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.
Related
I want to insert a one or more records in table A.
But same record already existing in records with status Active
CREATE PROCEDURE Test
AS
BEGIN
INSERT INTO A (x,y,z,status)
SELECT data FROM A WHERE some condtion;
... Here i want to update table A status column into 'N', if the inserted data already existing in table A Compared with x,y,z column.
EXCETION
---Handled
END;
You can try this:
MERGE INTO target_table t
USING source_table s
ON (t.id = s.id)
WHEN MATCHED THEN
UPDATE SET t.col1 = s.col1
WHEN NOT MATCHED THEN
INSERT (col1, col2) VALUES (s.col1, s.col2);
Documentation Link: https://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_9016.htm#SQLRF01606
What you probably want to do is a merge-statement. The merge statement checks if the dataset already exists. In this case you can formulate an update statement. For example, you could update the status. If not, the new dataset will be inserted.
For further information you should hava a look here.
The merge is the way to go. Another approach is first updating all the rows that match the criteria and after do the insert.
However, if your problem is how to differentiate the 2 rows, use the pseudo-column ROWID.
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 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.
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.
I have a problem in indexing in Oracle. Will try to explain my problem with an instance as follows.
I have a table TABLE1 with columns A,B,C,D
another table TABLE2 with columns A,B,C,E,F,H
I have created Indexes for TABLE1
IX_1 A
IX_2 A,B
IX_3 A,C
IX_4 A,B,C
I have created Indexes for TABLE1
IY_1 A,B,C
IY_2 A
when i gave query similar to this
SELECT * FROM TABLE1 T1,TABLE2 T2
WHERE T1.A=T2.A
When i give Explain Plan i got its not getting IX_1 nor IY_2
Its taking IX_4 nor IY_1
why this is not picking right index?
EDITED:
Can anyone help me to know difference between INDEX RANGE SCAN,INDEX UNIQUE SCAN, INDEX SKIP SCAN
I guess SKIP SCAN means when a column is skipped in Composite Index by Oracle
what about others i dont have idea!
The best benefit of indexes is that you can select a few rows from a table without scanning the entire table.
If you ask for too many rows(let's say 30% - depends of many things) the engine will prefer to scan the entire table for those rows.
That's because reading a row using an index is gets an overhead : reading some index blocks, and after that reading table blocks.
In your case, in order to join tables T1 and T2, Oracle needs all the rows from those table. Reading(full) the index will be an unsefull operation, adding unnecesary cost.
UPDATE: A step forward: if you run:
SELECT T1.B, T2.B FROM TABLE1 T1,TABLE2 T2
WHERE T1.A=T2.A
Oracle probably will use the indexes(IX2, IY2), because it does not need to read anything from table, because the values T1.B, T2.B, are in indexes.