How do I need to write my SQL script to ensure my new column is visible on following lines after it is created.
This is the general form of my SQL:
BEGIN TRANSACTION
if (not exists(select 1 from THIS_TABLE))
BEGIN
ALTER TABLE THIS_TABLE add THIS_COLUMN int
END
COMMIT
BEGIN TRANSACTION
IF (NOT EXISTS (SELECT 1 FROM THIS_TABLE
WHERE THIS_COLUMN = 1))
BEGIN
UPDATE THIS_TABLE SET THIS_COLUMN = 1
END
COMMIT
This is the error I'm getting:
Invalid column name 'THIS_COLUMN'.
on this line:
IF (NOT EXISTS (SELECT 1 FROM THIS_TABLE
WHERE THIS_COLUMN = 1))
The column has to be created before a query that uses it can be parsed. You can accomplish this by putting the update in a different batch, using the "go" keyword:
alter table t1 add c1 int
go
update t1 set c1 = 1
Or by running the second transaction as dynamic SQL:
alter table t1 add c1 int
exec ('update t1 set c1 = 1')
What Andomar said is correct, you need to use the go keyword.
However, the big problem is that your logic looks wrong. Let me go through each use case:
If THIS_TABLE is not empty
If the table is not empty, the if below returns false and you will never add the new column.
if (not exists(select 1 from THIS_TABLE))
BEGIN
ALTER TABLE THIS_TABLE add THIS_COLUMN int
END
Then, the next script obviously fails, because there is no such column THIS_COLUMN:
IF (NOT EXISTS (SELECT 1 FROM THIS_TABLE
WHERE THIS_COLUMN = 1))
If THIS_TABLE is empty
If the table is empty, the column is added:
if (not exists(select 1 from THIS_TABLE))
BEGIN
ALTER TABLE THIS_TABLE add THIS_COLUMN int
END
But then the next if will always be true and the update statement will affect zero rows (because table is empty).
IF (NOT EXISTS (SELECT 1 FROM THIS_TABLE
WHERE THIS_COLUMN = 1))
BEGIN
UPDATE THIS_TABLE SET THIS_COLUMN = 1
END
Related
I have two tables in the database, they have a one-to-many relationship (Example: The table dbo.Tree [tree_id, tree_code] has many dbo.Fruits[id, name, father_tree_id, father_tree_code]) .
I'm trying to create a trigger for when the column codigo_arvore_pai of dbo.Frutos is updated or inserted into it, the column father_tree_code of dbo.Frutos is updated with the value corresponding to the tree_id of the dbo.Tree table. The condition for this is code_tree of dbo.Tree to be equal code_tree_father of dbo.Fruits.
CREATE TRIGGER [dbo].[tr_updateFruit] on [dbo].[Fruits]
AFTER INSERT, UPDATE
AS
IF (UPDATE(father_tree_code))
BEGIN
UPDATE dbo.Fruits
SET id_arvore_pai = A.id_arvore
FROM dbo.Fruits as obj
INNER JOIN dbo.Tree A ON obj.father_tree_code = A.tree_code
WHERE obj.Id IN (SELECT DISTINCT obj.Id FROM dbo.Fruits)
END;
What's wrong?
When the command to update the SQL server is executed, in fact, first the record is deleted and then the new record is inserted again with new changes, giving the illusion to the user that the editing has been done on the desired fields. But in fact, the update command is a two-step command that consists of a deletion and an insertion. First, you must specify the type of action or command executed. You can use the following code inside of the trigger for this reason:
DECLARE #WhatActionHappened as char(1);
SET #WhatActionHappened = (CASE WHEN EXISTS(SELECT * FROM INSERTED)
AND EXISTS(SELECT * FROM DELETED)
THEN 'U' -- Set to Updated.
WHEN EXISTS(SELECT * FROM INSERTED)
THEN 'I' -- Set to Insert.
WHEN EXISTS(SELECT * FROM DELETED)
THEN 'D' -- Set to Deleted.
