I want to find this count but when I execute the query it seems like it is stucked to "waiting for the query to complete" forever...any ideas?
SELECT (
SELECT COUNT(*)
FROM accidents,"Vechicles"
where "Date_of_accident"<'2010-01-01' and "Urban_or_Rural" like 'Urban' and "Age_Band_Of_Driver" like '26 - 35'
) AS count1
Because your query will select every row from the first table that matches your criteria, then for each row it will then select EVERY row from the second table that matches your criteria. This might end up being a huge number of rows that end up selected.
Here's an example:
CREATE TABLE #dumb (id INT);
CREATE TABLE #dumber (id INT);
INSERT INTO #dumb SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3;
INSERT INTO #dumber SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3;
SELECT * FROM #dumb, #dumber;
3 rows in each table, but the query selects 3 * 3 = 9 rows. Now imagine that there's 3 million rows in each table!
Related
I have a table and i would like to replicate/clone records within the same table. However i would like to do that with a condition. And the condition is i have a column called recordcount with numeric values. For example Row 1 can take on a value of recordcount say 7, then i would like my row 1 to be replicated 7 times. Row 2 could take on a value say 9 then i would like row 2 to be replicated 9 times.
Any help is appreciated. Thank you
What you can do (and I'm pretty sure it's not a best practice),
Is to hold a table with just numbers, which has rowcount that correspond to the numeric value.
Join that with your table, and project your table only.
Example:
create table nums(x int);
insert into nums select 1;
insert into nums select 2;
insert into nums select 2;
insert into nums select 3;
insert into nums select 3;
insert into nums select 3;
create table t (txt varchar(10) , recordcount int);
insert into t select 'A',1;
insert into t select 'B',2;
insert into t select 'C',3;
select t.*
from t
inner join nums
on t.recordcount = nums.x
order by 1
;
Will project:
"A",1
"B",2
"B",2
"C",3
"C",3
"C",3
In mssql-db I have a table with 5 columns.
id, 1st_t1, 1st_t2, 2nd_t1, 2nd_t2
it's single "task" with 2 parameters(t1,t2) "grouped" by person type(1st,2nd)
Is it possible to select info like this on picture in Reporting Service?:
Or the only way is divide this table on two tables for each person type?
In your report, your detail must have two rows.
On the first you will drag and drop the data of the 1st person and on the second row for the second like in the image below
Please try below query:
WITH T(ID, First_t1, First_t2, Second_t1, Second_t2)
AS
(
SELECT *
FROM
(
SELECT 1 ID, '1st_t1' First_t1, '1st_t2' First_t2, '2nd_t1' Second_t1, '2nd_t2' Second_t2
UNION
SELECT 2 ID, '1st_t1' First_t1, '1st_t2' First_t2, '2nd_t1' Second_t1, '2nd_t2' Second_t2
UNION
SELECT 3 ID, '1st_t1' First_t1, '1st_t2' First_t2, '2nd_t1' Second_t1, '2nd_t2' Second_t2
) A
)
SELECT * FROM
(
SELECT '1st person' person, Id,First_t1 t1,First_t2 t2 FROM T
union
SELECT '2nd person' person, Id,Second_t1 t1,Second_t2 t2 FROM T
) B
ORDER BY id
I have a table in MS Access with rows which have a column called "repeat"
I want to SELECT all the rows, duplicated by their "repeat" column value.
For example, if repeat is 4, then I should return 4 rows of the same values. If repeat is 1, then I should return only one row.
This is very similar to this answer:
https://stackoverflow.com/a/6608143
Except I need a solution for MS Access.
First create a "Numbers" table and fill it with numbers from 1 to 1000 (or up to whatever value the "Repeat" column can have):
CREATE TABLE Numbers
( i INT NOT NULL PRIMARY KEY
) ;
INSERT INTO Numbers
(i)
VALUES
(1), (2), ..., (1000) ;
then you can use this:
SELECT t.*
FROM TableX AS t
JOIN
Numbers AS n
ON n.i <= t.repeat ;
If repeat has only small values you can try:
select id, col1 from table where repeat > 0
union all
select id, col1 from table where repeat > 1
union all
select id, col1 from table where repeat > 2
union all
select id, col1 from table where repeat > 3
union all ....
