My english won't help to explain what my problem is but i will give a try.
Lets say we have a table with (photoId, _bandId, desc)
Now we have a set of records
1, 1000, TestDesc1
2, 1000, TestDesc2
3, 1010, TestDesc3
4, 1900, TestDesc4
5, 1000, TestDesc5
Im trying to find a select command where gets all the [desc] for a specific [_bandId]
BUT AS FIRST RESULT i want a specific photoId
What i use,
SELECT * FROM [myTable]
WHERE _bandId = (SELECT _bandId from [myTable] where photoId=2)
This of course gives me as output :
TestDesc1
TestDesc2
TestDesc5
BUT what i really need as output is this
TestDesc2
TestDesc1
TestDesc5
Kind Regards
Konstantinos
Add an order by with a case as the first parameter, where you create a value that is 0 for the record that you want first and 1 for the other records. After that you can add more parameters for how you want to sort the remaing records, for example on description:
SELECT
*
FROM
[myTable]
WHERE
_bandId = (SELECT _bandId from [myTable] where photoId=2)
ORDER BY
CASE PhotoId WHEN 2 THEN 0 ELSE 1 END,
[desc]
Related
it is possible do a SELECT CASE, decode, nvl or another query function when I need verify if the return of a select query is empty or has a value?
For example, I have this:
Record | type | id_customer
-------+--------+-------------
1 | T | cus1
2 | A | cus2
3 | T | cus3
4 | | cus4
If I do this:
select decode(type,'T','Main','A','Adicional','none') from table where record=1;
I get Main.
If I fo this:
select decode(type,'T','Main','A','Adicional','none') from table where record=4;
I get none.
But if I do this:
select decode(type,'T','Main','A','Aditional','none') from table where record=5;
I get nothing, and is logic. So, I need get the decode value when the row exist and a text if the rows no exist.
So, I tried with SELECT CASE but is not posible get a value using COUNT. For example like this:
SELECT
CASE
WHEN count(1)>0 THEN decode(type,'T','Main','A','Aditional','none')
ELSE '-'
END
FROM TABLE WHERE record=5;
And get a ' - ', or the same if the record is 2, get 'Aditional'
Thanks a lot.
You can use aggregate functions min or max outside expression:
select max(decode(type,'T','Main','A','Aditional','none'))
from table
where record=5;
If query returns one row, you get value of that row. If query returns 0 rows, you get NULL.
Then you can replace NULL using nvl:
select nvl(max(decode(type,'T','Main','A','Aditional','none')), ' - ')
from table
where record=5;
EDIT
Also, if you need to choose one string from several:
select decode(max(decode(type,'T', 2, 'A', 1, 0)), 0, 'none', 1, 'Additional', 2, 'Main', null, ' - ')
from table
where record=5;
This is an option:
select decode(type,'T','Main','A','Aditional','none')
from table
where record = 5
union all
select '-'
from dual
where not exists (select 1 from table where record = 5);
It selects records with record = 5 and unifies them with '-', if no records exits with record = 5. Check out this Fiddle.
I can not figure out how to query a SQLite.
needed:
1) Replace the record (the primary key), if the condition (comparison of new and old fields entries)
2) Insert an entry if no such entry exists in the database on the primary key.
Importantly, it has to work very fast!
I can not come up with an effective inquiry.
Edit.
MyInsertRequest - the desired expression.
