I have a table with approximately 90 columns and want to delete all after the 5th. How to delete all columns except first five?
Given that you only want to keep a few columns, the option with least code would be to make a new table with those columns only. You should do this in a transaction to avoid losing data.
Example with two columns:
ALTER TABLE TableName RENAME TO TmpTableName;
CREATE TABLE TableName(Col1 INTEGER, Col2 INTEGER);
INSERT INTO TableName(Col1, Col2) SELECT Col1, Col2 FROM TmpTableName;
DROP TABLE TmpTableName;
Before version 3.35.0, SQLite did not support removing columns, so this was the only possible option.
Related
I need to delete the values from Cost & Remaining column from the below table and insert new values from another table. Can anyone help please?
One possible way is you can delete the columns Cost and Remaining first then you can create it.
CREATE OR REPLACE TABLE `transactions.test_table` AS
SELECT
* EXCEPT (Cost, Remaining)
FROM
`transactions.test_table`;
The above will create the table without those 2 columns. Now you can insert the data from other table by creating the other columns.
A better way to do is as follows:
CREATE OR REPLACE TABLE `transactions.test_table` AS
SELECT
table1.Date, table1.Name, table2.Cost, table2. Remaining
FROM
`transactions.test_table` table1, `transactions.other_table` table2;
i have one table test it has 10 column with 20 rows.
I need to move this data to archive_test table which has 11 column (10 same as test table plus one column is archive date).
when i tried to insert like below its shows error because number of column mismatch.
insert into archive_test
select * from test;
Please suggest the better way to do this.Thanks!
Well, obviously you need to supply values for all the columns, and although you can avoid doing so you should also explicitly state whic value is going to be inserted into which column. If you have an extra column in the target table you either:
Do not mention it
Specify a default value as part of its column definition in the table
Have a trigger to populate it
Specify a value for that column.
eg.
insert into table archive_test (col1, col2, col3 ... col11)
select col1,
col2,
col3,
...
sysdate
from test;
assuming that archive_date is the last column:
INSERT INTO archive_test
SELECT test.*, sysdate
FROM test
This question already has answers here:
How to insert a column in a specific position in oracle without dropping and recreating the table?
(4 answers)
Is there a way to add column at a specified position in Oracle table? [duplicate]
(1 answer)
Closed 9 years ago.
One question
Database: Oracle
This is the stmt (Desc.: chnage type VARCHAR to CLOB)
ALTER TABLE XX
ADD (TEMP_Value CLOB);
UPDATE XX SET TEMP_Value=Value;
COMMIT;
ALTER TABLE XX DROP COLUMN Value;
ALTER TABLE XX
RENAME COLUMN TEMP_Value TO Value;
the problem:
The new clob-column is the last column in the XX table (normally).
If value second was now is the last column, How to change the sequence
I know the following solution and that is not very smart for several of columns, so I want to find a other solution.
create newtable as
select Value, X, XX,..
drop table XX;
rename newtable to XX;
Discussed here
Oracle does not support adding columns in the middle of a table, only adding them to the end, unlike MYSQL ALTER TABLE TABLENAME ADD COL1 AFTER COL2 command. Your database design and app functionality should not depend on the order of columns in the database schema. You can always specify an order in your select statement, after all, which would be best practice.
SELECT * FROM TABLE is not a good practice.
However if for some reason you simply must have a new column in the middle of your table there is a work around.
CREATE TABLE TAB1NEW
AS
SELECT
0 AS COL1,
COL1 AS COL2
FROM
TAB1;
DROP TABLE TAB1 PURGE;
RENAME TAB1NEW TO TAB1;
Where the SELECT 0 AS col1 is your new column and then you specify other columns as needed from your original table. Put the SELECT 0 AS col1 at the appropriate place in the order you want.
Afterwards you may want to run an alter table statement on the column to make sure it's the data type you desire. Remember to put back your constraints, indexes, partition... and whatever as per the original table
I want to select some data using simple sql and insert those data into another table. Both table are same. Data types and column names all are same. Simply those are temporary table of masters table. Using single sql I want to insert those data into another table and in the where condition I check E_ID=? checking part. My another problem is sometime there may be any matching rows in the table. In that time is it may be out sql exception? Another problem is it may be multiple matching rows. That means one E_ID may have multiple rows. As a example in my attachment_master and attachments_temp table has multiple rows for one single ID. How do I solve those problems? I have another problem. My master table data can insert temp table using following code. But I want to change only one column and others are same data. Because I want to change temp table status column.
insert into dates_temp_table SELECT * FROM master_dates_table where e_id=?;
In here all data insert into my dates_temp_table. But I want to add all column data and change only dates_temp_table status column as "Modified". How should I change this code?
