One way to set a value constraint is to use a database check constraint:
balance integer CHECK (balance > 0)
Is it possible to declare the constraint during an update, for example:
UPDATE xx SET balance = balance + 1000 WHERE user_id=$1 CHECK balance > $2
And be able to do this within one query.
You can add a hack assert. For SQL Server this would be:
UPDATE xx
SET balance = balance + 1000
WHERE user_id=$1
AND IIF((balance + 1000) > $2, 0, 0/0) = 0
This causes a division by zero error in case there is a problem. It's a big hack, but it can be useful as an inline assertion.
Related
When I run my query, it prints multiple execution times instead of just one. I only want one so what do I need to do to get this to only print one time stamp?
SET STATISTICS TIME ON
DECLARE #firstNum INT, #secondNum INT, #thirdNum INT, #evenSum INT
SET #firstNum = 1
SET #secondNum = 2
set #thirdNum = 2
SET #evenSum = 2
WHILE (#thirdNum <= 4000000)
BEGIN
SET #thirdNum = #firstNum + #secondNum
SET #firstNum = #secondNum
SET #secondNum = #thirdNum
IF (#thirdNum % 2) = 0
SET #evenSum += #thirdNum
END
PRINT 'Answer = ' + CONVERT(VARCHAR, #evenSum)
SET STATISTICS TIME OFF
If you remove PRINT 'Answer = ' + CONVERT(VARCHAR, #evenSum) from your code
then it won't print multiple execution time.
Here is the example of it.
Statistic time will print for each execution. Since you are looping you are performing multiple query statements (I believe this also applies for sets -i could be wrong though), each will provide an execution time. There really is no way to modify statistic time for what I think you are looking for.
You could declare a datetime2 and store the start time in the beginning by using SysDateTime, and get the end time upon completion, thus printing the difference onto the screen using DateDiff. (This will achieve what you are asking for. )
You could also look into client statistic (but that might not be what you want).
Side note and irrelevant: you are looping queries. This is not profient and you may be doing this to learn. I would recommend looking into Tally tables for replacing loops. You can greatly improve performance if you design your query correctly.
I am trying to find the (best) way to update column of table based on calculated another column.
First of all, I am using function to calculate value for 'BAS_CBR_EB_RWA' column and then I am using 'BAS_CBR_EB_RWA' value as an input for 'BAS_CBR_EB_TOTAL_CAPITAL' column calculation, as shown in below-mentioned code.
Could you please share how to reuse it to do next calculation. replacing 'BAS_CBR_EB_RWA' with right-hand calculation isn't desirable because we have too many calculation of this type and it'll confuse other users.
Thanks in advance for help.
IF INSTTABLE = 16 THEN
UPDATE LAO_DATA
SET BAS_CBR_EB_RWA = BAS2_RWA_CALC(BAS_CAPITAL_CALC_CD,
CBR_CUR_BOOK_BAL,
BAS_CAP_FACTOR_K,
V_BASEL_MIN,
V_BAS_RWA_RATE),
BAS_CBR_EB_TOTAL_CAPITAL = ROUND(BAS2_MGRL_CAPITAL(V_DATE,
BAS_CBR_EB_RWA,
0),
2),
WHERE (AS_OF_DATE = V_DATE);
--COMMIT;
END IF;
In Oracle, you can update a subquery. I'm not 100% sure if it works for UDFs, but you can try:
UPDATE (SELECT LD.*,
BAS2_RWA_CALC(BAS_CAPITAL_CALC_CD, CBR_CUR_BOOK_BAL, BAS_CAP_FACTOR_K, V_BASEL_MIN, V_BAS_RWA_RATE) as new_BAS_CBR_EB_RWA
FROM LAO_DATA LD
)
SET BAS_CBR_EB_RWA = new_BAS_CBR_EB_RWA,
BAS_CBR_EB_TOTAL_CAPITAL = ROUND(BAS2_MGRL_CAPITAL(V_DATE, nw_BAS_CBR_EB_RWA, 0), 2),
WHERE AS_OF_DATE = V_DATE;
A MERGE statement can be used. You may also replace ROWID with the primary key or a Unique key of the table.
Put all your first level of calculations with function calls inside the USING() block and the second level of calculation for RHS in the SET expression
MERGE INTO lao_data t
USING (
SELECT ROWID AS rid,bas2_rwa_calc(bas_capital_calc_cd,
cbr_cur_book_bal,
bas_cap_factor_k,
v_basel_min,v_bas_rwa_rate
) AS new_BAS_CBR_EB_RWA
FROM lao_data
WHERE as_of_date = V_DATE
)
s ON ( s.rid = t.rowid )
WHEN MATCHED THEN UPDATE
SET t.bas_cbr_eb_rwa = s.new_BAS_CBR_EB_RWA
t.bas_cbr_eb_total_capital
= round(bas2_mgrl_capital(v_date,s.nw_BAS_CBR_EB_RWA,0), 2) );
I know this is already asked question and possible to be close.
But i really want a answer, I already searched through the internet, Read documentations, Blogs, and Question to SO.