Script:
CREATE TABLE testtable (a INT PRIMARY KEY, b INT, c INT)
INSERT INTO testtable VALUES (1, 2, 3)
select * from testtable
1|2|3
-- Adds an entry, because the primary key is not
++ MyInsertRequest VALUES (2, 2, 3) {if c>4 then replace}
select * from testtable
1|2|3
2|2|3
-- Adds
++ MyInsertRequest VALUES (3, 8, 3) {if c>4 then replace}
select * from testtable
1|2|3
2|2|3
3|8|3
-- Does nothing, because such a record (from primary key field 'a')
-- is in the database and none c>4
++ MyInsertRequest VALUES (1, 2, 3) {if c>4 then replace}
select * from testtable
1|2|3
2|2|3
3|8|3
-- Does nothing
++ MyInsertRequest VALUES (3, 34, 3) {if c>4 then replace}
select * from testtable
1|2|3
2|2|3
3|8|3
-- replace, because such a record (from primary key field 'a')
-- is in the database and c>2
++ MyInsertRequest VALUES (3, 34, 1) {if c>2 then replace}
select * from testtable
1|2|3
2|2|3
3|34|1
Isn't INSERT OR REPLACE what you need ? e.g. :
INSERT OR REPLACE INTO table (cola, colb) values (valuea, valueb)
When a UNIQUE constraint violation occurs, the REPLACE algorithm
deletes pre-existing rows that are causing the constraint violation
prior to inserting or updating the current row and the command
continues executing normally.
You have to put the condition in a unique constraint on the table. It will automatically create an index to make the check efficient.
e.g.
-- here the condition is on columnA, columnB
CREATE TABLE sometable (columnPK INT PRIMARY KEY,
columnA INT,
columnB INT,
columnC INT,
CONSTRAINT constname UNIQUE (columnA, columnB)
)
INSERT INTO sometable VALUES (1, 1, 1, 0);
INSERT INTO sometable VALUES (2, 1, 2, 0);
select * from sometable
1|1|1|0
2|1|2|0
-- insert a line with a new PK, but with existing values for (columnA, columnB)
-- the line with PK 2 will be replaced
INSERT OR REPLACE INTO sometable VALUES (12, 1, 2, 6)
select * from sometable
1|1|1|0
12|1|2|6
Assuming your requirements are:
Insert a new row when a doesn't exists;
Replacing row when a exist and existing c greater then new c;
Do nothing when a exist and existing c lesser or equal then new c;
INSERT OR REPLACE fits first two requirements.
For last requirement, the only way I know to make an INSERT ineffective is supplying a empty rowset.
A SQLite command like following whould make the job:
INSERT OR REPLACE INTO sometable SELECT newdata.* FROM
(SELECT 3 AS a, 2 AS b, 1 AS c) AS newdata
LEFT JOIN sometable ON newdata.a=sometable.a
WHERE newdata.c<sometable.c OR sometable.a IS NULL;
New data (3,2,1 in this example) is LEFT JOINen with current table data.
Then WHERE will "de-select" the row when new c is not less then existing c, keeping it when row is new, ie, sometable.* IS NULL.
I tried the others answers because I was also suffering from a solution to this problem.
This should work, however I am unsure about the performance implications. I believe that you may need the first column to be unique as a primary key else it will simply insert a new record each time.
INSERT OR REPLACE INTO sometable
SELECT columnA, columnB, columnC FROM (
SELECT columnA, columnB, columnC, 1 AS tmp FROM sometable
WHERE sometable.columnA = 1 AND
sometable.columnB > 9
UNION
SELECT 1 AS columnA, 1 As columnB, 404 as columnC, 0 AS tmp)
ORDER BY tmp DESC
LIMIT 1
In this case one dummy query is executed and union-ed onto a second query which would have a performance impact depending on how it is written and how the table is indexed. The next performance problem has potential where the results are ordered and limited. However, I expect that the second query should only return one record and therefore it should not be too much of a performance hit.
You can also omit the ORDER BY tmp LIMIT 1 and it works with my version of sqlite, but it may impact performance since it can end up updating the record twice (writing the original value then the new value if applicable).
The other problem is that you end up with a write to the table even if the condition states that it should not be updated.
I am using following query in which , table which is being referred that have 50Million+ records. By creating history table will help me out to better CPU performance ? or is there any other option apart from Partition. Or Query plan tweak is the only option ?
