I am using Sybase ASE 15.7. I wish to create trigger before insert such that before inserting, I want to modify some fields in the inserted row.
Please help Thanks!
From a trigger perspective you have a couple options:
for insert trigger; must be defined against the base table; this trigger will fire after the data has been inserted to the table; the trigger would be coded to perform updates against the base table of the newly inserted row
instead of trigger; must be defined against a view (the view would be defined against the base table); you would perform your insert against the view which would cause the instead of trigger to fire; the trigger would be coded to copy/manipulate the data from the inserted pseudo-table and write the final data set into the base table
See create trigger for more details.
Another option would be to write a stored procedure that does all of the pre-insert changes; instead of inserting directly to the base table you would call the stored proc (passing in all of the column values as input parameters). [granted, less than ideal]
'course one other option would be to have the application perform the pre-insert checks and edits before inserting the final data set to the base table.
PROBLEM SUMMARY
I have to write I/U/D-statement-generating-triggers for a bucardo/symmetricDS-inspired homemade bidirectional replication system between Sybase ADS and Postgresql 11 groups of nodes, using BEFORE triggers on any Postgresql and Sybase DB that creates Insert/Update/Delete commands based on the command entered in a replicating source table: e.g. an INSERT INTO PERSON (first_name,last_name,gender,age,ethnicity) Values ('John','Doe','M',42,'C') and manipulate them into a corresponding Insert statement, and UPDATE by getting OLD and NEW values to dynamically make an UPDATE statement, along with getting OLD values to make a DELETE command, all to run per command on a destination at some interval.
I know this is difficult and no one does this but it is for a job and I have no other options and can't object to offer a different solution. I have no other teammates or human resources to help outside of SO and something like Codementors, which was not so helpful. My idea/strategy is to copy parts of bucardo/SymmetricDS when inserting OLD and NEW values for generating a statement/command to run on the destination. Right now, I am snapshotting the whole table to a CSV as opposed to doing by individual command, but by command and looping through table that generates and saves commands will make the job much easier.
One big issue is that they come from Sybase ADS and have a mixed Key/Index structure (many tables have NO PK) and are mirroring that in Postgresql, so I am trying to write PK-less statements, or all-column commands to get around the no-pk tables. They also will only replicate certain columns for certain tables, so I have a column in a table for them to insert the column names delimited by ';' and then split it out into an array and link the column names to the values for each statement to generate a full command for I/U/D, Hopefully. I am open to other strategies but this is a big solo project and I have gone at it many ways with much difficulty.
I mostly come from DBA background and have some programming experience with the fundamentals, so I am mostly pseudocoding each major sequence,googling for syntax by part, and adjusting as I go or encounter a language incapability. I am thankful for any help given, as I am getting a bit desperate and discouraged.
WHAT I HAVE TRIED
I have to do this for Sybase ADS and Postgresql but this question is intially over ADS since it's more challenging and older.
To have one "Log" table which tracks row changes for each of the replicating tables and records and ultimately dynamically generates a command is the goal for both platforms. I am trying to make trigger statements like:
CREATE TRIGGER PERSON_INSERT
ON PERSON
BEFORE
INSERT
BEGIN
INSERT INTO Backlog (SourceTableID, TriggerType, Status, CreateTimeDate, NewValues) select ID, 'INSERT','READY', NOW(),''first_name';'last_name';'gender';'age';'ethnicity'' from __new;
END;
CREATE TRIGGER PERSON_UPDATE
ON PERSON
BEFORE
UPDATE
BEGIN
INSERT INTO Backlog (SourceTableID, TriggerType, Status, CreateTimeDate, NewValues) select ID, 'U','UPDATE','READY', NOW(),''first_name';'last_name';'gender';'age';'ethnicity'' from __new;
UPDATE Backlog SET OldValues=select ''first_name';'last_name';'gender';'age';'ethnicity'' from __old where SourceTableID=select ID from __old;
END;
CREATE TRIGGER PERSON_DELETE
ON PERSON
BEFORE
DELETE
BEGIN
INSERT INTO Backlog (SourceTableID, TriggerType, Status, CreateTimeDate, OldValues) select ID, 'D','DELETE','READY', NOW(),''first_name';'last_name';'gender';'age';'ethnicity'' from __old;
END;
but I would like the "''first_name';'last_name';'gender';'age';'ethnicity''" to come from another table as a value to make it dynamic since multiple tables will write their value and statement info to the single log table. Then, it can be made into a variable and then probably split to link to the corresponding values so the IUD statements can be made which will be executed on the destination one at a time.
