I am using teradata sql, and I have the following input
If col2 has (1,2,3) values then delete the Id from table, so my desired table is:
I tried all possible ways, but cannot get to eliminate the IDs? Any help or suggestion will help. thanks
DELETE FROM yourTable
WHERE Id IN ( SELECT Id FROM yourTable WHERE col2 IN (1,2,3) )
If you actually want to delete those IDs you better use #MudassirHasan's solution, but if you want to select the other IDs you can utilize Conditional Aggregation in a Group Max:
select *
from mytable
qualify
max(case when col2 (1,2,3) then 1 else 0 end) -- will return zero when those values don't exist
over (partition by id) = 0 -- for an ID
Related
I have a table with more than 15 columns. 2 of of them are of the type varchar, and most of them of type int and float.
I am new to SQL and am trying to figure out a way by which I can check if any of the columns have a NULL value in it.
Had there been just 4 or 5 columns I could have checked them individually with
SELECT COUNT(*) FROM table_name WHERE col1 IS NULL OR col2 IS NULL OR col3 IS NULL ...
But is there any efficient way to do this on a lot of columns in SQLite specifically?
I have referred to other questions regarding this here but I cannot use xml or store anything. Also I am using SQLite and can only run a query.
There is no way (that I know of) to check all columns if they contain null without explicitly listing all the column names.
Your query is the proper way to do it.
If you want to shorten (not significantly) the code you could use these alternatives:
SELECT COUNT(*) FROM table_name WHERE col1 + col2 + col3 IS NULL;
or:
SELECT COUNT(*) FROM table_name WHERE col1 || col2 || col3 IS NULL;
or:
SELECT COUNT(*) FROM table_name WHERE MAX(col1, col2, col3) IS NULL;
The above queries work, for any data type of the columns, because if there is even only 1 column equal to null then addition, concatenation and the scalar function MAX() (and MIN()) all return null.
See the demo.
My database structure contains columns: id, name, value, dealer. I want to retrieve row with lowest value for each dealer. I've been trying to mess up with MIN() and GROUP BY, still - no solution.
Solution1:
SELECT t1.* FROM your_table t1
JOIN (
SELECT MIN(value) AS min_value, dealer
FROM your_table
GROUP BY dealer
) AS t2 ON t1.dealer = t2.dealer AND t1.value = t2.min_value
Solution2 (recommended, much faster than solution1):
SELECT t1.* FROM your_table t1
LEFT JOIN your_table t2
ON t1.dealer = t2.dealer AND t1.value > t2.value
WHERE t2.value IS NULL
This problem is very famous, so there is a special page for this in Mysql's manual.
Check this: Rows Holding the Group-wise Maximum/Minimum of a Certain Column
select id,name,MIN(value) as pkvalue,dealer from TABLENAME
group by id,name,dealer;
here you group all rows by id,name,dealer and then you will get min value as pkvalue.
SELECT MIN(value),dealer FROM table_name GROUP BY dealer;
First you need to resolve the lowest value for each dealer, and then retrieve rows having that value for a particular dealer. I would do this that way:
SELECT a.*
FROM your_table AS a
JOIN (SELECT dealer,
Min(value) AS m
FROM your_table
GROUP BY dealer) AS b
ON ( a.dealer= b.dealer
AND a.value = b.m )
Try following:
SELECT dealer, MIN(value) as "Lowest value"
FROM value
GROUP BY dealer;
select id, name, value, dealer from yourtable where dealer
in(select min(dealer) from yourtable group by name, value)
These answers seem to miss the edge case of having multiple minimum values for a dealer and only wanting to return one row.
If you want to only want one value for each dealer you can use row_number partition - group - the table by dealer then order the data by value and id. we have to make the assumption that you will want the row with the smallest id.
SELECT ord_tbl.id,
ord_tbl.name,
ord_tbl.value,
ord_tbl.dealer
FROM (SELECT your_table.*,
ROW_NUMBER() over (PARTITION BY dealer ORDER BY value ASC, ID ASC)
FROM your_table
) AS ord_tbl
WHERE ord_tbl.ROW_NUMBER = 1;
Be careful though that value, id and dealer are indexed. If not this will do a full table scan and can get pretty slow...