ELSE NULL -- Skip. It may have been a "failed delete".
END)
After that, you can use the trigger as follows to insert and edit.
CREATE TRIGGER [dbo].[tr_updateFruit] on [dbo].[Fruits]
AFTER INSERT, UPDATE
AS
BEGIN
DECLARE #WhatActionHappened as char(1);
SET #WhatActionHappened = (CASE WHEN EXISTS(SELECT * FROM INSERTED)
AND EXISTS(SELECT * FROM DELETED)
THEN 'U' -- Set to Updated.
WHEN EXISTS(SELECT * FROM INSERTED)
THEN 'I' -- Set to Insert.
--WHEN EXISTS(SELECT * FROM DELETED)
--THEN 'D' -- Set to Deleted.
ELSE NULL -- Skip. It may have been a "failed delete".
END)
IF(#WhatActionHappened = 'U' OR #WhatActionHappened = 'I')
BEGIN
UPDATE dbo.Fruits
SET id_arvore_pai = A.id_arvore
FROM dbo.Fruits as obj
INNER JOIN dbo.Tree A ON obj.father_tree_code = A.tree_code
WHERE obj.Id IN (SELECT DISTINCT i.Id FROM Inserted i)
END
END
looking a bit of direction or guidance as to why I’m getting multiple rows using my trigger. Basically I have a web app that controls Asset Types (i.e Laptops, Phones etc), what I’m trying to do with this trigger is when the Asset Type Name (at_typedesc) changes that I log to an audit table (in this case sql_log) what the old name was and what the new name is.
This is working, but for some reason I get multiple lines written at the INSERT TO SQL_LOG statement. It does write the old name & new name, but then I’ll get 3 additional rows which has the old name showing the new name...
This is currently on a 2008 SQL Server.
-- create the trigger
go
create trigger trg_InsteadOfUpdate on [dbo].[lkp_asset_types]
instead of update
as
begin
DECLARE #triggerAction varchar(1)
-- determine the TRIGGER action
-- this allows us to tell if its an INSERT or an UPDATE
SELECT #triggerAction = CASE
WHEN EXISTS(SELECT 1 FROM INSERTED)
AND EXISTS(SELECT 1 FROM deleted) THEN 'U'
WHEN EXISTS(SELECT 1 FROM inserted) THEN 'I'
ELSE 'D' END;
-- get the orginally asset name from the DELETED table
-- this contains the rows as they were BEFORE the UPDATE Statement
DECLARE #orgAssetTypeName varchar(255)
SET #orgAssetTypeName = (SELECT top 1 at_typedesc from lkp_asset_types WHERE at_id = (select at_id from deleted))
-- UPDATE to the new asset name based on the NEW value in the INSERTED Table
update lkp_asset_types
set at_typedesc = (select at_typedesc from inserted)
where at_id = (select at_id from inserted)
-- get the new asset name from the INSERTED table
-- this contains the rows as they were AFTER the UPDATE Statement
DECLARE #newAssetTypeName varchar(255)
SET #newAssetTypeName = (SELECT top 1 at_typedesc from lkp_asset_types WHERE at_id = (select at_id from inserted))
insert into sql_log
(sql_log)
values ('SQL PRE Changed from : ' + #orgAssetTypeName + ' to: ' + #newAssetTypeName + '. Action = ' + #triggerAction)
end
go
Logic like this in a trigger in SQL Server is just broken:
where at_id = (select at_id from inserted)
I really wish the SQL Server parser issued a warning when encountering such constructs.
There is no guarantee that inserted has only one value (nor deleted).
That is how SQL Server defines triggers: as set operations. If multiple rows are inserted at the same, then the inserted and deleted "tables" have multiple rows.
That part is simple. You will need to rewrite the trigger to take this into account.