ATTEMPTED INCOMPLETE SAMPLE TRIGGER CODE
CREATE TRIGGER PERSON_INSERT
ON PERSON
BEFORE
INSERT
BEGIN
--Declare #Columns string
--#Columns=select Columns from metatable where tablename='PERSON'
--String Split(#Columns,';') into array to correspond to new and old VALUES
--#NewValues=#['#Columns='+NEW.#Columns+'']
INSERT INTO Backlog (SourceTableID, TriggerType, Status, CreateTimeDate, NewValues) select ID, 'INSERT','READY', NOW(),''first_name';'last_name';'gender';'age';'ethnicity'' from __new;
END;
CREATE TRIGGER PERSON_UPDATE
ON PERSON
BEFORE
UPDATE
BEGIN
--Declare #Columns string
--#Columns=select Columns from metatable where tablename='PERSON'
--String Split(#Columns,';') into array to correspond to new and old VALUES
--#NewValues=#['#Columns='+NEW.#Columns+'']
--#OldValues=#['#Columns='+OLD.#Columns+'']
INSERT INTO Backlog (SourceTableID, TriggerType, Status, CreateTimeDate, NewValues) select ID, 'U','UPDATE','READY', NOW(),''first_name';'last_name';'gender';'age';'ethnicity'' from __new;
UPDATE Backlog SET OldValues=select ''first_name';'last_name';'gender';'age';'ethnicity'' from __old where SourceTableID=select ID from __old;
END;
CREATE TRIGGER PERSON_DELETE
ON PERSON
BEFORE
DELETE
BEGIN
--Declare #Columns string
--#Columns=select Columns from metatable where tablename='PERSON'
--String Split(#Columns,',') into array to correspond to new and old VALUES
--#OldValues=#['#Columns='+OLD.#Columns+'']
INSERT INTO Backlog (SourceTableID, TriggerType, Status, CreateTimeDate, OldValues) select ID, 'D','DELETE','READY', NOW(),''first_name';'last_name';'gender';'age';'ethnicity'' from __old;
END;
CONCLUSION
For each row inserted,updated, or deleted; in a COMMAND column in the log table, I am trying to generate a corresponding 'INSERT INTO PERSON ('+#Columns+') VALUES ('+#NewValues+')' type statement, or an UPDATE or DELETE. Then a Foreach service will run each command value ordered by create time, as the main replication service.
To be clear, I am trying to make my sample code trigger write all old values and new values to a column in a dynamic way without hardcoding the columns in each trigger since it will be used for multiple tables, and writing the values into a single column delimited by a comma or semicolon.
An even bigger wish or goal behind this is to find a way to save/script each IUD command and then be able to run them on subscriber server.DBs of postgresql and Sybase platform, therefore making my own replication from a log
It is a complex but solvable problem that would take time and careful planning to write. I think what you are looking for is the "Execute Immediate" command in ADS SQL syntax. With this command you can create a dynamic statement to then be executed once construction of the SQL statement is terminated. Save each desired column value to a temp table by carefully constructing the statement as a string and then execute it with Execute Immediate. For example:
DECLARE TableColumns Cursor ;
DECLARE FldName Char(100) ;
...
OPEN TableColumns AS SELECT *
FROM system.columns
WHERE parent = #cTableName
AND field_type < 21 //ADS_ROWVERSION
AND field_type <> 6 //ADS_BINARY
AND field_type <> 7; //ADS_IMAGE
While Fetch TableColumns DO
FldName = Trim( TableColumns.Name) ;
StrSql = 'SELECT New.[' + Trim( FldName ) + '] newVal' +
'INTO #myTmpTable FROM ___New n' ;
After constructing the statement as a string it can then be executed like this:
EXECUTE IMMEDIATE STRSQL ;
You can pickup old and new values from __old and __new temp tables that are always available to triggers. Insert values into temp table myTmpTable and then use it to update the target. Remember to drop myTmpTable at the end.
Furthermore, I would think you can create a function on the DD that can actually be called from each trigger on the tables you want to keep track of instead of writing a long trigger for each table and cTableName can be a parameter sent to the function. That would make maintenance a little easier.
I have a SQL Server 2012 UPDATE Trigger which occurs when data is updated within a table in the database (Microsoft Project Server Database) :)
I am using the following statement to get the updated element from the table within the Trigger
SELECT #dataId = INSERTED.Id FROM INSERTED;
But the problem is due to the behaviour of the Microsoft Project Server, that it updates ALL Tasks within a Project even if only one task was changed (each Task is one record in database).
I know that i can get the id of the item which should be updated, but i dont know how i could compare the to updated row with the data which is still in the database within the UPDATE Trigger?
