I have my sql query like this
if not exists(select RowId from dbo.Cache where StringSearched = #FirstName and colName = 'FirstName')
begin
--some code here
end
The purpose of above if statement is not to execute the piece of code inside of it if value of StringSearched is already present in Cache table which means it has been looked up before and so no need to make calculations again. The code inside of if statement if executed returns row number of rows from Table Band those are then inserted into Cache table to continue maintaining the cache. anyway .I need the records to be picked from Cache only if ModifiedAt column of Cache table is latest than ModifiedAt column of rows of Table B.
Note: I understand that I may need to use a subquery in where clause but in where clause itself, I need to check ModifiedAt column of Table B only for RowId's returned by Outer select query .
How can I proceed without making it much complex ?
You can use the subquery in the current query along with the Where clause.You didn't specified what are the columns to know for figure out which rows to get value so I assumed your tableB also has StringSearched and colName to get max(ModifiedAt) for that string vlaue.
IF NOT EXISTS (SELECT * from dbo.Cache as c WHERE StringSearched = #FirstName
AND colName = 'FirstName'
AND ModifiedAt > (Select MAX(ModifiedAt) FROM tableB as tabB WHERE tabB.RowID = c.RowID ))
BEGIN
--your query
END
Related
I have removed rows from a results table after it has been built already. I have decided to try to remove the rows from being inserted into the results table in the first place instead.
To remove the appropriate rows from the results table after the fact I used:
if #InterchangeAction = 'HCR'
begin
--Do not allow claims to be output if they have a prior submission marked 'output'
--and the interchange 'output submission action' is marked as 'hold'
delete from #ResultSet
where exists ( select 1 from ClaimSubmissions CS inner join InterchangeInfo I on CS.InterchangeId = I.InterchangeId
where #ResultSet.ClaimId = CS.ClaimId
and CS.InterchangeId = #InterchangeID
and CS.SubmissionStatus = 'OPT'
and CS.OutputDate is not NULL
)
end
This works as I want but I am thinking it would be more efficient to stop the rows from being added in the first place.
I'm going to start my check with:
if #InterchangeAction = 'HCR'
and then concatenate on to the existing where clause but I am unsure on how to convert the delete statement into a where clause?
Any pointers on where to start would be greatly appreciated.
Unless I'm missing something obvious, aren't you just looking for this?:
INSERT #ResultSet
(<Column List>)
SELECT
<Column List>
FROM
WhatHaveYou AS WHY
WHERE NOT EXISTS ( select 1 from ClaimSubmissions CS
inner join InterchangeInfo I
on CS.InterchangeId = I.InterchangeId
where WHY.ClaimId = CS.ClaimId
and CS.InterchangeId = #InterchangeID
and CS.SubmissionStatus = 'OPT'
and CS.OutputDate is not NULL
)
I got a table Table(id,name), but lets just work with id here
id
--
A
B
C
D
all
What I want is to select all rows (A,B,C D...) except 'all' if the input is all, otherwise only the specific value ( e.g.: A if the input is A ).
Do you guys have some tasty-juicy solution for this one? Thanks!
Let's say you have a parameter #Id in your query. Then you can formulate your WHERE clause based on #Id's value:
SELECT *
FROM MyTable t
WHERE i.Id <> 'all' AND (#Id='all' OR #Id=t.Id)
i.Id <> 'all' part ensures that 'all' row is never returned, regardless of the setting of #Id. The rest is your condition translated to SQL (i.e. either the query has 'all', or the query matches a single Id).
This looks like the wrong usage of a relational table as the "id" column should contain only ids...
I suggest removing the "all" row and instead write a stored procedure to decide whether to select all rows or just one.
Anyway, for your example:
SELECT * FROM your_table WHERE (id = #ID OR #ID = 'all') AND id <> 'all'
I have one table with the following columns:
T_RESOLVED_DATE
I_HOUSEHOLD_NUMBER
I_RESOLVED_SET_NUMBER
I_STATION_CODE
I_RESOLVED_START_MIN
I_DURATION
I_PERSON_NUMBER
I_COVIEW_DEMO_ID
Initially, I_COVIEW_DEMO_ID is set to null.
Then I have another table with the following columns:
T_RESOLVED_DATE
I_HOUSEHOLD_NUMBER
I_PERSON_NUMBER
I_AGE
T_GENDER
I_COVIEW_DEMO_ID
I am trying to update I_COVIEW_DEMO_ID in the first table by using the value of I_COVIEW_DEMO_ID in the second table where the T_RESOLVED_DATE, I_HOUSEHOLD_NUMBER, and I_PERSON_NUMBER are equal in both tables. The first table may contain multiple rows with the same DATE, HOUSEHOLD_NUMBER, and PERSON_NUMBER, because the rows can vary by the rest of the columns.