On checking my web code the update button was performing additional updates, this caused the trigger to fire more than once thus causing duplicate rows.
create table dbo.lkp_asset_types_test
(
at_id int identity,
at_typedesc varchar(100)
)
go
create trigger trg_InsteadOfUpdate_test on [dbo].[lkp_asset_types_test]
instead of update
as
begin
select 'trigger fired!!!!'
if not exists(select * from inserted)
and not exists(select * from deleted)
begin
return;
end
--update (maybe only the diffs?)
update t
set at_typedesc = i.at_typedesc
from dbo.lkp_asset_types_test as t
join inserted as i on t.at_id = i.at_id;
--where t.at_typedesc <> i.at_typedesc & nulls??
--insert into sql_log(sql_log)
select
'SQL PRE Changed from : ' + isnull(d.at_typedesc, '*null*') + ' to: ' + isnull(i.at_typedesc, '*null*') + '. Action = U'
from inserted as i
join deleted as d on i.at_id = d.at_id
--where i.at_typedesc <> d.at_typedesc & nulls ??
end
go
insert into dbo.lkp_asset_types_test(at_typedesc) values ('A'), ('B'), ('C'), ('D'), (NULL);
go
update dbo.lkp_asset_types_test
set at_typedesc = case when at_id%2=0 then isnull(at_typedesc, 'X') else isnull(at_typedesc, '') + 'xyz' end
go
select *
from dbo.lkp_asset_types_test;
go
update dbo.lkp_asset_types_test
set at_typedesc = case when at_id%2=0 then at_typedesc else at_typedesc + 'xyz' end
where 1=2
go
--
drop table lkp_asset_types_test;
I have simple script:
IF NOT EXISTS (SELECT 1 FROM INFORMATION_SCHEMA.Columns
WHERE table_name = 'T1' AND column_name = 'C1')
BEGIN
ALTER Table T1
ADD C1 BIT NOT NULL CONSTRAINT DF_T1_C1 DEFAULT 0
UPDATE Table T1
SET C1 = 1
END
GO
I am getting error
Incorrect syntax near the keyword 'Table'.
I tried this solution but it didn't update column value. I came accross this but I think this is not my case as I don't want to catch exceptions or do any transaction. Do I have easy option to do this?
Putting GO seperator didn't help too.
As Joe Taras pointed out, I have changed my script but now getting error
Invalid column name 'C1'.
You need to ensure that that UPDATE isn't compiled until after you're actually created the column.
Put it in a separate context by using EXEC:
IF NOT EXISTS (SELECT 1 FROM INFORMATION_SCHEMA.Columns
WHERE table_name = 'T1' AND column_name = 'C1')
BEGIN
ALTER Table T1
ADD C1 BIT NOT NULL CONSTRAINT DF_T1_C1 DEFAULT 0
EXEC('UPDATE Table T1
SET C1 = 1')
END
GO
Your row:
UPDATE Table T1 SET C1 = 1
has wrong because you have specified table keyword.
The correct syntax is:
UPDATE T1 SET C1 = 1
EDIT 1
Rewrite your script as follow, so after GO separator you'll update your field, so you are sure the DDL has taken by DBMS:
IF NOT EXISTS (SELECT 1 FROM INFORMATION_SCHEMA.Columns
where table_name = 'T1' AND column_name = 'C1')
BEGIN
ALTER Table T1
ADD C1 BIT NOT NULL CONSTRAINT DF_T1_C1 DEFAULT 0
END
GO
UPDATE T1 SET C1 = 1
EDIT 2
IF NOT EXISTS (SELECT 1 FROM INFORMATION_SCHEMA.Columns
where table_name = 'T1' AND column_name = 'C1')
BEGIN
ALTER Table T1
ADD C1 BIT NOT NULL CONSTRAINT DF_T1_C1 DEFAULT 0
EXEC('UPDATE T1 SET C1 = 1')
END
GO
if there is no entry in the table update cannot be done
try it after giving asingle entry it works
We are using the following trigger in SQL Server to maintain the history now I need to identify the operations just like insert,update or delete. I found some information HERE but it doesn't works with the SQL Server.
