In Postgres, I can write
INSERT .. RETURNING *
To retrieve all values that had been generated during the insert. In Oracle, HSQLDB, I can use
String[] columnNames = ...
PreparedStatement stmt = connection.prepareStatement(sql, columnNames);
// ...
stmt.execute();
stmt.getGeneratedKeys();
To retrieve all values that had been generated. MySQL is a bit limited and only returns columns that are set to AUTO_INCREMENT. But how can this be done with Sybase SQL Anywhere? The JDBC driver does not implement these methods, and there is no INSERT .. RETURNING clause, as in Postgres. Is there way to do it, other than maybe running
SELECT ##identity
immediately after the insert?
My current implementation executes three consecutive SQL statements:
-- insert the data first
INSERT INTO .. VALUES (..)
-- get the generated identity value immediately afterwards
SELECT ##identity
-- get the remaining values from the record (possibly generated by a trigger)
SELECT * FROM .. WHERE ID = :previous_identity
The third statement can be omitted, if only the ID column is requested
Related
I am new to Oracle. I have a table in Oracle which has 4 columns Period, Open_Flag,Creation_Dt,Updated_By.
The Period column is the Primary key of the table. I have created a proc which will check the value of period from input parameter in the table, if its existing, the value of Open_flag has to be updated else a new record shall be inserted.
create or replace
PROCEDURE PROC_REF_SAP_PERIOD(
V_PERIOD IN NUMBER,V_OPEN_FLAG IN VARCHAR2,V_CREATION_DT IN DATE,V_UPDATED_BY IN VARCHAR2)
AS
BEGIN
MERGE INTO REF_SAP_PERIOD T
USING (SELECT * FROM REF_SAP_PERIOD WHERE PERIOD=V_PERIOD )S
ON (T.PERIOD=S.PERIOD )
WHEN MATCHED THEN UPDATE SET OPEN_FLAG = V_OPEN_FLAG --WHERE PERIOD=V_PERIOD AND CREATION_DT=V_CREATION_DT AND UPDATED_BY=V_UPDATED_BY
WHEN NOT MATCHED THEN INSERT (PERIOD,OPEN_FLAG,CREATION_DT,UPDATED_BY) VALUES (V_PERIOD,V_OPEN_FLAG,V_CREATION_DT,V_UPDATED_BY);
END;
The issue is that the Update is working well in this case, however, the insert is not working. Please help.
You are merging table with itself, filtered by period. Obviously, it will never see your non-existent values in itself.
Try this line instead of your USING line:
using (select V_PERIOD "period" from dual)S
I want update all values in my tables, but this can kill my database
UPDATE Table_1
SET Value = 'Some string with but changed'
where value = 'Some string without changes';
Can I do this by procedures, and it guarantee that it will not perform in infinty please i need some tips?
Edit
I read about cursors, but how can i use it
Your SQL seems fine and that is the preferred solution. A cursor will normally be far, far slower.
If you cannot create an index and the update above is really that slow, try the following. Considering I don't have the rest of the table definition to work with, I assume your primary key is a single field named ID:
First, create a temporary table with only the matching records:
CREATE TEMPORARY TABLE temp as
SELECT *
FROM Table_1
WHERE value = 'Some string without changes';
Then, update using this temporary table:
UPDATE Table_1 SET
Table_1.Value = 'Some string with but changed'
WHERE EXISTS (
SELECT *
FROM Temp
WHERE Temp.ID = Table_1.ID
);
Another approach if your DB is higher than 11g R1 version. Oracle has provided a beautiful package called DBMS_PARALLEL_EXECUTE which is used for large DMLS or any process which can be split into chunks and can be parallely done.
I'm trying to store a row in a DB2 database table where the primary key is an autoincrement. This works fine but I'm having trouble wrapping my head around how to retrieve the primary key value for further processing after successfully inserting the row. How do you achieve this? #JdbcInsert only returns the amount of rows that were inserted ...
Since there does not seem to be a way to do this with SSJS (at least to me), I moved this particular piece of logic from my SSJS controller to a Java helper bean I created for JDBC related tasks. A Statement is capable of handing back generated keys (using the method executeUpdate()). So I still create my connection via #JdbcGetConnection, but then hand it in into the bean. This is the interesting part of the bean:
/**
* SQL contains the INSERT Statement
*/
public int executeUpdate(Connection conn, String SQL){
int returnVal;
Statement stmt = conn.createStatement();
stmt.executeUpdate(SQL,
Statement.RETURN_GENERATED_KEYS);
if(!conn.getAutoCommit()) conn.commit();
ResultSet keys = stmt.getGeneratedKeys();
if(keys.next()){
returnVal = keys.getInt(1);
} else {
returnVal = -1;
}
return returnVal;
}
If you insert more than one row at a time, you'll need to change the key retrieval handling, of course.
In newer DB2 Versions you can transform every Insert into a Select to get automatic generated key columns. An example is:
select keycol from Final Table (insert into table (col1, col2) values (?,?))
keycol is the name of your identity column
The Select can be executed with the same #Function than your usual queries.