I have tried to do a select and a group by which seems to get me part way there, but I am getting a "single-row subquery returns more than one row" error when I try to update the columns in the first table. This is what I've tried, along with variations of it:
UPDATE
Table1
SET
I_COVIEW_DEMO_ID =
(SELECT
b.I_COVIEW_DEMO_ID
FROM Table1 a,
Table2 b
WHERE a.I_HOUSEHOLD_NUMBER = b.I_HOUSEHOLD_NUMBER AND
a.I_PERSON_NUMBER = b.I_PERSON_NUMBER AND
a.T_RESOLVED_DATE = b.T_RESOLVED_DATE
GROUP BY b.I_COVIEW_DEMO_ID);
Any suggestions?
I was able to get it to work using this statement:
MERGE INTO table1 a
USING
(
SELECT DISTINCT
T_RESOLVED_DATE,
I_HOUSEHOLD_NUMBER,
I_PERSON_NUMBER,
I_COVIEW_DEMO_ID
FROM
table2
) b
ON
(
a.T_RESOLVED_DATE = b.T_RESOLVED_DATE
AND a.I_HOUSEHOLD_NUMBER = b.I_HOUSEHOLD_NUMBER
AND a.I_PERSON_NUMBER = b.I_PERSON_NUMBER
) WHEN MATCHED THEN
UPDATE SET
a.I_COVIEW_DEMO_ID = b.I_COVIEW_DEMO_ID;
As per our discussion on the comments this would be a simple PLSQL block to do what you need. I'm doing direct from my head without test, so you may need to fix some sintaxe mistake.
BEGIN
FOR rs IN ( SELECT I_HOUSEHOLD_NUMBER,
I_PERSON_NUMBER,
I_COVIEW_DEMO_ID,
T_RESOLVED_DATE
FROM Table2 ) LOOP
UPDATE Table1
SET I_COVIEW_DEMO_ID = rs.I_COVIEW_DEMO_ID
WHERE I_PERSON_NUMBER = rs.I_PERSON_NUMBER
AND I_HOUSEHOLD_NUMBER = rs.I_HOUSEHOLD_NUMBER
AND T_RESOLVED_DATE = rs.T_RESOLVED_DATE;
END LOOP;
--commit after all updates, if there is many rows you should consider in
--making commits by blocks. Define a count and increment it whithin the for
--after some number of updates you commit and restart the counter
COMMIT;
END;
If I create a VIEW using this pivot table query, it isn't editable. The cells are read-only and give me the SQL2005 error: "No row was updated. The data in row 2 was not committed. Update or insert of view or function 'VIEWNAME' failed because it contains a derived or constant field."
Any ideas on how this could be solved OR is a pivot like this just never editable?
SELECT n_id,
MAX(CASE field WHEN 'fId' THEN c_metadata_value ELSE ' ' END) AS fId,
MAX(CASE field WHEN 'sID' THEN c_metadata_value ELSE ' ' END) AS sID,
MAX(CASE field WHEN 'NUMBER' THEN c_metadata_value ELSE ' ' END) AS NUMBER
FROM metadata
GROUP BY n_id
Assuming you have a unique constraint on n_id, field which means that at most one row can match you can (in theory at least) use an INSTEAD OF trigger.
This would be easier with MERGE (but that is not available until SQL Server 2008) as you need to cover UPDATES of existing data, INSERTS (Where a NULL value is set to a NON NULL one) and DELETES where a NON NULL value is set to NULL.
One thing you would need to consider here is how to cope with UPDATES that set all of the columns in a row to NULL I did this during testing the code below and was quite confused for a minute or two until I realised that this had deleted all the rows in the base table for an n_id (which meant the operation was not reversible via another UPDATE statement). This issue could be avoided by having the VIEW definition OUTER JOIN onto what ever table n_id is the PK of.
An example of the type of thing is below. You would also need to consider potential race conditions in the INSERT/DELETE code indicated and whether you need some additional locking hints in there.