I have a oracle query
select id from (
select ID, ROW_NUMBER() over (partition by LATEST_RECEIPT order by ID) rownumber
from Table
where LATEST_RECEIPT in
(
select LATEST_RECEIPT from Table
group by LATEST_RECEIPT
having COUNT(1) > 1
)
) t
where rownumber <> 1;
The data type of LATEST_RECEIPT was earlier varchar2(4000) and this query worked fine. Since the length of the column needs to be extended i modified it to CLOB, after which this fails. Could anyone help me fix this issue or provide a work around?
You can change your inner query to look for other rows with the same last_receipt value but a different ID (assuming ID is unique); if another row exists then that is equivalent to your count returning greater than one. But you can't simply test two CLOB values for equality, you need to use dbms_lob.compare:
select ID
from your_table t1
where exists (
select null from your_table t2
where dbms_lob.compare(t2.LATEST_RECEIPT, t1.LATEST_RECEIPT) = 0
and t2.ID != t1.ID
-- or if ID isn't unique: and t2.ROWID != t1.ROWID
);
Applying the row number filter is tricker, as you also can't use a CLOB in the analytic partition by clause. As André Schild suggested, you can use a hash; here passing the integer value 3, which is the equivalent of dbms_crypto.hash_sh1 (though in theory that could change in a future release!):
select id from (
select ID, ROW_NUMBER() over (partition by dbms_crypto.hash(LATEST_RECEIPT, 3)
order by ID) rownumber
from your_table t1
where exists (
select null from your_table t2
where dbms_lob.compare(t2.LATEST_RECEIPT, t1.LATEST_RECEIPT) = 0
and t2.ID != t1.ID
-- or if ID isn't unique: and t2.ROWID != t1.ROWID
)
)
where rownumber > 1;
It is of course possible to get a hash collision, and if that happened - you had two latest_receipt values which both appeared more than once and both hashed to the same value - then you could get too many rows back. That seems pretty unlikely, but it's something to consider.
So rather than ordering you can only look for rows which have the same lastest_receipt and a lower ID:
select ID
from your_table t1
where exists (
select null from your_table t2
where dbms_lob.compare(t2.LATEST_RECEIPT, t1.LATEST_RECEIPT) = 0
and t2.ID < t1.ID
);
Again that assumes ID is unique. If it isn't then you could still use rowid instead, but you would have less control over which rows were found - the lowest rowid isn't necessarily the lowest ID. Presumably you're using this to dine rows to delete. If you actually don't mind which row you keep and which you delete then you could still do:
and t2.ROWID < t1.ROWID
But since you are currently ordering that probably isn't acceptable, and hashing might be preferable, despite the small risk.
Example:
It does not work.
UPDATE column_name SET rownum FROM table_name
This work!
UPDATE table_name SET column_name = rownum;
This works but the update is performed incorrectly
SELECT * FROM table_name ORDER BY column_name;
UPDATE table_name SET column_name = rownum;
I wish the following update behavior:
Note:'rownum ' It is not a physical column of the table
/*
pc_comentario = tableName
cod_comentario = columnName (Reference column for sorting)
dtc_andamento = columnDay (Reference column to update the "columnName" according to the order of this column)
*/
rownum | columnName | columnDay
1 1 day 1
2 5 day 5
3 7 day 2
After change with update
rownum | columnName (Update this column) | columnDay (sort by this column)
1 1 day 1
2 2 day 2
3 3 day 5
ALMOST DONE! this column 'cod_comentario_1 "which was materialized in RAM is correct. I need this column" cod_comentario_1 "that does not exist in the table is acknowledged in the consultations with java.
