I would like to do an INSERT / SELECT, this means INSERT in the TARGET_TABLE the records of the SOURCE_TABLE, with this assumption:
The SOURCE and the TARGET table have only a SUBSET of common columns, this means in example:
==> The SOURCE TABLE has ALPHA, BETA and GAMMA columns;
==> The TARGET TABLE has BETA, GAMMA and DELTA columns.
What is the most efficient way to produce INSERT / SELECT statements, respecting the assumption that not all the target columns are present in the source table?
The idea is that the PL/SQL script CHECKS the columns in the source table and in the target table, makes the INTERSECTION, and then produces a dynamic SQL with the correct list of columns.
Please assume that the columns present in the target table, but not present in the source table, have to be left NULL.
I wish to extract the data from SOURCE into a set of INSERT statements for later insertion into the TARGET table.
You can assume that the TARGET table has more columns than the SOURCE table, and that all the columns in the SOURCE table are present in the TARGET table in the same order.
Thank you in advance for your useful suggestions!
In Oracle, You can get common columns with this SQL query:
select column_name
from user_tab_columns
where table_name = 'TABLE_1'
intersect
select column_name
from user_tab_columns
where table_name = 'TABLE_2'
Then you iterate a cursor with the mentioned query to generate a comma separated list of all values returned. Put that comma separated string into a varchar2 variable named common_fields. Then, you can:
sql_sentence := 'insert into TABLE_1 (' ||
common_fields ||
') select ' ||
common_fields ||
' from TABLE_2';
execute immediate sql_sentence;
Related
Given the following example:
BEGIN
FOR r IN (
SELECT * FROM table_one WHERE change_id = 0
) LOOP
r.change_id := -1;
INSERT INTO table_one VALUES r;
END LOOP;
END;
This inserts new rows to table_one with the exact same content, except the intended change on column change_id to the value -1. I don't have to specify the columns inside of the script as I have to in an INSERT INTO table_one (change_id, ...) SELECT -1, ... FROM table_one WHERE change_id=0;
It works perfectly fine. But how to modify this script to work with a list of tables? The internal structure of those tables are different, but all of them have the necessary column change_id.
Of course the easiest solution would be to copy and paste this snippet x-times and replace the fix table name inside. But is there an option to work with a list of tables in an array?
My approach was like this:
DECLARE
TYPE tablenamearray IS VARRAY(30) OF VARCHAR2(30);
tablenames tablenamearray;
BEGIN
tablenames := tablenamearray('TABLE_ONE', 'TABLE_TWO', 'TABLE_THREE'); -- up to table 30...
FOR i IN tablenames.first..tablenames.last LOOP
/* Found no option to use tablenames(i) here with dynamic SQL */
END LOOP;
END;
Note: There is no technical primary key like an id with a sequence behind. The primary key is build by three columns incl. the change_id column.
You cannot create a SQL statement where the statement is not known at parse time. So, you cannot have a variable as a table name. What you're looking for is Dynamic SQL, which is a fairly complicated topic, but basically you're going to wind up building a SQL statement with DBMS_SQL or running a statement as a string with EXECUTE IMMEDIATE.
Could you please tell me how to compare differences between table and my select query and insert those results in separate table? My plan is to create one base table (name RESULT) by using select statement and populate it with current result set. Then next day I would like to create procedure which will going to compare same select with RESULT table, and insert differences into another table called DIFFERENCES.
Any ideas?
Thanks!
You can create the RESULT_TABLE using CTAS as follows:
CREATE TABLE RESULT_TABLE
AS SELECT ... -- YOUR QUERY
Then you can use the following procedure which calculates the difference between your query and data from RESULT_TABLE:
CREATE OR REPLACE PROCEDURE FIND_DIFF
AS
BEGIN
INSERT INTO DIFFERENCES
--data present in the query but not in RESULT_TABLE
(SELECT ... -- YOUR QUERY
MINUS
SELECT * FROM RESULT_TABLE)
UNION
--data present in the RESULT_TABLE but not in the query
(SELECT * FROM RESULT_TABLE
MINUS
SELECT ... );-- YOUR QUERY
END;
/
I have used the UNION and the difference between both of them in a different order using MINUS to insert the deleted data also in the DIFFERENCES table. If this is not the requirement then remove the query after/before the UNION according to your requirement.
-- Create a table with results from the query, and ID as primary key
create table result_t as
select id, col_1, col_2, col_3
from <some-query>;
-- Create a table with new rows, deleted rows or updated rows
create table differences_t as
select id
-- Old values
,b.col_1 as old_col_1
,b.col_2 as old_col_2
,b.col_3 as old_col_3
-- New values
,a.col_1 as new_col_1
,a.col_2 as new_col_2
,a.col_3 as new_col_3
-- Execute the query once again
from <some-query> a
-- Outer join to detect also detect new/deleted rows
full join result_t b using(id)
-- Null aware comparison
where decode(a.col_1, b.col_1, 1, 0) = 0
or decode(a.col_2, b.col_2, 1, 0) = 0
or decode(a.col_3, b.col_3, 1, 0) = 0;
I am using Toad for oracle 12c. I need to copy a table and data (40M) from one shcema to another (prod to test). However there is an unique key(not the PK for this table) called record_Id col which has something data like this 3.000*******19E15. About 2M rows has same numbers(I believe its because very large number) which are unique in prod. When I try to copy it violets the unique key of that col. I am using toad "export data to another schema" function to copy the data.
when I execute query in prod
select count(*) from table_name
OR
select count(distinct(record_id) from table_name
Both query gives the exact same numbers of data.
