Probably a simple answer, but assume I have a table with 3 columns:
ab, cd, ef
I create a new view
SELECT *
FROM tbl
It works. I save the view, SSMS automatically changes the saved version of the view to say:
SELECT dbo.tbl.ab, dbo.tbl.cd, dbo.tbl.ef
How do I keep the saved version of the view to include all columns in tbl rather than explicitly identifying each column?
You can create the view like this:
CREATE VIEW vwTbl
AS
SELECT *
FROM tbl
Then you can query the view to retrieve all columns like:
SELECT * FROM vwTbl
Related
I am trying to create snapshot tables as part of script I run regularly.
At the moment I have to manually enter table names, but I would like to call on a field in the base data table to create the snapshot table name.
For example:
Base Data Table = base_data and contains a field for the month it was created in.
Snapshot table = base_data_month
I have already tried to run this to create an automatically named table...
create table base_data_snapshot_||(select month from base_data) as
select * from base_data
But this gets a syntax error. For reference there is only one month included in the base data.
Has anyone had any success with this before?
Although we cant combine a running create statement with a select but can use select. So, I guess below should work
create table
base_data_snapshot_||t.month
as
( select * from base_data) t
I am using sqlite3.
Suppose I have a view view_intermediate. I would like to create a temporary table from this view. In other words, turn the result of the view into a temporary table.
How should the SQL statement look like to do this?
SQLite supports CREATE TABLE AS..SELECT, so assuming you want the data in the table:
CREATE TABLE myTable AS
SELECT *
FROM view_intermediate;
If you want a table to be created from the view, but don't want the data, you can add a false condition.
CREATE TABLE myTable AS
SELECT *
FROM view_intermediate
WHERE 1=2;
I have a database where a view and a table have same name, when I try to execute query
select * from XXXXXXXXX
from where is this data coming from, view or table? Is there any explicit declaration syntax to tell, to where from select the data?
PS: the DB owner is different so I can't change the structure of view/table or names either.
Objects names are unique per owner, so the table and the view can't be defined for the same owner.
Qualify the table/view name with the right owner.
select * from table_owner.XXXXXXXXX
select * from view_owner.XXXXXXXXX
I have a table 'Goods' with different information about goods (name, price, etc). I need to create a view at the same scheme as table 'Goods' has. But the view must be empty. And when user adds new good to the view it is saved in table 'Goods', but the view remains empty when user opens it next time. So main idea is not to show existing data to the user which has access to the view.
Assuming your on a database system that supports a concept like SQL Server's CHECK OPTION, and you're allowed to create a view that doesn't have that option set, you should be fine:
create table T (ID int not null)
go
create view V
as
select * from T where 1=0
go
select * from V
go
insert into V(ID) values (10)
go
select * from V
go
select * from T
The two selects from V return 0 rows. The select from T returns one row:
ID
----
10
CHECK OPTION:
Forces all data modification statements executed against the view to follow the criteria set within select_statement. When a row is modified through a view, the WITH CHECK OPTION makes sure the data remains visible through the view after the modification is committed.
And you want the opposite - you want to allow data modifications performed through the view to create rows which are invisible through the view.
Create table Goods1 with "insert trigger" on it which make insert into Goods and delete from Goods1
As far as I know this isn't possible. The whole point of a view is that it is a view to a table or grouping of tables, ie. it must show the data that matches the view.
http://www.w3schools.com/sql/sql_view.asp
What you could do is create another table called GoodsView and add a trigger to it to INSERT into Goods table and DELETE from GoodsView afterwards.
http://publib.boulder.ibm.com/infocenter/iseries/v5r3/index.jsp?topic=%2Fsqlp%2Frbafysqltrig.htm
We've got a view that's defined like this
CREATE VIEW aView as
SELECT * from aTable Where <bunch of conditions>;
The "value" of the view is in the where-condition, so it is okay to use a Select * in this case.
When a new column is added to the underlying table, we have to redefine the view with a
CREATE OR REPLACE FORCE VIEW aView as
SELECT * from aTable Where <bunch of conditions>;
as the Select * seems to get "translated" into all the columns present at the time the view is (re-)defined.
My question: How can we avoid this extra step?
(If the answer is dependent on the RDBMS, we're using Oracle.)
I know you specified Oracle, but the behavior is the same in SQL Server.
One way to update the view with the new column is to use:
exec sp_refreshview MyViewName
go
Of course, I also agree with the other comments about not using a SELECT * in a view definition.
This extra step is mandatory in Oracle: you will have to recompile your view manually.
As you have noticed, the "*" is lost once you create a view:
SQL> create table t (id number);
Table created
SQL> create view v as select * from t;
View created
SQL> select text from user_views where view_name = 'V';
TEXT
-------------------------------------------------------
select "ID" from t
You should not be using * in your views. Specify the columns explicitly.
That way you are only retrieving the data you need, and thus avoid potential issues down the road where someone adds a column to a table that you do not want that view to return (e.g., a large binary column that would adversely impact performance).
Yes, you need to recompile the view to add another column, but this is the correct process. That way you avoid other compilation issues, such as if the view reference two tables, and someone adds a duplicate column name in one of the tables. The compiler would then have issues determining which of the columns was being referred to if you did not prefix a reference to the column with a table alias, or it might complain if there are duplicate column names in the results.
The problem with automatically updating views to add columns comes when you extend your model, for example to
SELECT a.*, std_name_format(a.first_name, a.middle_names, a.last_name) long_name
or even
SELECT a.*, b.* from table_a a join table_b b....
If you have a view of just SELECT * FROM table, then you probably should be using a synonym or addressing the table directly.
If the view is hiding rows (SELECT * FROM table WHERE...), then you can look at the feature variously known as Fine Grained Access Control (FGAC), Row Level Security (RLS) or Virtual Private Database (VPD).
You might be able to do something with a DDL trigger but that would get complicated.