I have added a new column in table, when I select this table with schema name, new column shows, when i select this column without mention of schema name, SQL does not identify new column, so basically:
Select new_column From schema.table works
Select new_column from table does not work
Please tell me why this is happening & how to correct this, i want this column available without mentioning schema name.
If you are not getting new column when you are selecting from table whithout schema name, then this means that that schema name is not default and you have 2 tables with that name both in default and mensioned schema. You can have tables with same name in different schemas.
It turned out that column is not getting selected because I am querying a view, not a table, and I need to add this column to view as well.
Confusion occurred because in previous versions of product(Dynamics AX) they(Microsoft) did not apply schema to database objects, now they added schema & created a view for backward compatibility.
Related
I'm using a blue-green deployment strategy with expand contract database pattern. To achieve that on my database deploy schema I've setted the property BlockOnPossibleDataLoss=true because on Expand phase I can modify my database without any break change with the old version.
I had a column that is not necessary anymore so I followed those steps:
I've changed this column to allow null values
Then my new records don't fill this column anymore
I ran a script that setted null for this column to all table records
Now I need to delete this column, but even with all records with NULL value for this column I can't because I got this error:
Rows were detected. The schema update is terminating because data loss
might occur.'
How can I delete this column even using BlockOnPossibleDataLoss=true?
Create the table with the new schema (without the column you wan't to drop) with a temporary name. Something like tmp_YourTable (Not a temporary table)
Insert all data from the source table, to the newly created table
Drop the source table
Rename the new table, to the old table name. EXEC sp_rename 'tmp_YourTable', 'YourTable';
I need to drop all columns in an existing table in SQL Server. It is possible to delete columns by specifying each column name. I want to delete every column without specifying column name. I am looking for something like
ALTER TABLE tblUser DROP COLUMN *;
Is there any known way to do this?
Answering your question literally, no you can't. If you try to remove the last column, SQL Server will throw the following error:
Msg 4923, Level 16, State 1, Line 12
ALTER TABLE DROP COLUMN failed because 'Id' is the only data column in table 'NoColumns'. A table must have at least one data column.
As such, if you actually want to solve your problem, whatever it is, it would be best to voice the initial problem and not the solution you decided to pursue.
Instead remove all the columns, you could drop the table
DROP TABLE TABLENAME
Or You can mention all the column names in Alter query
ALETR TABLE TableName DROP COLUMN Column1, Column2, Column3....ColumnN
I'm looking to rename a column in PostgreSQL with no downtime. My code will depend on the column name so I'd like to duplicate the column with a new name along with the contents and data type of the existing column, then push the code changes before deleting the original column. Is there a Postgres command for duplicating a column with its contents into the same table?
I found a relatively simple way to do this in two commands:
ALTER TABLE mytable ADD COLUMN "new_column" <DATA TYPE STUFF FROM OLD COLUMN>;
UPDATE mytable SET new_column = old_column;
Didn't realise it would be this easy. I didn't lock the table as that column isn't used too frequently so a small slowdown would be okay.
I have situation where I need to change the order of the columns/adding new columns for existing Table in SQL Server 2008.
Existing column
MemberName
MemberAddress
Member_ID(pk)
and I want this order
Member_ID(pk)
MemberName
MemberAddress
I got the answer for the same ,
Go on SQL Server → Tools → Options → Designers → Table and Database Designers and unselect Prevent saving changes that require table re-creation
2- Open table design view and that scroll your column up and down and save your changes.
It is not possible with ALTER statement. If you wish to have the columns in a specific order, you will have to create a newtable, use INSERT INTO newtable (col-x,col-a,col-b) SELECT col-x,col-a,col-b FROM oldtable to transfer the data from the oldtable to the newtable, delete the oldtable and rename the newtable to the oldtable name.
This is not necessarily recommended because it does not matter which order the columns are in the database table. When you use a SELECT statement, you can name the columns and have them returned to you in the order that you desire.