SELECT cod_comentario, dtc_andamento, cod_processo ,
ROW_NUMBER()
OVER (PARTITION BY cod_processo
ORDER BY dtc_andamento) cod_comentario_1
FROM pc_comentario
upadate do not work this way:
UPDATE (
SELECT cod_processo
ROW_NUMBER()
OVER (PARTITION BY cod_processo
ORDER BY dtc_andamento)cod_comentario_1
FROM pc_comentario
) SET cod_comentario_1)
order by Seq
I must enter the values of this consultation in a new column that I created
SELECT
ROW_NUMBER()
OVER (PARTITION BY cod_processo
ORDER BY dtc_andamento DESC)
FROM pc_comentario
Try:
UPDATE table_name
SET column_name = rownum
Shouldn't it be like below rather; I believe UPDATE statement has no FROM clause
UPDATE table_name SET column_name = rownum;
Again, it will work only if rownum is an existing column in your table. If you are trying to use Oracle rownum instead then consider using row_number() function rather
update table_name set column_name =
select rn from ( select column_name, row_number() over (order by column_name) rn
from table_name ) xx;
As you state yourself, rownum is a virtual column. It assigns a sequential value to each row of a particular result set. Which means that the row number of a row could be completely different in the result set of a different query.
If you really want to show the row number as part of the result set, specify it as you would any column:
select rownum as columnName, columnDay
from table
order by ...;
I'm adding an 'index' column to a table in SQLite3 to allow the users to easily reorder the data, by renaming the old database and creating a new one in its place with the extra columns.
The problem I have is that I need to give each row a unique number in the 'index' column when I INSERT...SELECT the old values.
A search I did turned up a useful term in Oracle called ROWNUM, but SQLite3 doesn't have that. Is there something equivalent in SQLite?
You can use one of the special row names ROWID, OID or _ROWID_ to get the rowid of a column. See http://www.sqlite.org/lang_createtable.html#rowid for further details (and that the rows can be hidden by normal columns called ROWID and so on).
Many people here seems to mix up ROWNUM with ROWID. They are not the same concept and Oracle has both.
ROWID is a unique ID of a database ROW. It's almost invariant (changed during import/export but it is the same across different SQL queries).
ROWNUM is a calculated field corresponding to the row number in the query result. It's always 1 for the first row, 2 for the second, and so on. It is absolutely not linked to any table row and the same table row could have very different rownums depending of how it is queried.
Sqlite has a ROWID but no ROWNUM. The only equivalent I found is ROW_NUMBER() function (see http://www.sqlitetutorial.net/sqlite-window-functions/sqlite-row_number/).
You can achieve what you want with a query like this:
insert into new
select *, row_number() over ()
from old;
No SQLite doesn't have a direct equivalent to Oracle's ROWNUM.
If I understand your requirement correctly, you should be able to add a numbered column based on ordering of the old table this way:
create table old (col1, col2);
insert into old values
('d', 3),
('s', 3),
('d', 1),
('w', 45),
('b', 5465),
('w', 3),
('b', 23);
create table new (colPK INTEGER PRIMARY KEY AUTOINCREMENT, col1, col2);
insert into new select NULL, col1, col2 from old order by col1, col2;
The new table contains:
.headers on
.mode column
select * from new;
colPK col1 col2
---------- ---------- ----------
1 b 23
2 b 5465
3 d 1
4 d 3
5 s 3
6 w 3
7 w 45
The AUTOINCREMENT does what its name suggests: each additional row has the previous' value incremented by 1.
I believe you want to use the constrain LIMIT in SQLite.
SELECT * FROM TABLE can return thousands of records.
However, you can constrain this by adding the LIMIT keyword.
SELECT * FROM TABLE LIMIT 5;
Will return the first 5 records from the table returned in you query - if available
use this code For create Row_num 0....count_row
SELECT (SELECT COUNT(*)
FROM main AS t2
WHERE t2.col1 < t1.col1) + (SELECT COUNT(*)
FROM main AS t3
WHERE t3.col1 = t1.col1 AND t3.col1 < t1.col1) AS rowNum, * FROM Table_name t1 WHERE rowNum=0 ORDER BY t1.col1 ASC