I'd like to know if it is possible to create an SQL function that will automatically update my View and add to it new tables in my DB.
My DB consist of multiple tables (same data structure) and are named as follow "MM_DD", now I would like to create a VIEW that joins all this data ( pretty simple , see query below) but I wish to automate the process so every time a new table is added the view will update.
CREATE OR REPLACE VIEW `viewTable` AS
select *,
md5(CONCAT(`columnA`,`columnB`)) AS myPK_id
from `05_06`
union all
select *,
md5(CONCAT(`columnA`,`columnB`)) AS myPK_id
from `05_08`
ect...
What I am doing at the moment is using PHP every time a table is added. It loops through the tables and create / update the view.
select * from information_schema.tables WHERE table_name LIKE '%05%'
Now that I have an array of table names -> create my Query string -> replace view...
Is this possible to do this in SQL?
If so, what is the correct approach?
Write a stored procedure to rebuild your view. You'll need to use what MySQL internally calls "prepared statements" so you can use string manipulation.
You'll still use your SELECT ... FROM information_schema.tables query to drive this stored procedure.
Once you get this working, you can embed it in a mySQL event, and arrange to run it automatically. For example, you could run it at the same time late at night.
Or, you can invoke the stored procedure immediately after you create one of these tables.
Related
Right now, I'm altering a table with a crap ton of data, which is going to take weeks to run. In the meantime, I figured I'd create a new table to write to while this one is locked.
I can create an empty table and just write to this one, and check both tables when reading. Or I can create a copy of the current table and do all reads/writes from this copy for the next month.
It looks like copying the table is not the best solution. What about creating a view (just to read from) combining both tables?
CREATE VIEW MY_TABLE_VIEW AS
SELECT * FROM MY_TABLE
UNION ALL
SELECT * FROM MY_TABLE_COPY
Would creating the view be just as expensive as altering the original table? Should I instead just change all my table reads to UNION ALL the results from both tables?
Creating a view is a metadata-only operation. Views don't store any data. Querying the view will actually query the base table as if you ran the query in the view definition. So there's practically nothing to do to create the view. It only stores the query as metadata.
Sorry for asking this question, but I am a beginner in SQL, my colleague at work build a view, which I need as datasource for a report, however since this view is based on several other views it takes like 45 minutes to execute the query. This is way to long. Therefore I created a table from that view, initial execution time is the same, but once in place it executes in seconds.
In Microsoft SQL Server 2014 I used the following query:
select *
into [dbo].[MAT_v_demnew_daily_am_all_data]
from [dbo].[v_demnew_daily_am]
This works fine, but since the view is updated daily I also need to refresh the table everyday. When I now execute the above mentioned query I get the message that the table already exists.
That's why I tried to use 'insert' in this case:
insert into [dbo].[MAT_v_demnew_daily_am_all_data]
select *
from [dbo].[v_demnew_daily_am]
Here I have the problem that it not only inserts the additional data but also the already existing data, so in the end I have duplicates.
As a workaround I now manually delete the [dbo].MAT_v_demnew_daily_am_all_data] table and then execute the select * into query.
Now I am looking for an easier solution, is it possible to having the table deleted by query and in the same query create a new one by select * into or is it possible to only insert new data from the view to the table so that I don't get duplicates.
Moreover, is it possible to have such SQL statement being executed automatically on a daily basis, maybe by .bat file and windows task scheduler?
I know that the source of all problems is the View and that we should improve that, but looking for a short term solution first.
Thanks so much.
Mathias
Try this:
IF OBJECT_ID('dbo.MAT_v_demnew_daily_am_all_data', 'U') IS NOT NULL
DROP TABLE dbo.MAT_v_demnew_daily_am_all_data
SELECT INTO dbo.MAT_v_demnew_daily_am_all_data FROM dbo.v_demnew_daily_am
This query is reusable on a daily basis.
You can create one stored procedure including this query.
Then you only need to execute the stored procedure.
Updated
Before you create the stored procedure, please check if you have the permission.
Then try:
create procedure [procedure_name]
as
IF OBJECT_ID('dbo.MAT_v_demnew_daily_am_all_data', 'U') IS NOT NULL
DROP TABLE dbo.MAT_v_demnew_daily_am_all_data
SELECT INTO dbo.MAT_v_demnew_daily_am_all_data FROM dbo.v_demnew_daily_am;
After you create it:
EXEC [procedure_name];
How I see into MsSql sys.sysprocesses
can I modify it?
Example :
select count(spid) from master.dbo.sysprocesses
The result will be what I want
As Dan has stated, sys schema objects cannot be modified, you will get an error if you try to do so.
The sys.sysproccesses view can be queried using the statement you have posted from a query window and will return results
select count(spid) from master.dbo.sysprocesses
If you are really wanting to "modify" which I assume means you want to update values, drop rows and such, you can add to a temp table and modify that but the data is a copy so anything you do will not affect the underlying view
SELECT *
INTO #MyTable
FROM sys.sysprocesses
sysprocesses is a view and a legacy one at that. One cannot modify system objects.
You can create your own view to encapsulate DMV queries:
CREATE VIEW dbo.YourView
SELECT COUNT(session_id) AS SessionCount
FROM sys.dm_exec_sessions;
GO
I'm rather new at database management, so this might not be feasible, but I got a handful of SQL select queries, rather long ones at that. What I'd like is to get the table column names and structure, without access to the actual database, so as to get a map of all this queries.
context: All we have are the queries used to output tables that will be given to us latter.
This need not be done with actual SQL code, maybe a short script in other language or a utility somebody knows of (but I do have MySQL workbench)
You can add a CREATE TABLE statement in front of your select queries to get the column names.
You cannot infer data types or keys from select queries.
For column names do something like:
drop table if exists your_table_name;
create table your_table_name
select *
from ...
where the select * portion is replaced by the select queries you have.
Then to see the column names in a friendlier way you can do:
show create table your_table_name;
or
desc your_table_name;
I'm working on a Task where I should get the datas from all the table from the Database without knowing the table names. What I'm planning to do is to write a query to get all the table names and column names and store it in a temporary table.
Once I got the table name and column name I have to store the values to the variables like #Table_Name and #Column_Name. Then I have to call the table names within a Loop and have to write a query like this
"select * from '''+#Table_Name+''' where '''+#Column_Name+''' = 1"
Earlier I used cursor to get the values and store it in a variable and call it within the loop. But it seems that the cursor is consuming more time and memory. So I thought of changing it using temporary table.
My doubt is, is it possible to assign the Temporary table values to a variable to use it later. If possible how to do it?
Your idea may not work, I feel, since you are trying to incorporate the concept of arrays in SQL Server. SQL Server does not have arrays, but it has tables. You can obtain the data you need by creating a temporary table. Inserting into it by firing a query like
select * from sys.tables.
Then trying to do your operation by loading each row from this table. After your work is done, by all means drop the table.