP.sdo_ordinates
FROM my_table
WHERE ID = 18742084))
WHERE num IN (3,4)
Looping over every row from my first query to extract the data from the POSITIONMAP column is of course not very performance friendly, so my query becomes slow very quickly.
I would like to retrieve all information in one query, but there are a few things that prevent me from doing so.
Not every row in the table has data in POSITIONMAP
Some rows do have data in POSITIONMAP, but they only contain 2 values (so not the 3rd and 4th value that I am looking for.
I need the data in one row for every row in the table (using the previous query would result in duplicate rows
The closest I got is:
select
id,
field1,
field2
t.*
FROM my_table v,
table (v.POSITIONMAP.sdo_ordinates) t
This gives my 4 rows for every row in my_table.
As soon as I try to put the rownum condition into this query, I get an error: "invalid user.table.column, table.column, or column specification"
Is there any way to combine what I want to do into 1 query?
You can use sdo_util.getvertices as follows:
select t.x,t.y
from my_table mt
,table(sdo_util.getvertices(mt.positionmap)) t
where t.id = 2
I'm assuming that your geometries are lines (gtype=2002) and points (gtype= 2001). If you want X,Y values for lines and empty values for point you can filter on the sdo_gtype property of the geometry object.
select t.x,t.y
from my_table mt
,table(sdo_util.getvertices(mt.positionmap)) t
where t.id = 2
and mt.positionmap.sdo_gtype=2002
union all
select null as X,
null as Y
from my_table mt
where mt.positionmap.sdo_gtype=2001
One method is to use the ROW_NUMBER() analytic function:
SELECT *
FROM (
select id,
field1,
field2,
t.*,
ROW_NUMBER() OVER ( PARTITION BY v.id ORDER BY ROWNUM ) AS rn
FROM my_table v,
TABLE( v.POSITIONMAP.sdo_ordinates ) t
)
WHERE rn IN ( 3, 4 )
i have searched but i did not find any good answer actually i got the distinct value but the problem is i am applying query on two columns it should return distinct values but it is returning these values
Au |FAA303
Au |FAA505
From my table i want to appear Au only one time as it is now associated with the FAA303 and FAA505
What i want is like this
Au |FAA303
|FAA505
This is my query in postgresql. I am kinda new to the database queries.
select distinct column1, column2
from table_name
The distinct keyword applies to the combination of all selected fields, not to the first one only.
Suppressing repeated values is something you would typically do in an application that connects to your database and performs the query.
Just to show you that it is possible in SQL, I provide you this query, but please consider doing this in the application instead:
select case row_number() over (partition by column1 order by column2)
when 1 then column1
end as column1,
column2
from (
select distinct column1,
column2
from table_name
order by column1, column2
)
I am trying to update a table with records from another table. Whenever I use the insert into statement, I find that the records are simply appended. Instead, I want the records to be inserted from the top of the table. What is the easiest way to do this? I am thin king I could use a update statement, but that means I will have to join the tables. One of the tables(the one I am pulling records from) has only one column. As such, I would have to include another column to do the join.I am trying not to make it so complicated. If there is a simplier way, please let me know.
Sample:
Table One
Col1
1
2
3
4
Table 2
Col1 Col2
a
b
c
d
I want to move column 1 from table 1 to column 2 in table 2 such that table 2 will be:
Table 2
Col1 Col2
a 1
b 2
c 3
d 4
You can do the update using row_number(), but the rows will be assigned in an indeterminate order:
with toupdate as (
select t2.*, row_number() over (select NULL)) as seqnum
from table2 t2
),
t1 as (
select t1.*, row_numbrer() over (select NULL)) as seqnum
from table1 t1
)
update toupdate
set col2 = t1.col1
from toupdate join
t1
on toupdate.seqnum = t1.seqnum;
Note: if you have an ordering in mind, then use the appropriate order by in the partition clauses.
Unless you explicity define an ORDER BY clause in your SELECT statements, your result set will be completely arbitrary. This is in line with how any RDBMS should operate. You should consider including a timestamp at the time of insertion to identify the latest rows.