To get what rows actually changed, then use this inside the trigger
SELECT
*
FROM
INSERTED I
JOIN
DELETED D ON I.KeyCol = D.KeyCol
WHERE
NOT EXISTS (
SELECT I.Col1, I.Col2, I.Col3, I.Col4 ...
INTERSECT
SELECT D.Col1, D.Col2, D.Col3, D.Col4 ...
)
The NOT EXISTS..INTERSECT deals with NULLs etc for you already
I have one table named "Staff" in access and also have this table(same name) in SQL 2008.
Both table have thousands of records. I want to merge records from the access table to sql table without affecting the existing records in sql. Normally, I just export using OCBC driver and that works fine if that table doesn't exist in sql server. Please advise. Thanks.
A simple append query from the local access table to the linked sql server table should work just fine in this case.
So, just drop in the first (from) table into the query builder. Then change the query type to append, and you are prompted for the append table name.
From that point on, just drop in the columns you want (do not drop in the PK column, as they need not be used nor transferred in this case).
You can also type in the sql directly in the query builder. Either way, you will wind up with something like:
INSERT INTO dbo_custsql
( ADMINID, Amount, Notes, Status )
SELECT ADMINID, Amount, Notes, Status
FROM custsql1;
This may help: http://www.red-gate.com/products/sql-development/sql-compare/
Or you could write a simple program to read from each data set and do the comparison, adding, updating, and deleting, etc.
I'm still fairly new to T-SQL and SQL 2005. I need to import a column of integers from a table in database1 to a identical table (only missing the column I need) in database2. Both are sql 2005 databases. I've tried the built in import command in Server Management Studio but it's forcing me to copy the entire table. This causes errors due to constraints and 'read-only' columns (whatever 'read-only' means in sql2005). I just want to grab a single column and copy it to a table.
There must be a simple way of doing this. Something like:
INSERT INTO database1.myTable columnINeed
SELECT columnINeed from database2.myTable
Inserting won't do it since it'll attempt to insert new rows at the end of the table. What it sounds like your trying to do is add a column to the end of existing rows.
I'm not sure if the syntax is exactly right but, if I understood you then this will do what you're after.
Create the column allowing nulls in database2.
Perform an update:
UPDATE database2.dbo.tablename
SET database2.dbo.tablename.colname = database1.dbo.tablename.colname
FROM database2.dbo.tablename INNER JOIN database1.dbo.tablename ON database2.dbo.tablename.keycol = database1.dbo.tablename.keycol
There is a simple way very much like this as long as both databases are on the same server. The fully qualified name is dbname.owner.table - normally the owner is dbo and there is a shortcut for ".dbo." which is "..", so...
INSERT INTO Datbase1..MyTable
(ColumnList)
SELECT FieldsIWant
FROM Database2..MyTable
first create the column if it doesn't exist:
ALTER TABLE database2..targetTable
ADD targetColumn int null -- or whatever column definition is needed
and since you're using Sql Server 2005 you can use the new MERGE statement.
The MERGE statement has the advantage of being able to treat all situations in one statement like missing rows from source (can do inserts), missing rows from destination (can do deletes), matching rows (can do updates), and everything is done atomically in a single transaction. Example:
MERGE database2..targetTable AS t
USING (SELECT sourceColumn FROM sourceDatabase1..sourceTable) as s
ON t.PrimaryKeyCol = s.PrimaryKeyCol -- or whatever the match should be bassed on
WHEN MATCHED THEN
UPDATE SET t.targetColumn = s.sourceColumn
WHEN NOT MATCHED THEN
INSERT (targetColumn, [other columns ...]) VALUES (s.sourceColumn, [other values ..])
The MERGE statement was introduced to solve cases like yours and I recommend using it, it's much more powerful than solutions using multiple sql batch statements that basically accomplish the same thing MERGE does in one statement without the added complexity.
You could also use a cursor. Assuming you want to iterate all the records in the first table and populate the second table with new rows then something like this would be the way to go:
DECLARE #FirstField nvarchar(100)
DECLARE ACursor CURSOR FOR
SELECT FirstField FROM FirstTable
OPEN ACursor
FETCH NEXT FROM ACursor INTO #FirstField
WHILE ##FETCH_STATUS = 0
BEGIN
INSERT INTO SecondTable ( SecondField ) VALUES ( #FirstField )
FETCH NEXT FROM ACursor INTO #FirstField
END
CLOSE ACursor
DEALLOCATE ACursor
MERGE is only available in SQL 2008 NOT SQL 2005
insert into Test2.dbo.MyTable (MyValue) select MyValue from Test1.dbo.MyTable
This is assuming a great deal. First that the destination database is empty. Second that the other columns are nullable. You may need an update instead. To do that you will need to have a common key.