I'm using SQLite and have two tables:
Line {
Element_ID,
length
}
Element{
Element_ID,
Name
}
I want to update the parameter "length" to a certain value in Line by specifying the "Name" in Element where Element_ID is the same for Line and Element.
SQLite does not support the JOIN statement in combination with the UPDATE statement, so I've been trying various combinations of UPDATE with EXISTS without any success. Example; update length to 2 for the line with element Name 'c18':
UPDATE Line
SET length = 2
WHERE EXISTS (SELECT length FROM Line WHERE Line.Element_ID = Element.Element_ID AND Element.Name = 'c18')
Result: Error: No such column: Element.Element_ID
UPDATE Line
SET length = 2
WHERE EXISTS (SELECT length FROM Line INNER JOIN Element ON Line.Element_ID = Element.Element_ID WHERE Element.Name = 'c18')
Result: The code updates length for ALL lines (it looks like it disregards the last part in the EXISTS-statement WHERE Element.Name = 'c18'. I don't understand why this is happening, because if I only run the SELECT-statement inside the WHERE EXISTS(..) the program selects the correct line (c18).
Can anyone help me with this?
The first query doesn't work because you are referencing Element in the WHERE clause without defining it anywhere (as a table or an alias).
The second one because the subquery does not depend on the main query (it is not a correlated subquery) and therefore it has the same value for every row.
A simpler way to do this could be :
UPDATE Line SET length = 2
WHERE Element_ID in ( SELECT Element_ID FROM Element WHERE Name = 'c18' )
or to make it a bit more explicit :
UPDATE Line SET length = 2
WHERE Element_ID in ( SELECT e.Element_ID FROM Element e WHERE e.Name = 'c18' )
Related
I need to merge some randomly uppercased data that has been collected in an SQLite table key_val, such that key is always lowercase and no vals are lost. There is a unique compound index on key,val.
The initial data looks like this:
key|val
abc|1
abc|5
aBc|1
aBc|5
aBc|3
aBc|2
AbC|1
abC|3
The result after the merge would be
key|val
abc|1
abc|2
abc|3
abc|5
In my programmer brain, I would
for each `key` with upper case letters;
if a lower cased `key` is found with the same value
then delete `key`
else update `key` to lower case
Re implementing the loop has a sub query for each row found with upper case letters, to check if the val already exists as a lower case key
If it does, I can delete the cased key.
From there I can UPDATE key = lower(key) as the "duplicates" have been removed.
The first cut of the programming method of finding the dupes is:
SELECT * FROM key_val as parent
WHERE parent.key != lower(parent.key)
AND 0 < (
SELECT count(s.val) FROM key_val as s
WHERE s.key = lower(parent.key) AND s.val = parent.val
)
ORDER BY parent.key DESC;
I'm assuming there's a better way to do this in SQLite? The ON CONFLICT functionality seems to me like it should be able to handle the dupe deletion on UPDATE but I'm not seeing it.
First delete all the duplicates:
DELETE FROM key_val AS k1
WHERE EXISTS (
SELECT 1
FROM key_val AS k2
WHERE LOWER(k2.key) = LOWER(k1.key) AND k2.val = k1.val AND k2.rowid < k1.rowid
);
by keeping only 1 combination of key and val with the min rowid.
It is not important if you kept the key with all lower chars or not, because the 2nd step is to update the table:
UPDATE key_val
SET key = LOWER(key);
See the demo.
Honestly it might just be easier to create a new table and then insert into it. As it seems you really just want a distinct select here, use:
INSERT INTO kev_val_new ("key", val)
SELECT DISTINCT LOWER("key"), val
FROM key_val;
Once you have populated the new table, you may drop the old one, and then rename the new one to the previous name:
DROP TABLE key_val;
ALTER TABLE key_val_new RENAME TO key_val;
I agree with #Tim that it would be easire to re-create table using simple select distict lower().. statement, but that's not always easy if table has dependant objects (indexes, triggers, views). In this case this can be done as sequence of two steps:
insert lowered keys which are not still there:
insert into t
select distinct lower(tr.key) as key, tr.val
from t as tr
left join t as ts on ts.key = lower(tr.key) and ts.val = tr.val
where ts.key is null;
now when we have all lowered keys - remove other keys:
delete from t where key <> lower(key);
See fiddle: http://sqlfiddle.com/#!5/84db50/11
However this method assumes that key is always populated (otherwise it would be a strange key)
If vals can be null then "ts.val = tr.val" should be replaced with more complex stuff like ifnull(ts.val, -1) = ifnull(tr.val, -1) where -1 is some unused value (can be different). If we can't assume any unused value like -1 then it should be more complex check for null / not null cases.
I am using this code;
sql = "UPDATE SCORE SET A = 1 WHERE ID = 12 AND COUNT = 25";
db2.Execute(sql);
Is there a way that I can execute this kind of statement and find out if the update actually found and updated a row?
The execute method returns the number of rows modified. So
var rowsModified = db2.Execute(sql);
if(rowsModified > 0)
{
// the statement found at least one row to update
}
Modified means in this case that a row to update was found. So, it is counted as a modification even when the statement results in assigning the same values already present in the row.