I have a table with 10 columns.
I want to return all rows for which Col006 is distinct, but return all columns...
How can I do this?
if column 6 appears like this:
| Column 6 |
| item1 |
| item1 |
| item2 |
| item1 |
I want to return two rows, one of the records with item1 and the other with item2, along with all other columns.
In SQL Server 2005 and above:
;WITH q AS
(
SELECT *, ROW_NUMBER() OVER (PARTITION BY col6 ORDER BY id) rn
FROM mytable
)
SELECT *
FROM q
WHERE rn = 1
In SQL Server 2000, provided that you have a primary key column:
SELECT mt.*
FROM (
SELECT DISTINCT col6
FROM mytable
) mto
JOIN mytable mt
ON mt.id =
(
SELECT TOP 1 id
FROM mytable mti
WHERE mti.col6 = mto.col6
-- ORDER BY
-- id
-- Uncomment the lines above if the order matters
)
Update:
Check your database version and compatibility level:
SELECT ##VERSION
SELECT COMPATIBILITY_LEVEL
FROM sys.databases
WHERE name = DB_NAME()
The key word "DISTINCT" in SQL has the meaning of "unique value". When applied to a column in a query it will return as many rows from the result set as there are unique, different values for that column. As a consequence it creates a grouped result set, and values of other columns are random unless defined by other functions (such as max, min, average, etc.)
If you meant to say you want to return all rows for which Col006 has a specific value, then use the "where Col006 = value" clause.
If you meant to say you want to return all rows for which Col006 is different from all other values of Col006, then you still need to specify what that value is => see above.
If you want to say that the value of Col006 can only be evaluated once all rows have been retrieved, then use the "having Col006 = value" clause. This has the same effect as the "where" clause, but "where" gets applied when rows are retrieved from the raw tables, whereas "having" is applied once all other calculations have been made (i.e. aggregation functions have been run etc.) and just before the result set is returned to the user.
UPDATE:
After having seen your edit, I have to point out that if you use any of the other suggestions, you will end up with random values in all other 9 columns for the row that contains the value "item1" in Col006, due to the constraint further up in my post.
You can group on Col006 to get the distinct values, but then you have to decide what to do with the multiple records in each group.
You can use aggregates to pick a value from the records. Example:
select Col006, min(Col001), max(Col002)
from TheTable
group by Col006
order by Col006
If you want the values to come from a specific record in each group, you have to identify it somehow. Example of using Col002 to identify the record in each group:
select Col006, Col001, Col002
from TheTable t
inner join (
select Col006, min(Col002)
from TheTable
group by Col006
) x on t.Col006 = x.Col006 and t.Col002 = x.Col002
order by Col006
SELECT *
FROM (SELECT DISTINCT YourDistinctField FROM YourTable) AS A
CROSS APPLY
( SELECT TOP 1 * FROM YourTable B
WHERE B.YourDistinctField = A.YourDistinctField ) AS NewTableName
I tried the answers posted above with no luck... but this does the trick!
select * from yourTable where column6 in (select distinct column6 from yourTable);
SELECT *
FROM harvest
GROUP BY estimated_total;
You can use GROUP BY and MIN() to get more specific result.
Lets say that you have id as the primary_key.
And we want to get all the DISTINCT values for a column lets say estimated_total, And you also need one sample of complete row with each distinct value in SQL. Following query should do the trick.
SELECT *, min(id)
FROM harvest
GROUP BY estimated_total;
create table #temp
(C1 TINYINT,
C2 TINYINT,
C3 TINYINT,
C4 TINYINT,
C5 TINYINT,
C6 TINYINT)
INSERT INTO #temp
SELECT 1,1,1,1,1,6
UNION ALL SELECT 1,1,1,1,1,6
UNION ALL SELECT 3,1,1,1,1,3
UNION ALL SELECT 4,2,1,1,1,6
SELECT * FROM #temp
SELECT *
FROM(
SELECT ROW_NUMBER() OVER (PARTITION BY C6 Order by C1) ID,* FROM #temp
)T
WHERE ID = 1