I am familiar with Sybase which allows queries with format: IF EXISTS () THEN ... ELSE ... END IF (or very close). This a powerful statement that allows: "if exists, then update, else insert".
I am writing queries for DB2 on IBM iSeries box. I have seen the CASE keyword, but I cannot make it work. I always receive the error: "Keyword CASE not expected."
Sample:
IF EXISTS ( SELECT * FROM MYTABLE WHERE KEY = xxx )
THEN UPDATE MYTABLE SET VALUE = zzz WHERE KEY = xxx
ELSE INSERT INTO MYTABLE (KEY, VALUE) VALUES (xxx, zzz)
END IF
Is there a way to do this against DB2 on IBM iSeries? Currently, I run two queries. First a select, then my Java code decides to update/insert. I would rather write a single query as my server is located far away (across the Pacific).
+UPDATE+
DB2 for i, as of version 7.1, now has a MERGE statement which does what you are looking for.
>>-MERGE INTO--+-table-name-+--+--------------------+----------->
'-view-name--' '-correlation-clause-'
>--USING--table-reference--ON--search-condition----------------->
.------------------------------------------------------------------------.
V |
>----WHEN--+-----+--MATCHED--+----------------+--THEN--+-update-operation-+-+----->
'-NOT-' '-AND--condition-' +-delete-operation-+
+-insert-operation-+
'-signal-statement-'
See IBM i 7.1 InfoCenter DB2 MERGE statement reference page
DB/2 on the AS/400 does not have a conditional INSERT / UPDATE statement.
You could drop the SELECT statement by executing an INSERT directly and if it fails execute the UPDATE statement. Flip the order of the statements if your data is more likely to UPDATE than INSERT.
A faster option would be to create a temporary table in QTEMP, INSERT all of the records into the temporary table and then execute a bulk UPDATE ... WHERE EXISTS and INSERT ... WHERE NOT EXISTS at the end to merge all of the records into the final table. The advantage of this method is that you can wrap all of the statements in a batch to minimize round trip communication.
You can perform control-flow logic (IF...THEN...ELSE) in an SQL stored procedure. Here's sample SQL source code:
-- Warning! Untested code ahead.
CREATE PROCEDURE libname.UPSERT_MYTABLE (
IN THEKEY DECIMAL(9,0),
IN NEWVALUE CHAR(10) )
LANGUAGE SQL
MODIFIES SQL DATA
BEGIN
DECLARE FOUND CHAR(1);
-- Set FOUND to 'Y' if the key is found, 'N' if not.
-- (Perhaps there's a more direct way to do it.)
SET FOUND = 'N';
SELECT 'Y' INTO FOUND
FROM SYSIBM.SYSDUMMY1
WHERE EXISTS
(SELECT * FROM MYTABLE WHERE KEY = THEKEY);
IF FOUND = 'Y' THEN
UPDATE MYTABLE
SET VALUE = NEWVALUE
WHERE KEY = THEKEY;
ELSE
INSERT INTO MYTABLE
(KEY, VALUE)
VALUES
(THEKEY, NEWVALUE);
END IF;
END;
Once you create the stored procedure, you call it like you would any other stored procedure on this platform:
CALL UPSERT_MYTABLE( xxx, zzz );
This slightly over complex piece of SQL procedure will solve your problem:
IBM Technote
If you want to do a mass update from another table then have a look at the MERGE statement which is an incredibly powerful statement which lets you insert, update or delete depending on the values from another table.
IBM DB2 Syntax
In Oracle, given a simple data table:
create table data (
id VARCHAR2(255),
key VARCHAR2(255),
value VARCHAR2(511));
suppose I want to "insert or update" a value. I have something like:
merge into data using dual on
(id='someid' and key='testKey')
when matched then
update set value = 'someValue'
when not matched then
insert (id, key, value) values ('someid', 'testKey', 'someValue');
Is there a better way than this? This command seems to have the following drawbacks:
Every literal needs to be typed twice (or added twice via parameter setting)
The "using dual" syntax seems hacky
If this is the best way, is there any way around having to set each parameter twice in JDBC?
I don't consider using dual to be a hack. To get rid of binding/typing twice, I would do something like:
merge into data
using (
select
'someid' id,
'testKey' key,
'someValue' value
from
dual
) val on (
data.id=val.id
and data.key=val.key
)
when matched then
update set data.value = val.value
when not matched then
insert (id, key, value) values (val.id, val.key, val.value);
I would hide the MERGE inside a PL/SQL API and then call that via JDBC:
data_pkg.merge_data ('someid', 'testKey', 'someValue');
As an alternative to MERGE, the API could do:
begin
insert into data (...) values (...);
exception
when dup_val_on_index then
update data
set ...
where ...;
end;
I prefer to try the update before the insert to save having to check for an exception.
update data set ...=... where ...=...;
if sql%notfound then
insert into data (...) values (...);
end if;
Even now we have the merge statement, I still tend to do single-row updates this way - just seems more a more natural syntax. Of course, merge really comes into its own when dealing with larger data sets.