I have written a Merge statement to perform Insert/Update in the snowflake and it was observed that the sequence in the Target table gets increment, While executing the Insert Clause but also While update statement also got satisfied/working . can any one help me how to fix this issue?
create or replace table target_table (id integer , description varchar);
create or replace table source_table2 (id integer , description varchar);
create or replace sequence seq1;
Below is the Merge statement I have used...
merge into target_table using source_table2
on target_table.id = source_table2.id
when matched then
update set target_table.description = 'I am Changing'
when not matched then insert (ID, description) values (seq1.nextval, source_table2.description);
can anyone explain how the sequence were processed at the backend and why there was a skip of numbers seen in the Snow Flake?
Please let me know if you need any additional information.
Assuming you're not saying that the sequence value on the target table is getting a new number on the updated record, then you are seeing expected behavior with the sequence in Snowflake. The documentation here is a good read on this:
https://docs.snowflake.com/en/user-guide/querying-sequences.html
Related
I have a table like this.
create table help(
id number primary key,
number_s integer NOT NULL);
I had to insert value 0 from id 1 and id 915 I solved this one in a simple way doing
update help set number_s=0 where id<=915;
This one was easy.
Now I have to set a numbers ( that change every row) from id 915 to last row.
I was doing
update help set number_s=51 where id=916;
update help set number_s=3 where id=917;
There are more than 1.000 row to be updated how can I do it very fast?
When I had this problem I used to use sequence to auto increment value like id (example
insert into help(id,number_s) values (id_sequence.nextval,16);
insert into help(id,number_s) values (id_sequence.nextval,48);
And so on but on this case it cannot be used because in this case id start from 915 and not 1...) How can I do it very fast? I hope it is clear the problem.
Since you have your ids and numbers in a file with a simple structure, it's a fairly small number, and assuming this is something you're going to do once, honestly what I would do would be to pull the file into Excel, use the text functions to build 1000 insert statements and cut and paste them wherever.
If those assumptions are incorrect, you could (1) use sqlldr to load this file into a temporary table and (2) run an update on your help table based on the rows in that temporary table.
As mentioned in previous answers and according to your comment that there is a file stored in your system, You can use the external table / SQL loader to achieve the result.
I am trying to show you the demo as follows:
-- Create an external table pointing to your file
CREATE TABLE "EXT_SEQUENCES" (
"ID" number ,
"number_s" number
)
ORGANIZATION EXTERNAL ( TYPE ORACLE_LOADER
DEFAULT DIRECTORY "<directory name>" ACCESS PARAMETERS (
RECORDS DELIMITED BY NEWLINE
BADFILE 'bad_file.txt'
LOGFILE 'log_file.txt'
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' MISSING FIELD VALUES ARE NULL
) LOCATION ( '<file name>' )
) REJECT LIMIT UNLIMITED;
-- Now update your help table
MERGE INTO help H
USING EXT_SEQUENCES
ON ( H.ID = E.ID)
WHEN MATCHED THEN
UPDATE SET H.number_s = E.number_s;
Note: You need to change the access parameters of the external table according to your actual data in the file.
Hope you will get proper direction now.
Cheers!!
This is an hypothetical case..
I'm trying to find a good approach to make sure that every value inserted in an specific column col1 of my table mytable has a specific string http:// at the begining of the value.
Example:
I want to insert myprofile into mytable so (after my check condition..) the final value would be http://myprofile
I guess that a good approach could be using a trigger on insert but I didn't find anything concrete yet..
Any ideas?
Thank you.
You can try something like this as a starting point - this is for SQL Server (don't know MySQL well enough to provide that trigger code for you):
-- create the trigger, give it a meaningful name
CREATE TRIGGER PrependHttpPrefix
ON dbo.YourTableName -- it's on a specific table
AFTER INSERT, UPDATE -- it's for a specific operation, or several
AS
BEGIN
-- the newly inserted rows are stored in the "Inserted" pseudo table.
-- It has the exact same structure as your table that this trigger is
-- attached to.
-- SQL Server works in such a way that if the INSERT affected multiple
-- rows, the trigger is called *once* and "Inserted" contains those
-- multiple rows - you need to work with "Inserted" as a multi-row data set
--
-- You need to join the "Inserted" rows to your table (based on the
-- primary key for the table); for those rows newly inserted that
-- **do not** start with "http://" in "YourColumn", you need to set
-- that column value to the fixed text "http:/" plus whatever has been inserted
UPDATE tbl
SET YourColumn = 'http://' + i.YourColumn
FROM dbo.YourTableName tbl
INNER JOIN Inserted i ON tbl.PKColumn = i.PKColumn
WHERE LEFT(i.YourColumn, 7) <> 'http://'
END
I'm inserting bulk records using COPY statement in PostgreSQL. What I realize is, the sequence IDs are not getting updated and when I try to insert a record later, it throws duplicate sequence ID. Should I manually update the sequence number to get the number of records after performing COPY? Isn't there a solution while performing COPY, just increment the sequence variable, that is, the primary key field of the table? Please clarify me on this. Thanks in advance!
For instance, if I insert 200 records, COPY does good and my table shows all the records. When I manually insert a record later, it says duplicate sequence ID error. It very well implies that it didn’t increment the sequence ids during COPYing as work fine during normal INSERTing. Instead of instructing the sequence id to set the max number of records, won’t there be any mechanism to educate the COPY command to increment the sequence IDs during its bulk COPYing option?
You ask:
Should I manually update the sequence number to get the number of records after performing COPY?