What you can do is to retrieve the one 'unique' row and copy this row/column into a string however many copies you need from it using a for loop.
I want to insert multiple rows from one column by splitting column value. But I have to do that without cursors because of performance issues.
Every value is splitted to 6 chars length values. Then these values also splitted to 3, 1 and 2 chars length values to insert different columns in table B.
I think giving a sample will clarify my question:
Table A
ID Value
1 ABCDEFGHJKLM
2 NOPRST
3 NULL VALUE
I want to insert these values into table B like this format
Table B
ID Value1 Value2 Value3
1 ABC D EF
1 GHJ K LM
2 NOP R ST
Supposing 600(100 rows) as maximum length of value:
insert into tableB
select id, substr(value,n*6+1,3), substr(value,n*6+4,1), substr(value,n*6+5,2)
from tableA
join (select level-1 as n from dual connect by level <= 100)
on length(value) > n*6;
see Sqlfiddle.
select ID,
SUBSTR(value,number*6+1,3),
SUBSTR(value,number*6+4,1),
SUBSTR(value,number*6+5,2)
from yourtable,
(select 0 as number union select 1 union select 2 union select 3 union select 4
union select 5 union select 6) as numbers
/* etc up to the max length of your string /6 */
where LEN(value)>number*6
try this:
Please convert it to ORACLE SQL..
Even though, its using a while loop, its doing bulk inserts..and the loop is executed as per the length of maximun length of value in the table
declare #max_len int=0;
declare #counter int=0;
declare #col_index int=1;
select #max_len=MAX(len(Value)) from TableA
while (#max_len/6 > #counter)
begin
set #counter=#counter+1
Insert into TableB
select ID,substring(Value,#col_index,3),
substring(Value,#col_index+3,1),
substring(Value,#col_index+4,2)
from TableA where substring(Value,#col_index,3) is not null
set #col_index=#col_index+6
end
Sorry about the title, not sure how to describe without example. I trying to implement faceting of attributes in SQL Server 2008.
I have 2 tables. itemAttributes and facetParameters
Assume the following values in itemAttributes
id, itemId, name, value
---------------------------------------
1 1 keywords example1
2 1 keywords example2
3 2 color red
4 2 keywords example1
5 2 keywords example2
6 3 keywords example2
7 3 color red
8 3 color blue
Assume the following values in facetParameters
name value
----------------------
keywords example1
color red
I need to retrieve the (optional: distinct) itemIds where a given itemId has rows that contain all the values in facetParameters.
e.g. given the rows in facetParameters the query should return itemId 2. At the moment I would be using this in a CTE however given that they do not support a number of features I can work around this if there is no solution that works inside a CTE.
I have done a fair bit of sql over the years but this one has really stumped me and the shame is I keep thinking the answer must be simple.
You could join both tables, and use a having clause to ensure that all items match:
select ia.itemid
from #itemAttributes ia
inner join #facetParameters fp
on ia.name = fp.name
and ia.value = fp.value
group by ia.itemid
having count(distinct fp.name) =
(
select count(*) from #facetParameters
)
The count in the having clause assumes that the name uniquely identifies a row in the facetParameters table. If it doesn't, add an identity column to facetParameters, and use count(distinct id_column) instead of count(distinct fp.name).
Here's code to create the data set in the question:
declare #itemAttributes table (id int, itemId int,
name varchar(max), value varchar(max))
insert into #itemAttributes
select 1,1,'keywords','example1'
union all select 2,1,'keywords','example2'
union all select 3,2,'color','red'
union all select 4,2,'keywords','example1'
union all select 5,2,'keywords','example2'
union all select 6,3,'keywords','example2'
union all select 7,3,'color','red'
union all select 8,3,'color','blue'
declare #facetParameters table (name varchar(max), value varchar(max))
insert into #facetParameters
select 'keywords','example1'
union all select 'color','red'