I have a table in a database created in oracle 10G. It contains a column of type 'VARCHAR' and stores date as string in this format-> 'dd-mon-yyyy' eg: '12-aug-2008'. Now I want to change the datatype of this column from VARCHAR to DATE. but when i perfrom this query->
ALTER TABLE sales_order
MODIFY COLUMN delivery_date DATE;
I get following error
ORA-00905: missing keyword
I have also tried :
ALTER TABLE sales_order
ALTER COLUMN delivery_date DATE;
I got the error :
ORA-01735: invalid ALTER TABLE option
However when i try to add a fresh column with DATE datatype it works fine.
example :
ALTER TABLE sales_order
ADD delivery DATE;
So, can anybody suggest me a way to change the datatype without deleting the column and its data.
It's the first one, with a slight modification:
ALTER TABLE sales_order MODIFY (delivery_date DATE);
But I'm not sure that will work for those particular datatypes and it also may not work depending on the current data.
You may find it necessary in that case to:
create a new column X of date type.
populate X based on the old column (may need several passes of data fix-ups to work).
delete old column.
rename X to old column name.
Although its a pretty old question, I'll put my solution here for people seeking for a solution:
Here's my solution and it works perfectly.
ALTER TABLE `sales_order` CHANGE `delivery_date` `delivery_date` DATE;
Thank you
modify a column then syntax is:-
alter table table_name modify column_name datatype;
but when you modify the column datatype column must be empty
Thanks for the hints! This got it for me.
alter table Table_Name
Alter column Column_Name datatype
GO
I too was needing to change from a VARCHAR to a date. I am working in SQL 2008 R2. I have found that if I bring in dates as a char or varchar and then change the type to date or datetime, I can catch time/date problems more easily.
THIS STATEMENT WILL FAIL IF YOUR DATA HAS ANY BAD DATES. (I break the date down into sections to find the bad date so I can correct and then I can alter the column type.)
Alternatively, you could create a new column, in which the data type is DATE. then pass the data in your varchar as a date .then drop your initial column and finally rename your new column to what it was initially...code below.
ALTER TABLE my_table ADD (new_col DATE);
UPDATE my_table SET new_col=TO_DATE(old_col,'MM/DD/YYYY');
ALTER TABLE my_table DROP (old_col);
ALTER TABLE my_table RENAME COLUMN new_col TO old_col;
alter table employee add (DOB varchar(10));
if you add a column with datatype varchar and if you want to modify the datatype of DOB then you can use this command ->
alter table employee modify(DOB date);
Now the table is modified.
Related
I am using a reporting database which consists of 20 tables on SQL Server. In marketing table I have a column report_date which is currently a varchar(255). It is basically a date formatted in a way 2017-12-12. I want to change the type of this column to a date. I’m running this script but getting errors. The script is down below:
USE [reporting].[dbo].[marketing]
GO
SELECT CONVERT(date, 'report_date');
These are the errors I’m getting.
Msg 911, Level 16, State 1, Line 1
Database 'dbo' does not exist. Make sure that the name is entered correctly.
Msg 241, Level 16, State 1, Line 3
Conversion failed when converting date and/or time from character string.
How should I adjust the script?
If you want to change the column's data type (and you should) then you need to use an alter table statement. Your first error message is because of the USE directive - it should be
USE [reporting]
GO
Your second error message is because 'report_date' is a string constant, not a column name.
The select statement should be
SELECT CAST(report_date as date) -- Don't use Convert without the style argument....
FROM [dbo].[marketing]
Note that if you have even a single value that can't be converted to date you will get the second error again.
Basically I would recommend first making sure that the select statement completes without any exceptions, and only then alter the table:
USE reporting
GO
ALTER TABLE [dbo].[marketing]
ALTER COLUMN report_date DATE
GO
TRY THIS:
SELECT CONVERT(DATE, report_date) --If only for comparison
ALTER TABLE marketing ALTER COLUMN report_date DATE --If want to change in the table
The proper way to do this is like;
ALTER TABLE reportin.dbo.marketing ALTER COLUMN 'report_date' date
And you can check this How do you change the datatype of a column in MS SQL?
"Convert" is used for conversion from one datatype to other in select queries, you need to use alter statement for altering database columns and also
USE [databasename] is enough, so rewriting your query here :
USE [reporting]
GO
ALTER TABLE marketing ALTER COLUMN ReportDate DATE
Slow, but safe way is to:
Create a new column (ALTER TABLE dbo.MyTable ADD MyNewColumn DATE NULL;)
Update the new column using the old one (UPDATE dbo.MyTable SET MyNewColumn = CONVERT(DATE, MyColumn);)
Drop the old column (ALTER TABLE dbo.MyTable DROP MyColumn;) - Alternatively, you can rename this column instead and keep it as is)
Rename the new column (EXEC sp_rename 'dbo.MyTable.MyNewColumn', 'MyColumn', 'COLUMN';)
You might have to drop indexes beforehand, but this method (and it's alterations) help to prevent data loss.
If you encounter an error during casting, you should eliminate those values from the update (by for example adding a WHERE clause) and investigate them manually.
If you are using SQL Server 2012 or newer, you can use TRY_CONVERT() to ignore the values which cannot be converted to DATE. In this case you will have NULL in your new column.
Before you do anything, make sure, that all applications and code which is working with this column can handle the changes.
Notes
You might want to rebuild the table/indexes after a change like this.