CREATE TRIGGER audit_guest_details ON [PMS].[GSDTLTBL]
FOR INSERT,UPDATE,DELETE
AS
DECLARE #SRLNUB1 INT;
DECLARE #UPDFLG1 DECIMAL(3,0);
SELECT #SRLNUB1 = I.SRLNUB FROM inserted I;
SELECT #UPDFLG1 = I.UPDFLG FROM inserted I;
BEGIN
/* Here I need to identify the operation and insert the operation type in the GUEST_ADT 3rd field */
insert into dbo.GUEST_ADT values(#SRLNUB1,#UPDFLG1,?);
PRINT 'BEFORE INSERT trigger fired.'
END;
GO
But here I need to identify the operation and want to insert operation type accordingly.
Here I don't want to create three trigger for every operations
For Inserted : Rows are in inserted only.
For Updated: Rows are in inserted and deleted.
For Deleted: Rows are in deleted only.
DECLARE #event_type varchar(42)
IF EXISTS(SELECT * FROM inserted)
IF EXISTS(SELECT * FROM deleted)
SELECT #event_type = 'update'
ELSE
SELECT #event_type = 'insert'
ELSE
IF EXISTS(SELECT * FROM deleted)
SELECT #event_type = 'delete'
ELSE
--no rows affected - cannot determine event
SELECT #event_type = 'unknown'
This is a simplified version of Mikhail's answer that uses a searched CASE expression.
DECLARE #Operation varchar(7) =
CASE WHEN EXISTS(SELECT * FROM inserted) AND EXISTS(SELECT * FROM deleted)
THEN 'Update'
WHEN EXISTS(SELECT * FROM inserted)
THEN 'Insert'
WHEN EXISTS(SELECT * FROM deleted)
THEN 'Delete'
ELSE
NULL --Unknown
END;
Since you can get multiple rows at once we do it as follows.
INSERT INTO Log_Table
(
LogDate
,LogAction
-- your field list here
,Field0
-- Example : Tracking new and old value for a specific field
-- Make sure that the [Field1_Old] is nullable or has a default value
,Field1,Field1_Old
)
SELECT
LogDate=GETDATE()
,LogAction = CASE WHEN d.[PK_Field] IS NULL THEN 'I' ELSE 'U' END
,i.Field0
,i.Field1, d.Field1
FROM inserted i
LEFT JOIN deleted d on i.[PK_Field]=d.[PK_Field]
WHERE i.[PK_Field] IS NOT NULL
INSERT INTO Log_Table
(
LogDate
,LogAction
-- your field list here
,Field0
-- Example : Tracking new and old value for a specific field
-- Make sure that the [Field1_Old] is nullable or has a default value
,Field1,Field1_Old
)
SELECT
LogDate=GETDATE()
,LogAction = 'D'
,d.Field0
,d.Field1, NULL
FROM deleted d
LEFT JOIN inserted i on i.[PK_Field]=d.[PK_Field]
WHERE i.[PK_Field] IS NULL
create trigger my_trigger on my_table
after update , delete , insert
as
declare #inserting bit
declare #deleting bit
declare #updating bit = 0
select #inserting = coalesce (max(1),0) where exists (select 1 from inserted)
select #deleting = coalesce (max(1),0) where exists (select 1 from deleted )
select #inserting = 0
, #deleting = 0
, #updating = 1
where #inserting = 1 and #deleting = 1
print 'Inserting = ' + ltrim (#inserting)
+ ', Deleting = ' + ltrim (#deleting)
+ ', Updating = ' + ltrim (#updating)
If all three are zero, there are no rows affected and I think there is no way to tell whether it is an update/delete/insert.
I'm writing a stored procedure to update multiple records based on a table variable parameter.