SELECT MIN(minbkt),
maxbkt,
SUBSTRB(DUMP(MIN(val), 16, 0, 32), 1, 120) minval,
SUBSTRB(DUMP(MAX(val), 16, 0, 32), 1, 120) maxval,
SUM(rep) sumrep,
SUM(repsq) sumrepsq,
MAX(rep) maxrep,
COUNT(*) bktndv,
SUM(CASE
WHEN rep = 1 THEN
1
ELSE
0
END) unqrep
FROM (SELECT val,
MIN(bkt) minbkt,
MAX(bkt) maxbkt,
COUNT(val) rep,
COUNT(val) * COUNT(val) repsq
FROM (SELECT
/*+ no_parallel(t) no_parallel_index(t) dbms_stats cursor_sharing_exact use_weak_name_resl dynamic_sampling(0) no_monitoring */
"VERSION_LABEL" val,
NTILE(75) OVER(ORDER BY NLSSORT("VERSION_LABEL", 'NLS_SORT = binary')) bkt
FROM "User"."AUDITTRAIL" t
WHERE "VERSION_LABEL" IS NOT NULL)
GROUP BY val)
GROUP BY maxbkt
ORDER BY maxbkt
It looks like this is a query associated with gathering a histogram on the version_label column of an auditing table.
I would expect that you almost certainly do not need such a histogram to be present, and you can modify the statistics gathering to just collect simple statistics on such a table -- ie. no histograms. the best way of doing that would be based on your version and the way in which the statistics gathering is being triggered, but if you need help with that then either expand the question to include those details or start another question.
I am trying to build a query which will do this:
Lets say for example I have 100 records in the table. I have .net form which calls the query. I have a querystring parameter pageindex, something like http://mysite.com?id=2.
What I want to do now is if id = NULL, then get the 1st set of records from that table whichave id of 1 to 20, means from 1 to 20, if id=2 then get the 2nd set of recordw, from row 20 to 40, if id=3 then get the 3rd set of records, meaning records from 40 to 60, from that table.
I want to know if this is possible.
Thanks a lot in advance, Laziale
If you make it as you say so, and the IDs are in line from 1 to 100 you can do
#Page is the page number (base on 0)
SELECT TOP 20 * FROM MyTable WHERE (ID > #Page*20) ORDER BY ID
If you wish to use the paging style of Ms SQL and the ids are not in line you can do
WITH NewTable AS (SELECT *, ROW_NUMBER() OVER (ORDER BY ID) AS RowNumber FROM MyTable)
SELECT TOP 20 * FROM NewTable WHERE (RowNumber > #Page*20)
Reference :
http://msdn.microsoft.com/en-us/library/ms186734.aspx
http://msdn.microsoft.com/en-us/library/ms175972.aspx
SELECT col1, col2
FROM (
SELECT col1, col2, ROW_NUMBER() OVER (ORDER BY ID) AS RowNum
FROM MyTable
) AS MyDerivedTable
WHERE MyDerivedTable.RowNum BETWEEN #startRow AND #endRow
taken from Row Offset in SQL Server, first result in google via "mssql limit offset" search queue.
I have an column in table where this column name is items it contains value like this
itemID items
1 school,college
2 place, country
3 college,cricket
4 School,us,college
5 cricket,country,place
6 football,tennis,place
7 names,tennis,cricket
8 sports,tennis
Now I need to write a search query
Ex: if the user types 'cricket' into a textbox and clicks the button I need to check in the column items for cricket.
In the table I have 3 rows with cricket in the items column (ItemId = 3, 5, 7)
If the user types in tennis,cricket then I need to get the records that match either one. So I need to get 5 row (ItemId = 3, 5, 6, 7, 8)
How do I write a query for this requirement?
You need to start by redesigning your database as this is is a very bad structure. You NEVER store a comma delimited list in a field. First think about waht fields you need and then design a proper database.
The very bad structure of this table (holding multiple values in one column) is the reason you are facing this issue. Your best option is to normalize the table.
But if you can't, then you can use the "Like" operator, with a wildcard
Select * From Table
Where items Like '%cricket%'
or
Select * From Table
Where items Like '%cricket%'
or items Like '%tenis%'
You will need to dynamically construct these sql queries from the inputs the user makes. The other alternative is to write code on the server to turn the comma delimited list of parameters into a table variable or temp table and then join to it..
Delimited values in columns is almost always a bad table design. Fix your table structure.
