i am trying to get all extra data from one data base and trying to insert into another.
But i want to omit the column name and am trying to make only the table name as hard coded to achieve this. But we have some fields which are system generated in a table like an id which is not that necessary a data but still will create a integrity issue. How can i do a insert of just the wanna be details omitting those above columns, the names of the columns to omit also changes.. I can't do a total insert, just the addition of some extra data.
so far i have come to this.
while 1=1
begin
if exists(select 1 from db1.table1 not in (select * from db2.table1)
begin
insert into db2.table1 (columns) select (columns) from db1.table1
end
if(rowCount=0)
break
end
please advise how i can optimize this to get the least possible hard coding
Have left the pk part intentionally, as
the query being big.
If you want to something like:
insert into TAB
select * from TAB2
or
insert into TAB
select col1,col2 from TAB2
or
insert into TAB (col1,col2)
select * from TAB2
where TAB1 and TAB2 have different count or type of columns it's not possible, because it will generate an error.
Related
Need to add two following insert statements:
insert into table1(schema, table_name, table_alias)
values ('ref_owner','test_table_1','tb1');
insert into table1(schema, table_name, table_alias)
values ('dba_owner','test_table_2','tb2');
Question is how can I make those two insert statements re-runnable meaning, if those two insert statement are compiled again, it should throw row exists error or something along those lines...?
Additional notes:
1. I've seen examples of Merge in Oracle however, thats only when you're using two tables to match records. In this case im only using a single table.
2. The table does not have any primary, unique or foreign keys - only check constraints on one of the columns.
Any help is highly appreciated.
You can use a MERGE statement, as follows:
MERGE into table1 t1
USING (SELECT 'ref_owner' AS SCHEMA_NAME, 'test_table_1' AS TABLE_NAME, 'tb1' AS ALIAS_NAME FROM DUAL
UNION ALL
SELECT 'dba_owner', 'test_table_2', 'tb2' FROM DUAL) d
ON (t1.SCHEMA = d.SCHEMA_NAME AND
t1.TABLE_NAME = d.TABLE_NAME)
WHEN NOT MATCHED THEN
INSERT (SCHEMA, TABLE_NAME, TABLE_ALIAS)
VALUES (d.SCHEMA_NAME, d.TABLE_NAME, d.ALIAS_NAME)
Best of luck.
You should have a primary key, especially when you want to check for duplicate records and data integrity.
Provide a primary key for your table, or, if you somehow do not want to do that, create a unique constraint for all of the columns in the table, so no duplicate rows are possible.
I have a specific scenario where i have to insert two new columns in an existing table in Oracle. I can not do the dropping and recreating the table. So can it be achieved by any means??
Amit-
I don't believe you can add a column anywhere but at the end of the table once the table is created. One solution might be to try this:
CREATE TABLE MY_TEMP_TABLE AS
SELECT *
FROM TABLE_TO_CHANGE;
Drop the table you want to add columns to:
DROP TABLE TABLE_TO_CHANGE;
It's at the point you could rebuild the existing table from scratch adding in the columns where you wish.
Let's assume for this exercise you want to add the columns named "COL2 and COL3".
Now insert the data back into the new table:
INSERT INTO TABLE_TO_CHANGE (COL1, COL2, COL3, COL4)
SELECT COL1, 'Foo', 'Bar', COL4
FROM MY_TEMP_TABLE;
When the data is inserted into your "new-old" table, you can drop the temp table.
DROP TABLE MY_TEMP_TABLE;
This is often what I do when I want to add columns in a specific location. Obviously if this is a production on-line system, then it's probably not practical, but just one potential idea.
-CJ
In 12c you can make use of the fact that columns which are set from invisible to visible are displayed as the last column of the table:
Tips and Tricks: Invisible Columns in Oracle Database 12c
Maybe that is the 'trick' #jeffrey-kemp was talking about in his comment, but the link there does not work anymore.
Example:
ALTER TABLE my_tab ADD (col_3 NUMBER(10));
ALTER TABLE my_tab MODIFY (
col_1 invisible,
col_2 invisible
);
ALTER TABLE my_tab MODIFY (
col_1 visible,
col_2 visible
);
Now col_3 would be displayed first in a SELECT * FROM my_tab statement.
Note: This does not change the physical order of the columns on disk, but in most cases that is not what you want to do anyway. If you really want to change the physical order, you can use the DBMS_REDEFINITION package.
Although this is somewhat old I would like to add a slightly improved version that really changes column order. Here are the steps (assuming we have a table TAB1 with columns COL1, COL2, COL3):
Add new column to table TAB1:
alter table TAB1 add (NEW_COL number);
"Copy" table to temp name while changing the column order AND rename the new column:
create table tempTAB1 as select NEW_COL as COL0, COL1, COL2, COL3 from TAB1;
drop existing table:
drop table TAB1;
rename temp tablename to just dropped tablename:
rename tempTAB1 to TAB1;
You (still) can not choose the position of the column using ALTER TABLE: it can only be added to the end of the table. You can obviously select the columns in any order you want, so unless you are using SELECT * FROM column order shouldn't be a big deal.
If you really must have them in a particular order and you can't drop and recreate the table, then you might be able to drop and recreate columns instead:-
First copy the table
CREATE TABLE my_tab_temp AS SELECT * FROM my_tab;
Then drop columns that you want to be after the column you will insert
ALTER TABLE my_tab DROP COLUMN three;
Now add the new column (two in this example) and the ones you removed.