The existing table is: Tb_Project_Image with relevant columns:
id PK (identity 1,1)
cat_ord decimal(4,2)
The procedure will receive a temporary table variable (shown in the code below) containing the id as PI_ID, and the new value for cat_ord as newCatOrd. idx is a simple identity for each row containing 1...n where n is the rowcount of #tempTable.
For each row in #tempTable, I want to update Tb_Project_Image where id = PI_ID to the corresponding value.
DECLARE #tempTable table (
idx smallint Primary Key IDENTITY(1,1),
PI_ID bigint,
newCatOrd decimal(4, 2) not null )
INSERT INTO #tempTable values (3, 7.01)
INSERT INTO #tempTable values (4, 7.02)
INSERT INTO #tempTable values (5, 7.03)
--etc...
DECLARE #error int
DECLARE #update int
DECLARE #iter int
SET #iter = 1
BEGIN TRAN
WHILE #iter <= (select COUNT(*) from #tempTable)
BEGIN
UPDATE Tb_Project_Image
SET cat_ord = (SELECT newCatOrd FROM #tempTable
WHERE idx = #iter)
WHERE id = (SELECT PI_ID FROM #tempTable
WHERE idx = #iter)
--error checking
set #error = ##ERROR
set #update = ##ROWCOUNT
IF ((#error = 0) AND (#update = 1))
BEGIN
SET #iter = #iter + 1
CONTINUE
END
ELSE
BREAK
END
IF ((#error = 0) AND (#update = 1))
COMMIT TRAN
ELSE
ROLLBACK TRAN
GO
Now, the error checking is because, to ensure integrity, EACH row in the temporary table MUST make 1 update. (explanation omitted to save space) If a single iteration of the while loop threw an error, or didn't effect exactly 1 row, I want to break the loop and rollback the transaction
THE PROBLEM I'm having is that this error checking is not working. I'm currently running it with 14 rows in #tempTable and the 11th uses a PI_ID not found in the Project_Image table. Therefore, #update = 0... but it continues the loop and commits the data.
I'd be doubly glad if someone had a method of doing this that only used a single update statement.
You cannot do it this way, because even SET resets the state of ##ERROR and ##ROWNUMBER variables. In this case ##ROWCOUNT is set to 1 after set #error = ##ERROR. If you do not assign the values to local variables, your code will work:
IF ((##error = 0) AND (##rowcount = 1))
But you might rather try try...catch error handling and test ##rowcount separately after update.
UPDATE: doing it in single update:
UPDATE t
SET cat_ord = tt.newCatOrd
FROM Tb_Project_Image t
INNER JOIN #tempTable tt
ON t.id = tt.PI_ID
-- If there was PI_ID not found in Tb_Project_Image
-- But I think that this should have been dealt with
-- During the initial loading of temporary table
IF ##ROWCOUNT <> (select count (*) from #tempTable)
BEGIN
-- Error reporting here
ROLLBACK TRANSACTION
END
Instead of updating and then rolling back, you could also use a CTE to determine if any records should be updated prior to performing the update. Something like this should work:
WITH NON_SINGLETON AS (
-- Find any records in #tempTable that don't match
-- exactly one record in Tb_Project_Image
SELECT t.PI_ID, COUNT(pi.id) C
FROM #tempTable t
LEFT JOIN Tb_Project_Image pi ON t.PI_ID = pi.id
GROUP BY t.PI_ID
HAVING COUNT(pi.id) != 1
)
UPDATE Tb_Project_Image
SET cat_ord = t.newCatOrd
FROM Tb_Project_Image pi
JOIN #tempTable t ON pi.id = t.PI_ID
-- If any invalid records were found in the CTE,
-- then this condition will fail for all rows
-- and nothing will be updated
WHERE NOT EXISTS(SELECT 1 FROM NON_SINGLETON)
If it's possible for #tempTable to have duplicate entries for the same PI_ID, then this will handle those scenarios as well. And since it's a single statement, you don't have to explicitly managing the transaction in the proc (if it's the only thing that needs to be included in the transaction).