If for some reason you are unable to do that, the best you can hope for is this:
SELECT * FROM [MyTable] WHERE items LIKE '%CRICKET%'
This is still very bad, for two important reasons:
Correctness. It would return values that only contain the word cricket. Using your tennis example, what if you also had a "tennis shoes" item?
Performance. It's not sargable, which means the query won't work with any indexes you may have on that column. That means your query will probably be incredibly slow.
If you need help fixing this structure, the solution is to add another table — we'll call it TableItems — with a column for your ItemID that will be a foreign key to your original table and an item field (singular) for each of your item values. Then you can join to that table and match a column value exactly. If these items work more like categories, where you want to rows with the "Cricket" item to match the same cricket item, you also want a third table to be an intersection between your original table and the other one I just had you create.
For a single item:
SELECT itemID, items FROM MyTable WHERE items LIKE '%cricket%'
For multiple items:
SELECT itemID, items FROM MyTable WHERE items LIKE '%tennis%' or items LIKE '%cricket%'
You'll need to parse the input and split them up and add each item to the query:
items LIKE '%item1%' or items LIKE '%item2%' or items LIKE '%item3%' ...
I think that in the interest of validity of data, it should be normalized so that you split the Items into a separate table with an item on each row.
In either case, here is a working sample that uses a user defined function to split the incoming string into a Table Variable and then uses JOIN with a LIKE
CREATE FUNCTION dbo.udf_ItemParse
(
#Input VARCHAR(8000),
#Delimeter char(1)='|'
)
RETURNS #ItemList TABLE
(
Item VARCHAR(50) ,
Pos int
)
AS
BEGIN
DECLARE #Item varchar(50)
DECLARE #StartPos int, #Length int
DECLARE #Pos int
SET #Pos = 0
WHILE LEN(#Input) > 0
BEGIN
SET #StartPos = CHARINDEX(#Delimeter, #Input)
IF #StartPos < 0 SET #StartPos = 0
SET #Length = LEN(#Input) - #StartPos - 1
IF #Length < 0 SET #Length = 0
IF #StartPos > 0
BEGIN
SET #Pos = #Pos + 1
SET #Item = SUBSTRING(#Input, 1, #StartPos - 1)
SET #Input = SUBSTRING(#Input, #StartPos + 1, LEN(#Input) - #StartPos)
END
ELSE
BEGIN
SET #Pos = #Pos+1
SET #Item = #Input
SET #Input = ''
END
INSERT #ItemList (Item, Pos) VALUES(#Item, #Pos)
END
RETURN
END
GO
DECLARE #Itemstable TABLE
(
ItemId INT,
Items VarChar (1000)
)
INSERT INTO #Itemstable
SELECT 1 itemID, 'school,college' items UNION
SELECT 2, 'place, country' UNION
SELECT 3, 'college,cricket' UNION
SELECT 4, 'School,us,college' UNION
SELECT 5, 'cricket,country,place' UNION
SELECT 6, 'footbal,tenis,place' UNION
SELECT 7, 'names,tenis,cricket' UNION
SELECT 8, 'sports,tenis'
DECLARE #SearchParameter VarChar (100)
SET #SearchParameter = 'cricket'
SELECT DISTINCT ItemsTable.*
FROM #Itemstable ItemsTable
INNER JOIN udf_ItemParse (#SearchParameter, ',') udf
ON ItemsTable.Items LIKE '%' + udf.Item + '%'
SET #SearchParameter = 'cricket,tenis'
SELECT DISTINCT ItemsTable.*
FROM #Itemstable ItemsTable
INNER JOIN udf_ItemParse (#SearchParameter, ',') udf
ON ItemsTable.Items LIKE '%' + udf.Item + '%'
Why exactly are you using a database in the first place?
I mean : you are clearly not using it's potential. If you like using comma separated stuff, try a file.
In MySQL, create a fulltext index on your table:
CREATE FULLTEXT INDEX fx_mytable_items ON mytable (items)
and issue this query:
SELECT *
FROM mytable
WHERE MATCH(items) AGAINST ('cricket tennis' IN BOOLEAN MODE)