You could try this:
insert into table1 ( col1, col2, col3,.... )
SELECT col1, col2, col3, ....
FROM table2 where (you can check any condition here on table1 or table2 or mixed)
For more info have a look here and this similar question
Hope it may help you.
EDit : If I understand your requirement properly then this may be a helpful solution for you:
insert into table1 ( col-1, col-2, col-3,...., col-n, <Your modification col name here> )
SELECT col-1, col-2, col-3,...., col-n, 'modified'
FROM table2 where table1.e_id=<your id value here>
As per your comment in above other answer:
"I send my E_ID. I don't want to matching and get. I send my E_ID and
if that ID available I insert those data into my temp table and change
temp table status as 'Modified' and otherwise don't do anything."
As according to your above statements, If given e_id is there it will copy all the columns values to your table1 and will place a value 'modified' in the 'status' column of your table1
For more info look here
You can use merge statement if I understand your requirement correctly.
Documentation
As I do not have your table structure below is based on assumption, see whether this cater your requirement. I am assuming that e_id is primary key or change as per your table design.
MERGE INTO dates_temp_table trgt
USING (SELECT * FROM master_dates_table WHERE e_id=100) src
ON (trgt.prm_key = src.prm_key)
WHEN NOT MATCHED
THEN
INSERT (trgt.col, trgt.col2, trgt.status)
VALUES (src.col, src.col2, 'Modified');
More information and examples here
insert into tablename( column1, column2, column3,column4 ) SELECT column1,
column2, column3,column4 from anothertablename where tablename.ID=anothertablename.ID
IF multiple values are there then it will return the last result..If not you have narrow your search..
Sybase db tables do not have a concept of self updating row numbers. However , for one of the modules , I require the presence of rownumber corresponding to each row in the database such that max(Column) would always tell me the number of rows in the table.
I thought I'll introduce an int column and keep updating this column to keep track of the row number. However I'm having problems in updating this column in case of deletes. What sql should I use in delete trigger to update this column?
You can easily assign a unique number to each row by using an identity column. The identity can be a numeric or an integer (in ASE12+).
This will almost do what you require. There are certain circumstances in which you will get a gap in the identity sequence. (These are called "identity gaps", the best discussion on them is here). Also deletes will cause gaps in the sequence as you've identified.
Why do you need to use max(col) to get the number of rows in the table, when you could just use count(*)? If you're trying to get the last row from the table, then you can do
select * from table where column = (select max(column) from table).
Regarding the delete trigger to update a manually managed column, I think this would be a potential source of deadlocks, and many performance issues. Imagine you have 1 million rows in your table, and you delete row 1, that's 999999 rows you now have to update to subtract 1 from the id.
Delete trigger
CREATE TRIGGER tigger ON myTable FOR DELETE
AS
update myTable
set id = id - (select count(*) from deleted d where d.id < t.id)
from myTable t
To avoid locking problems
You could add an extra table (which joins to your primary table) like this:
CREATE TABLE rowCounter
(id int, -- foreign key to main table
rownum int)
... and use the rownum field from this table.
If you put the delete trigger on this table then you would hugely reduce the potential for locking problems.
Approximate solution?
Does the table need to keep its rownumbers up to date all the time?
If not, you could have a job which runs every minute or so, which checks for gaps in the rownum, and does an update.
Question: do the rownumbers have to reflect the order in which rows were inserted?
If not, you could do far fewer updates, but only updating the most recent rows, "moving" them into gaps.
Leave a comment if you would like me to post any SQL for these ideas.
I'm not sure why you would want to do this. You could experiment with using temporary tables and "select into" with an Identity column like below.
create table test
(
col1 int,
col2 varchar(3)
)
insert into test values (100, "abc")
insert into test values (111, "def")
insert into test values (222, "ghi")
insert into test values (300, "jkl")
insert into test values (400, "mno")
select rank = identity(10), col1 into #t1 from Test
select * from #t1
delete from test where col2="ghi"
select rank = identity(10), col1 into #t2 from Test
select * from #t2
drop table test
drop table #t1
drop table #t2
This would give you a dynamic id (of sorts)