Yes, you should, as documented here:
Update the sequence value after a COPY FROM:
| BEGIN;
| COPY distributors FROM 'input_file';
| SELECT setval('serial', max(id)) FROM distributors;
| END;
You write:
it didn’t increment the sequence ids during COPYing as work fine during normal INSERTing
But that is not so! :) When you perform a normal INSERT, typically you do not specify an explicit value for the SEQUENCE-backed primary key. If you did, you would run in to the same problems as you are having now:
postgres=> create table uh_oh (id serial not null primary key, data char(1));
NOTICE: CREATE TABLE will create implicit sequence "uh_oh_id_seq" for serial column "uh_oh.id"
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "uh_oh_pkey" for table "uh_oh"
CREATE TABLE
postgres=> insert into uh_oh (id, data) values (1, 'x');
INSERT 0 1
postgres=> insert into uh_oh (data) values ('a');
ERROR: duplicate key value violates unique constraint "uh_oh_pkey"
DETAIL: Key (id)=(1) already exists.
Your COPY command, of course, is supplying an explicit id value, just like the example INSERT above.
I realize that this is a bit old but maybe someone might still be looking for the answer.
As other said COPY works in a similar way as INSERT, so for inserting into a table that has a sequence, you simply don't mention the sequence field at all and it is taken care of for you. For COPY it works in the same exact way. But doesn't it COPY require ALL fields in the table to be present in the text file? The correct answer is NO, it doesn't, but it is the default behavior.
To COPY and leave the sequence out do the following:
COPY $YOURSCHEMA.$YOURTABLE(col1,col2,col3,col4) FROM '$your_input_file' DELIMITER ',' CSV HEADER;
No need to manually update the schema afterwards, it works as intended and in my testing is just about as fast.
You could copy to a sister table, then insert into mytable select * from sister - that would increment the sequence.
If your loaded data has the id field, don't select it for the insert: insert into mytable (col1, col2, col3) select col1, col2, col3 from sister
I have the following hsqldb table, in which I map UUIDs to auto incremented IDs:
SHORT_ID (BIG INT, PK, auto incremented) | UUID (VARCHAR, unique)
Create command:
CREATE TABLE mytable (SHORT_ID BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY, UUID VARCHAR(36) UNIQUE)
In order to add new pairs concurrently, I want to use the atomic MERGE INTO statement. So my (prepared) statement looks like this:
MERGE INTO mytable USING (VALUES(CAST(? AS VARCHAR(36)))) AS v(x) ON mytable.UUID = v.x WHEN NOT MATCHED THEN INSERT VALUES v.x
When I execute the statement (setting the placeholder correctly), I always get a
Caused by: org.hsqldb.HsqlException: row column count mismatch
Could you please give me a hint, what is going wrong here?
Thanks in advance.
Epilogue
I reported this behavior as a bug, and it is today (2010-05-25) fixed in the hsqldb SVN repository, per hsqldb-Bugs-2989597. (Thanks, hsqldb!)
Updated Answer
Neat one! Here's what I got to work under HSQLDB 2.0.0rc9, which supports the syntax and the error message you posted:
MERGE INTO mytable
USING (SELECT 'a uuid' FROM dual) AS v(x) -- my own "DUAL" table
ON (mytable.UUID = v.x)
WHEN NOT MATCHED THEN INSERT
VALUES (NULL, x) -- explicit NULL for "SHORT_ID" :(
Note, I could not convince 2.0.0rc9 to accept ... THEN INSERT (UUID) VALUES (x), which is IIUC a perfectly acceptable and clearer specification than the above. (My SQL knowledge is hardly compendious, but this looks like a bug to me.)
Original Answer
You appear to be INSERTing a single value (a 1-tuple) into a table with more than one column. Perhaps you can modify the end of your statement to read:
... WHEN NOT MATCHED INSERT ("UUID") VALUES (v.x)
I got same problems but solve in few minutes.
Its occur when datavalues and table structure are not same.Add explicit (NULL) in your empty column value.
Like i created table
TestCase table:
ID TESTCASEID DESCRIPTION
but your insertion statement you donot want to add any description for any testcase description then you have to explicite in insertion statement you have to set null value for description
I have a postgres table like this:
CREATE SEQUENCE seq;
CREATE TABLE tbl (id INTEGER DEFAULT VALUE nextval('seq'), data VARCHAR);
When I insert into the table:
INSERT INTO tbl (data) VALUES ('something');
How can I get back the value of the id field for the record I just created?
(Note, I may have got some of the SQL syntax a bit off; the gist should be clear, though)
Suppose for the sake of argument that I'm not able to call currval on the same session because I don't control the transaction boundaries. I might be working in the same session with my next call, but I might not be, too.
You're looking for INSERT ... RETURNING. From The Manual's section on INSERT:
The optional RETURNING clause causes INSERT to compute and return value(s) based on each row actually inserted. This is primarily useful for obtaining values that were supplied by defaults, such as a serial sequence number. However, any expression using the table's columns is allowed. The syntax of the RETURNING list is identical to that of the output list of SELECT.
In the same session:
SELECT currval('seq');
EDIT: But if you can't use currval/nextval because you don't know if the inserting and selecting of the sequence value will occur in the same session, and if you're on postgresql 8.2 or later, you could probably write your insert statement like this.
INSERT INTO tbl (data) VALUES ('something') RETURNING id;
which should also return the last inserted id.
Use nextval and currval, take a look here: http://www.postgresql.org/docs/8.0/static/functions-sequence.html