This is my Query so Far,
declare #count numeric
select #count = (select count(1) from E496_TitleReference a where
exists (select 1 from #tempTransactions b where a.EPEB_RoD = b.tEPEB_RoD and
a.EPEB_ENO = b.tEPEB_ENO and a.EPEB_ID = b.tEPEB_ID and a.Title_Seq = b.tTitle_Seq))
update E496_TitleReference
set PrintStatus = '{0}',Is_AESM=isnull(-1,Is_AESM)
from E496_TitleReference a where
exists (select 1 from #tempTransactions b where a.EPEB_RoD = b.tEPEB_RoD and
a.EPEB_ENO = b.tEPEB_ENO and a.EPEB_ID = b.tEPEB_ID and a.Title_Seq = b.tTitle_Seq)
if ##rowcount <> #count
begin
rollback tran
Print "Error: There is an error on table E496_TitleReference."
return
end
go
For eg, In my table in Database i have column name Is_AESM, In Is_AESM column it have 4 values.
Is_AESM
NULL
NULL
-1
-2
Something like this.
Now when i run my script, it has no problem when i run it,
Is_AESM=isnull(-1,Is_AESM)
In this query it will detect if Is_AESM is null, it will update Is_AESM = -1 if not it will retain the value.
Now my problem is, if my query detect Is_AESM has a null value, it will update all the value to -1.
Is_AESM
-1
-1
-1
-1
The result is something like that. Now i want is update only the null value not all the value in column Is_AESM.
I think this query is wrong Is_AESM=isnull(-1,Is_AESM).
Any ideas will be a big help.
You may try with coalsece() function
update E496_TitleReference
set PrintStatus = '{0}',Is_AESM=coalsece(Is_AESM,-1)
from E496_TitleReference a where
exists (select 1 from #tempTransactions b where a.EPEB_RoD = b.tEPEB_RoD and
a.EPEB_ENO = b.tEPEB_ENO and a.EPEB_ID = b.tEPEB_ID and a.Title_Seq = b.tTitle_Seq)
you need to replace order of parameters.
Is_AESM=isnull(Is_AESM, -1)
You can use COALSECE function. It returns the first non-null entry from the given list. So:
Is_AESM= COALSECE(IS_AESM,-1)
This will return IS_AESM value if it is not null (since it is the first non-null value)
Else if IS_AESM is NULL then it returns -1 (since it is the non-null value)
I have this statement
UPDATE table SET health = health + 1 WHERE name='Tom'
How can I set a MAX for the number field in the statement based off? Pseudo code:
UPDATE table set health = min(health+1, max_health) WHERE name='Tom'
The simplest way is to modify the where:
UPDATE table
SET health = health + 1
WHERE name = 'Tom' AND health < max_health;
Some databases support the least() function:
UPDATE table
SET health = LEAST(health + 1, max_health)
WHERE name = 'Tom' ;
You can also do this using CASE.
However, I think the first method is the simplest.
We can use CASE also
UPDATE table
SET health = (CASE WHEN health+1 < max_health THEN
health+1
ELSE
max_health
END) WHERE name='Tom'
AND IIF --SQL Server
UPDATE table SET health = IIF (health+1 < max_health, health+1, max_health) WHERE name='Tom'
Given a table, for example Article(Id,Body,Revisions), I would like to increment the Revisions attribute, and, once a certain limit is reached (it's a constant provided by the developer), an error should be thrown. Is this possible to achieve with a single UPDATE ... SET statement in T-SQL?
What I've done:
To increment Revisions attribute by one, I solved as shown here: Is UPDATE command thread safe (tracking revisions) in MS SQL.
Problem
To find a way that is thread safe, which would allow incrementation of Revisions until a certain upper bound is reached.
Context
Since I'm using EF, the ideal solution would be to either thrown an error or specify a flag of some sort. The code I'm using (shown below) is encapsulated into a try-catch:
context.Database.ExecuteSqlCommand("UPDATE dbo.Articles SET Revisions = Revisions + 1 WHERE Id=#p0;", articleId);
You could do this with a WHERE clause in your UPDATE statement, which would do the test. If the test fails, the update will not happen and your call with context.Database.ExecuteSqlCommand will return 0 instead of 1.
In case of a limit of 1000, the update SQL would be:
count = context.Database.ExecuteSqlCommand(
"UPDATE dbo.Articles SET Revisions = Revisions + 1 WHERE Id=#p0 AND Revisions < 1000;", articleId);
Then afterwards you would test whether count == 0 and raise an error message if so.
Use a CHECK constraint. No update statement can violate bounds that are implemented by a CHECK constraint. Not even an update statement issued by a sleep-deprived DBA at the console.
create table article (
id integer primary key,
body nvarchar(max) not null,
-- Allow six versions. (Original plus five revisions.)
revisions integer not null
check (revisions between 0 and 5)
);
insert into article values (1, 'a', 0);
update article
set body = 'b', revisions = 1
where id = 1;
update article
set body = 'c', revisions = 2
where id = 1;
-- Other updates . . .
-- This update will *always* fail with an error.
update article
set body = 'f', revisions = 6
where id = 1;
Kind of whacked but
UPDATE dbo.Articles
SET Revisions = Revisions + 1
WHERE Id=#p0
AND sqrt(Revisions - #MaxRevisions - 2) >= 0;
If Revisions - #Revisions - 2 is negative it will throw an
An invalid floating point operation occurred.
error
If the limit is 100,
UPDATE Article
SET Revisions = LEAST(Revisions + 1, 100)
where Id = #p0