ALTER TABLE my_tab ADD (two NUMBER(2), three NUMBER(10));
Lastly add back the data for the re-created columns
UPDATE my_tab SET my_tab.three = (SELECT my_tab_temp.three FROM my_tab_temp WHERE my_tab.one = my_tab_temp.one);
Obviously your update will most likely be more complex and you'll have to handle indexes and constraints and won't be able to use this in some cases (LOB columns etc). Plus this is a pretty hideous way to do this - but the table will always exist and you'll end up with the columns in a order you want. But does column order really matter that much?
I created a table using select with a union, as follows:
create table tableC as
select column1, column2 from tableA
union all
select column1, column2 from tableB
The resulting table (tableC) has inherited none of the constraints from tableA or tableB. Why weren't the constraints copied to the new table?
Using select ... as ... to create a table never copies constraints. If you want the new table to inherit constraints from the original tables, you must create the new constraints manually.
As #Davek points out, not null constraints will get copied from a single table select ... as .... I imagine that's because they are both column attributes and constraints. However, once the column has more than one source, it is reasonable that Oracle would not try to apply that constraint.
In response to the follow-up question "would it be possible to give tableC the same constraints either from tableA or tableB, after a CTAs?":
Of course it's possible, but there's no single command to do it. You could write a procedure that used dynamic SQL to copy the constraints. However, unless you're looking to automate this behavior, it'll generally be easier to extract the DDL using an IDE and change the table name.
I'm using Amazon's Elastic MapReduce and I have a hive table created based on a series of log files stored in Amazon S3 and split in folders by day like so:
data/day=2011-09-01/log_file.tsv
data/day=2011-09-02/log_file.tsv
I am currently trying to create an additional table which filters out some unwanted activity in these log files but I can't figure out how to do this and keep getting errors such as:
FAILED: Error in semantic analysis: need to specify partition columns because the destination table is partitioned.
If my initial table create statement looks something like this:
CREATE EXTERNAL TABLE IF NOT EXISTS table1 (
... fields ...
)
PARTITIONED BY ( DAY STRING )
ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t'
LOCATION 's3://bucketname/data/';
That initial table works fine and I've been able to query it with no problems.
How then should I create a new table that shares the structure of the previous one but simply filters out data? This doesn't seem to work.
CREATE EXTERNAL TABLE IF NOT EXISTS table2 LIKE table1;
FROM table1
INSERT OVERWRITE TABLE table2
SELECT * WHERE
col1 = '%somecriteria%' AND
more criteria...
;
As I've stated above, this returns:
FAILED: Error in semantic analysis: need to specify partition columns because the destination table is partitioned.
Thanks!
This always works for me:
CREATE EXTERNAL TABLE IF NOT EXISTS table2 LIKE table1;
INSERT OVERWRITE TABLE table2 PARTITION (day) SELECT col1, col2, ..., day FROM table1;
ALTER TABLE table2 RECOVER PARTITIONS;
Notice that I've added 'day' as a column in the SELECT statement. Also notice that there is an ALTER TABLE line which is necessary for Hive to become aware of the partitions that were newly created in table2.
I have never used the like option.. so thanks for showing me that. Will that actually create all of the partitions that the first table has as well? If not, that could be the issue. You could try using dynamic partitions:
create external table if not exists table2 like table1;
insert overwrite table table2 partition(part) select col1, col2 from table1;
Might not be the best solution, as I think you have to specify your columns in the select clause (as well as the partition column in the partition clause).
And, you must turn on dynamic partitioning.
I hope this helps.
Hi I have a database with loads of columns and I want to insert couple of records for testing, now in order to insert something into that database I'd have to write large query .. is it possible to do something like this
INSERT INTO table (SELECT FROM table WHERE id='5') .. I try to insert the row with ID 5 but I think this will create a problem because it will try to duplicate a record, is it possible to change this ID 5 to let say 1000 then I'd be able to insert data without writing complex query and while doing so avoiding replication of data .. tnx
In PL/SQL you can do something like this:
declare
l_rec table%rowtype;
begin
select * into l_rec from table where id='5';
l_rec.id := 1000;
insert into table values l_rec;
end;
If you have a trigger on the table to handle the primary key from a sequence (:NEW.id = seq_sequence.NEXTVAL) then you should be able to do:
INSERT INTO table
(SELECT columns_needed FROM table WHERE whatever)
This will allow you to add in many rows at one (the number being limited by the WHERE clause). You'll need to select the columns that are required by the table to be not null or not having default values. Beware of any unique constraints as well.
Otherwise you'll be looking at PL/SQL or some other form of script to insert multiple rows.
For each column that has no default value or you want to insert the values other than default, you will need to provide the explicit name and value.
You only can use an implicit list (*) if you want to select all columns and insert them as they are.
Since you are changing the PRIMARY KEY, you need to enumerate.
However, you can create a before update trigger and change the value of the PRIMARY KEY in this trigger.
Note that the trigger cannot reference the table itself, so you will need to provide some other way to get the unique number (like a sequence):
CREATE TRIGGER trg_mytable_bi BEFORE INSERT ON mytable FOR EACH ROW
BEGIN
:NEW.id := s_mytable.nextval;
END;
This way you can use the asterisk but it will always replace the value of the PRIMARY KEY.