How can I change DATA TYPE of a column from number to varchar2 without deleting the table data?
You can't.
You can, however, create a new column with the new data type, migrate the data, drop the old column, and rename the new column. Something like
ALTER TABLE table_name
ADD( new_column_name varchar2(10) );
UPDATE table_name
SET new_column_name = to_char(old_column_name, <<some format>>);
ALTER TABLE table_name
DROP COLUMN old_column_name;
ALTER TABLE table_name
RENAME COLUMN new_column_name TO old_coulumn_name;
If you have code that depends on the position of the column in the table (which you really shouldn't have), you could rename the table and create a view on the table with the original name of the table that exposes the columns in the order your code expects until you can fix that buggy code.
You have to first deal with the existing rows before you modify the column DATA TYPE.
You could do the following steps:
Add the new column with a new name.
Update the new column from old column.
Drop the old column.
Rename the new column with the old column name.
For example,
alter table t add (col_new varchar2(50));
update t set col_new = to_char(col_old);
alter table t drop column col_old cascade constraints;
alter table t rename column col_new to col_old;
Make sure you re-create any required indexes which you had.
You could also try the CTAS approach, i.e. create table as select. But, the above is safe and preferrable.
The most efficient way is probably to do a CREATE TABLE ... AS SELECT
(CTAS)
alter table table_name modify (column_name VARCHAR2(255));
Since we can't change data type of a column with values, the approach that I was followed as below,
Say the column name you want to change type is 'A' and this can be achieved with SQL developer.
First sort table data by other column (ex: datetime).
Next copy the values of column 'A' and paste to excel file.
Delete values of the column 'A' an commit.
Change the data type and commit.
Again sort table data by previously used column (ex: datetime).
Then paste copied data from excel and commit.
I want to update an empty table , which has a column of type timestamp to varbinary(8)
I used the following command
ALTER TABLE Notification ALTER COLUMN RowRevisionID varbinary(8)
and I get and an error
Cannot alter column 'RowRevisionID' because it is 'timestamp'.
How can I change a timestamp column type?
I do not wish to drop the column an add a new one , because that will create a column at the end , and I wish to preserve column order to use this table in an INSERT INTO
You unfortunately cannot make a change to a timestamp column, as the error implies; you are stuck with what you have. Also, each table can only have one timestamp column, so you cannot duplicate the column in any solution.
Your best bet (depending on the size of the table) might be to copy the data into a staging table (using SELECT * INTO MyTempTable FROM OriginalTable syntax to preserve the timestamp values), then drop and recreate the original table with the desired columns in the desired order and reinsert the data, or you could add a new VARBINARY(8) column to the existing table and drop the timestamp column, preserving the original table. There are probably other solutions along the same lines as these, but all will require a new column, rather than an ALTER COLUMN script.
You are looking for:
ALTER TABLE Notification DROP RowRevisionID;
and
ALTER TABLE Notification ADD RowRevisionID varbinary(8) AFTER myOtherColumn;
I'm trying to add a virtual column of date type which adds five years to another date column:
ALTER TABLE AU_Ventes ADD (
DateVente date NOT NULL,
DateFinGarantie date As(ADD_MONTHS(DateVente, 60))
);
But I get the error: "%s: invalid identifier". Perhaps I can't use the ADD_MONTHS function in an ALTER TABLE. What can I do to accomplish what I want to do?
Thanks.
Although you can define a virtual column in a create table statement, where you are obviously creating it at the same time as the column it is based on, you can't define both in the same alter table statement. You have to do it in two steps:
ALTER TABLE AU_Ventes ADD DateVente date NOT NULL;
ALTER TABLE AU_Ventes ADD DateFinGarantie date
As(ADD_MONTHS(DateVente, 60));
Not sure that's an intentional restriction, but it's how it works.
Trivial SQL Fiddle to show this working.
I have database and some text fields are CLOB type, I need to change most of these into VARCHAR2.
Have tried to do that using SQL Developer tool, by clicking edit on table, but get error like this one:
The following SQL statement failed:
ALTER TABLE TBL_PEOPLE MODIFY (PERSON VARCHAR2(150) )
Want to ask, how can this change be done
You can't, directly. The code you tried will have got an `ORA-22859, presumably. (It's helpful to show the actual errors you get, of course).
You'll need to add a new varchar2 column; copy the data across - or a substring of it if it might be larger than the new column you're creating; drop the clob column. You can rename the columns so it looks fairly transparent.
As in this SQL Fiddle:
alter table tbl_people rename column person to clob_person;
alter table tbl_people add (person varchar2(150));
update tbl_people set person = clob_person;
alter table tbl_people drop column clob_person;
Obviously don't drop the old column until you're sure the data has copied without errors. Also take into account any constraints, indexes, etc. that might exist in the old column; they will need to be recreated. And anything that references the old column will have been invalidated - generally procedures will recompile themselves on next use.
So be careful, test it first, and plan some down time.
ALTER TABLE tablename ADD (FIELD_LIST_TEMP VARCHAR2);
UPDATE tablename SET FIELD_LIST_TEMP = FIELD_LIST;
ALTER TABLE tablename DROP COLUMN FIELD_LIST;
ALTER TABLE tablename RENAME COLUMN FIELD_LIST_TEMP TO FIELD_LIST;
Here FIELD_LIST existing column which is defined it as CLOB. With above query it will change from CLOB to VARCHAR2.