I need to add a new row in existing table using Oracle plsql.which doesn't have unique identity column. For example table contain id_no,name of 40 rows.i need to add 40 more rows in same table. I want to add next continues number of max(id_no). For name I am going to insert it manually.without using auto increment.
Try an insert statement with subquery select max(id_no)+1 from table.
Related
We use regular insert for inserting into EmbeddedRocksDB tables.
Inserting a new value for a key updates the value.
There is no DELETE FROM rocksTable where xxx in Clickhouse.
Inserting NULL also doesn't work, which just sets default values for the value part.
So, how do we delete a row, based on the key?
Delete is not implemented.
You can add column (flag) deleted and update it using insert and select only not deleted rows.
I want to add a new column to a specific location in hive table. when i add new column it goes to the last position.
You need to recreate table. If the table is external and data already contains new column, then issue drop and create table statements. General solution is to:
1. create new_table...;
2. insert overwrite new_table select from old_table;
3. drop old_table;
4. alter new_table rename to old_table;
Also if datafiles already contain new column in some position you can
1. Alter table add column
Change column position using this example:
2. ALTER TABLE test_change CHANGE old_name new_name STRING AFTER other_col CASCADE;
See docs here: Change Column Name/Type/Position/Comment
How frequently are people running SELECT *?? Typically, people list out each column in the select statement. Just add the column to the end, and adjust like SELECT last_col, first_col, second_col ...
Alternatively, create a VIEW that runs a select statement with the column ordering you want.
Rename the table to something else, and name the view to the table, and no one would know any different
I have an existing table with millions of records. Now I want to add a new column with default value. But for performances reasons I don't want to apply the new value immediately to existing records. Is there one handy way to do it?
So far, what in my mind is to work around this issue is to:
Add the new column, but do not specify a default (DDL)
Update by chunk the old rows to the default value (to avoid locking the table) (DML)
COMMIT
Alter the column to add a default (DDL)
Another option would be
Add the new column without any default value but make it accept
NULL
While inserting new record, insert NULL for this column
CREATE a AFTER INSERT trigger and update the column with it's
default value.
Something like
CREATE TRIGGER trg_update
AFTER INSERT
ON table_name
BEGIN
UPDATE table_name
SET new_column = (default_value)
WHERE Id_Column = :new.Id_Column;
END;
I have a insert statement on table "test". PK on column x in the table "test".
Now while inserting if duplicate row comes then the same row should get updated instead insert.
How can i achieve this.
Is it possible by dup_val_on_index?
Please help.
First create a copy of the above table without any KEY Columns and follow
Step 1: truncate the table first whenever you encounter a bunch of insert statement comes
Step 2: INSERT the above truncated tables
Step 3: Execute the MERGE statement like below
MERGE INTO TABLE_MAIN M
USING TABLE_MAIN_COPY C
ON (m.id = c.id)
WHEN MATCHED THEN UPDATE SET M.somecol = c.somecol
WHEN NOT MATCHED THEN INSERT (m.id, m.somecol)
VALUES (c.id, c.somecol);
You may incur error while on merger ORA-30926: unable to get a stable set of rows in the source tables when there is two or more rows while on update.
you may avoid that using the GROUP function related to id or like ORA-30926: unable to get a stable set of rows in the source tables
I have this table in an Oracle DB which has a primary key defined on 3 of the data columns. I want to drop the primary key constraint to allow rows with duplicate data for those columns, and create a new column, 'id', to contain an auto-incrementing integer ID for these rows. I know how to create a sequence and trigger to add an auto-incrementing ID for new rows added to the table, but is it possible to write a PL/SQL statement to add unique IDs to all the rows that are already in the table?
Once you have created the sequence:
update mytable
set id = mysequence.nextval;
If you're just using an integer for a sequence you could update the id with the rownum. e.g.
update
table
set id = rownum
You then need to reset the sequence to the next valid id.
Is this what you need?
UPDATE your_table
SET id = your_seq.nextval;
This assumes you don't care what order your primary keys are in.
First you should check your PCTFREE... is there enough room for every row to get longer?
If you chose a very small PCTFREE or your data has lots of lenght-increasing updates, you might begin chaining every row to do this as an update.
You almost certainly better to do this as a CTAS.
Create table t2 as select seq.nextval, t1.* from t1.
drop t1
rename t2 to t1.