I don't have DBA permission. How do I copy all data without violating unique key of the table.
Thanks in advance!
You can use UPSERT for decisional INSERT or UPDATE or you may write small procedure for this.
you may consider to use NOT EXISTS, but your data is big and it might not be resource efficient.
insert into prod_tab
select * from other_tab t1 where NOT exists (
select 1 from prod_tab t2 where t1.id = t2.id
);
In Oracle you can use a MERGE query for that.
The following query proceeds as follows for each data row :
if the source record_id does not yet exist in the target table, a new record is inserted
else, the existing record is updated with source values
For the sake of the example, I assumed that there are two other columns in the table : column1 and column2.
MERGE INTO target_table t1
USING (SELECT * from source_table t2)
ON (t1.record_id = t2.record_id)
WHEN MATCHED THEN UPDATE SET
t1.column1 = t2.column1,
t1.column2 = t2.column2
WHEN NOT MATCHED THEN INSERT
(record_id, column1, column2) VALUES (t2.record_id, t2.column1, t2.column2)
I created the following table:
Create table temp.test(c1 VARCHAR2(10 BYTE));
I was trying to use CHAR_USED to determine whether the column size is in BYTES or CHARS but all I am getting back is '0 rows fetched from 1 column'. The database version i am using is Oracle 11g. Does anyone have a clue as to why it is not return the semantic length information for this table?
The query used are as follows:
select CHAR_USED from all_tab_columns where table_name='temp.test'
select CHAR_USED from all_tab_columns where table_name='test' and owner = 'temp'
Assuming that you are not using case-sensitive identifiers (which you are not and should not), object names are stored in the data dictionary in upper case. So when you query a table like all_tab_columns, you'd need to use upper-case
SELECT column_name, char_used
FROM all_tab_columns
WHERE table_name = 'TEST'
AND owner = 'TEMP'
I want to verify that the data in 2 CLOB columns is the same on 2 different instances. If these were VARCHAR2 columns, I could use a MINUS or a join to determine if rows were in one instance or the other. Unfortunately, Oracle does not allow you to perform set operations on CLOB columns.
How do I compare 2 CLOB columns, one of which is in my local instance and one that is in a remote instance?
Example table structure:
CREATE OR REPLACE TABLE X.TEXT_TABLE
( ID VARCHAR2,
NAME VARCHAR2,
TEXT CLOB
);
You can use an Oracle global temporary table to pull the CLOBs over to your local instance temporarily. You can then use the DBMS_LOB.COMPARE function to compare the CLOB columns.
If this query returns any rows, the CLOBs are different (more or less characters, newlines, etc) or one of the rows exists in only one of the instances.
--Create temporary table to store the text in
CREATE GLOBAL TEMPORARY TABLE X.TEMP_TEXT_TABLE
ON COMMIT DELETE ROWS
AS
SELECT * FROM X.TEXT_TABLE#REMOTE_DB;
--Use this statement if you need to refresh the TEMP_TEXT_TABLE table
INSERT INTO X.TEMP_TEXT_TABLE
SELECT * FROM X.TEXT_TABLE#REMOTE_DB;
--Do the comparision
SELECT DISTINCT
TARGET.NAME TARGET_NAME
,SOURCE.NAME SOURCE_NAME
,DBMS_LOB.COMPARE (TARGET.TEXT, SOURCE.TEXT) AS COMPARISON
FROM (SELECT ID, NAME, TEXT FROM X.TEMP_TEXT_TABLE) TARGET
FULL OUTER JOIN
(SELECT ID, NAME, TEXT FROM X.TEXT_TABLE) SOURCE
ON TARGET.ID = SOURCE.ID
WHERE DBMS_LOB.COMPARE (TARGET.TEXT, SOURCE.TEXT) <> 0
OR DBMS_LOB.COMPARE (TARGETTEXT, SOURCE.TEXT) IS NULL;
You can use DBMS_SQLHASH to compare the hashes of the relevant data. This should use significantly less IO than moving and comparing the CLOBs. The query below will just tell you if there are any differences in the entire table, but you can narrow it down.
select sys.dbms_sqlhash.gethash(sqltext => 'select text from text_table'
,digest_type => 1/*MD4*/) from dual
minus
select sys.dbms_sqlhash.gethash(sqltext => 'select text from text_table#remoteDB'
,digest_type => 1/*MD4*/) from dual;