I want use this procedure to display the username and moblephone number,the result sets is this when I use select :
declare enter image description here
when the procedure runs,I get this :
enter image description here
error ORA-01722: invalid number
ORA-06512: at "ABPROD.SHAREPOOL", line 24.
when I use unique or distinct in the cursor,nothing display.
the code source :
create or replace procedure sharepool (assignment in varchar2,myorgname in varchar2) is
rightid T_CLM_AP30_RIGHT.RIGHT_ID%type;
orgid t_clm_ap30_org.org_id%type;
begin
select t.right_id into rightid from T_CLM_AP30_RIGHT t where t.rightdesc=trim(assignment);
dbms_output.put_line(rightid||trim(myorgname)||assignment);
select t.org_id into orgid from t_clm_ap30_org t where t.orgname=trim(myorgname);
dbms_output.put_line(orgid);
declare
cursor namelist is select distinct a.username,a.mobile from t_clm_ap30_user a, T_CLM_AP30_RIGHT_AUTH t where a.user_id=t.user_id and t.right_id=rightid and t.poolorgrange=orgid ;
begin
for c in namelist
loop
dbms_output.put_line(c.username||' '||c.mobile);
end loop;
end;
end sharepool;
INVALID_NUMBER errors indicate a failed casting of a string to a number. That means one of your join conditions is comparing a string column with a number column, and you have values in the string column which cannot be cast to a number.
ORA-06512: at "ABPROD.SHAREPOOL", line 24
Line 24 doesn't align with the code you've posted, presumably lost in translation from your actual source. Also you haven't posted table descriptions so we cannot tell which columns to look at.
So here is a guess.
One (or more) of these joins has an implicit numeric conversion:
where a.user_id = t.user_id
and t.right_id = rightid
and t.poolorgrange = orgid
That is, either t_clm_ap30_user.user_id is numeric and T_CLM_AP30_RIGHT_AUTH.user_id is not, or vice versa. Or T_CLM_AP30_RIGHT_AUTH.right_id is numeric and T_CLM_AP30_RIGHT.right_id is not, or vice versa. Or T_CLM_AP30_RIGHT_AUTH.poolorgrange is numeric and t_clm_ap30_org.org_id is not, or vice versa.
Only you can figure this out, because only you can see your schema. Once you have identified the join where you have a string column being compared to a numeric column you need to query that column to find the data which cannot be converted to a number.
Let's say that T_CLM_AP30_RIGHT_AUTH.poolorgrange is the rogue string. You can see which are the troublesome rows with this query:
select * from T_CLM_AP30_RIGHT_AUTH
where translate (poolorgrange, 'x1234567890', 'x') is not null;
The translate() function strips out digits. So anything which is left can't be converted to a number.
"T_CLM_AP30_RIGHT_AUTH.poolorgrange is varchar2,and t_clm_ap30_org.org_id is numeric ."
You can avoid the error by explicitly casting the t_clm_ap30_org.org_id to a string:
select distinct a.username, a.mobile
from t_clm_ap30_user a,
T_CLM_AP30_RIGHT_AUTH t
where a.user_id = t.user_id
and t.right_id = rightid
and t.poolorgrange = to_char(orgid) ;
Obviously you're not going to get matches on those alphanumeric values but the query will run.
I want to use variable in my query for sqlite but I don't know how do it?
my query is it :
/*I want to declare my variable in here and use this variable query*/
/*declare vaiable*/SELECT direct_station.iddirect_station,station.name,line.color FROM direct_station JOIN
direction ON direction.iddirection = direct_station.iddirection JOIN
station ON station.idstation = direction.laststation JOIN line ON line.idline = direction.line WHERE direct_station.idstation = /*put variable*/
Explain :
my friends I want execute one query but this query have two part :
first part I want to get several value like this {178,180,200,300}. I got this from this query :
SELECT direct_station.iddirect_station FROM direct_station WHERE direct_station.idstation = 98
and second part I want to use any these values to this query by one variable :
SELECT * FROM stations_view WHERE iddirection = %d
now I want to get any value from second query that joined to first query.
I think that the solution could be to create a Table for your variable where you are going to store the variable's value and from where you can retrieve the value when needed.
INSERT INTO VariableTable (Variable) VALUES ('x');
SELECT * FROM TableName WHERE ColumnName = (SELECT Variable FROM VariableTable);
I am doing an school assigment where I need to get the last value of "code" so I can then insert next row with this code incremented. I tried to pull it out this way.
DECLARE
v_last_code f_shifts.code%TYPE;
BEGIN
SELECT LAST_VALUE(code) OVER (ORDER BY code)
INTO v_last_code
FROM f_shifts;
DBMS_OUTPUT.PUT_LINE('Last value is: ' || v_last_code);
END;
However I get ORA-01422: exact fetch returns more than one requested number of rows
and I have no idea why and how can a last_value be more than one row
Thanks !
You can use a nested table like this.
DECLARE
v_last_code f_shifts.code%TYPE;
TYPE t_tbl IS TABLE OF f_shifts.code%TYPE;
-- Above line creates the nested table type of the required type.
v_tbl T_TBL;
-- Above line creates the nested table variable.
BEGIN
SELECT code
BULK COLLECT INTO v_tbl -- collects all the values, ordered, into the nested table
FROM f_shifts
ORDER BY code;
v_last_code = v_tbl(v_tbl.LAST); -- gets the last values and puts into the variable
DBMS_OUTPUT.PUT_LINE('Last value is: ' || v_last_code);
END;
/