CREATE TRIGGER trig
ON pivoted
INSTEAD OF UPDATE
AS
BEGIN
SET nocount ON;
DECLARE #unpivoted TABLE (
n_id INT,
field VARCHAR(10),
c_metadata_value VARCHAR(10))
INSERT INTO #unpivoted
SELECT *
FROM inserted UNPIVOT (data FOR col IN (fid, sid, NUMBER) ) AS unpvt
WHERE data IS NOT NULL
UPDATE m
SET m.c_metadata_value = u.c_metadata_value
FROM metadata m
JOIN #unpivoted u
ON u.n_id = m.n_id
AND u.c_metadata_value = m.field;
/*You need to consider race conditions below*/
DELETE FROM metadata
WHERE NOT EXISTS(SELECT *
FROM #unpivoted u
WHERE metadata.n_id = u.n_id
AND u.field = metadata.field)
INSERT INTO metadata
SELECT u.n_id,
u.field,
u.c_metadata_value
FROM #unpivoted u
WHERE NOT EXISTS (SELECT *
FROM metadata m
WHERE m.n_id = u.n_id
AND u.field = m.field)
END
You'll have to create trigger on view, because direct update is not possible:
CREATE TRIGGER TrMyViewUpdate on MyView
INSTEAD OF UPDATE
AS
BEGIN
SET NOCOUNT ON;
UPDATE MyTable
SET ...
FROM INSERTED...
END
I use a cursor to iterate through quite a big table. For each row I check if value from one column exists in other.
If the value exists, I would like to increase value column in that other table.
If not, I would like to insert there new row with value set to 1.
I check "if exists" by:
IF (SELECT COUNT(*) FROM otherTabe WHERE... > 1)
BEGIN
...
END
ELSE
BEGIN
...
END
I don't know how to get that row which was found and update value. I don't want to make another select.
How can I do this efficiently?
I assume that the method of checking described above isn't good for this case.
Depending on the size of your data and the actual condition, you have two basic approaches:
1) use MERGE
MERGE TOP (...) INTO table1
USING table2 ON table1.column = table2.column
WHEN MATCHED
THEN UPDATE SET table1.counter += 1
WHEN NOT MATCHED SOURCE
THEN INSERT (...) VALUES (...);
the TOP is needed because when you're doing a huge update like this (you mention the table is 'big', big is relative, but lets assume truly big, +100MM rows) you have to batch the updates, otherwise you'll overwhelm the transaction log with one single gigantic transaction.
2) use a cursor, as you are trying. Your original question can be easily solved, simply always update and then check the count of rows updated:
UPDATE table
SET column += 1
WHERE ...;
IF ##ROW_COUNT = 0
BEGIN
-- no match, insert new value
INSERT INTO (...) VALUES (...);
END
Note that this approach is dangerous though because of race conditions: there is nothing to prevent another thread from inserting the value concurrently, so you may end up with either duplicates or a constraint violation error (preferably the latter...).
This is just psuedo code because I have no idea of your table structure but I think you will understand... basically Update the columns you want then Insert the columns you need. A Cursor operation sounds unnecessary.
Update OtherTable
Set ColumnToIncrease = ColumnToIncrease + 1
FROM CurrentTable Where ColumnToCheckValue is not null
Insert Into OtherTable (ColumnToIncrease, Field1, Field2,...)
SELECT
1,
?
?
FROM CurrentTable Where ColumnToCheckValue is not null
Without a sample, I think this is the best I can do. Bottom line: you don't need a cursor. UPDATE where a match exists (INNER JOIN) and INSERT where one does not.
UPDATE otherTable
SET IncrementingColumn = IncrementingColumn + 1
FROM thisTable INNER JOIN otherTable ON thisTable.ID = otherTable.ID
INSERT INTO otherTable
(
ID
, IncrementingColumn
)
SELECT ID, 1
FROM thisTable
WHERE NOT EXISTS (SELECT *
FROM otherTable
WHERE thisTable.ID = otherTable.ID)
I think you'd be better off using a view for this -- then it's always up to date, no risk of mistakenly double/triple/etc counting:
CREATE VIEW vw_value_count AS
SELECT st.value,
COUNT(*) AS numValue
FROM SOME_TABLE st
GROUP BY st.value
But if you still want to use the INSERT/UPDATE approach:
IF EXISTS(SELECT NULL
FROM SOMETABLE WHERE ... > 1)
BEGIN
UPDATE TABLE
SET count = count + 1
WHERE value = #value
END
ELSE
BEGIN
INSERT INTO TABLE
(value, count)
VALUES
(#value, 1)
END
What about Update statement with inner join to perform +1, and Insert selected rows that do not exist in the first table.
Provide the tables schema and the columns you want to check and update so I can help.
Regards.