If your table doesn't have any records you can just drop then create your table.
If it has records you can do it using your SQL Server Management Studio.
Just click your table > right click > click Design then you can now arrange the order of the columns by dragging the fields on the order that you want then click save.
Best Regards
I tried this and dont see any way of doing it.
here is my approach for it.
Right click on table and Script table for Create and have this on
one of the SQL Query window,
EXEC sp_rename 'Employee', 'Employee1' -- Original table name is Employee
Execute the Employee create script, make sure you arrange the columns in the way you need.
INSERT INTO TABLE2 SELECT * FROM TABLE1.
-- Insert into Employee select Name, Company from Employee1
DROP table Employee1.
Relying on column order is generally a bad idea in SQL. SQL is based on Relational theory where order is never guaranteed - by design. You should treat all your columns and rows as having no order and then change your queries to provide the correct results:
For Columns:
Try not to use SELECT *, but instead specify the order of columns in the select list as in: SELECT Member_ID, MemberName, MemberAddress from TableName. This will guarantee order and will ease maintenance if columns get added.
For Rows:
Row order in your result set is only guaranteed if you specify the ORDER BY clause.
If no ORDER BY clause is specified the result set may differ as the Query Plan might differ or the database pages might have changed.
Hope this helps...
This can be an issue when using Source Control and automated deployments to a shared development environment. Where I work we have a very large sample DB on our development tier to work with (a subset of our production data).
Recently I did some work to remove one column from a table and then add some extra ones on the end. I then had to undo my column removal so I re-added it on the end which means the table and all references are correct in the environment but the Source Control automated deployment will no longer work because it complains about the table definition changing.
The real problem here is that the table + indexes are ~120GB and the environment only has ~60GB free so I'll need to either:
a) Rename the existing columns which are in the wrong order, add new columns in the right order, update the data then drop the old columns
OR
b) Rename the table, create a new table with the correct order, insert to the new table from the old and delete from the old as I go along
The SSMS/TFS Schema compare option of using a temp table won't work because there isn't enough room on disc to do it.
I'm not trying to say this is the best way to go about things or that column order really matters, just that I have a scenario where it is an issue and I'm sharing the options I've thought of to fix the issue
SQL query to change the id column into first:
ALTER TABLE `student` CHANGE `id` `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT FIRST;
or by using:
ALTER TABLE `student` CHANGE `id` `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT AFTER 'column_name'
I've created a View from a table in another database. I have dbo rights to the databases so viewing and updating is not a problem. This particular View did not have an "id" column. So I added one to the View by using ROW_NUMBER. Now I had a problem with a table, in the same database, not showing up in LightSwitch but that was solved by changing the id column to be NOT NULL. I haven't done any real manipulation in LightSwitch. I'm still in the Import Your Data Source stage (ie. very beginning).
This View, in LightSwitch, is going to be read-only. No updating or deleting. From what I've read, LightSwitch needs a way to determine the PK of a Table or View. It either reads it from the schema (column set as a PK) or finds a column set as NOT NULL and uses that as the PK. Well I can't seem to do either of those things in SQL Server or LightSwitch, so I am stuck as to how to get LightSwitch to "see" my View.
for lightswitch to see your view you must have a primary key on a column of the table your are selecting from.
Example:
create table tbl_test
(
id int identity primary key not null,
value varchar(50)
)
create view vw_test
as
select *
from tbl_test
note:sometimes when you edit the primary key column in the view select statement it may cause lightswitch to not see it
Example:
create view vw_test
select cast(id as varchar(50) id,...
lightswitch would not see the table
Hope this was helpful! :)
What I do in this case is create a view with an ID column equal to the row number. Ensure the column you're basing the ID on is not null using the isnull() or coalesce() functions.
Example:
create view as
select distinct ID = row_number() over (order by isnull(Name,'')),
Name = isnull(Name,'')
from My_Table