I have a task to do synchronizing view with table in phpmyadmin. As example, I have a view table like this:
VIEW:
TABLE:
the data records of table is same as view. I copy the data from view to table using
CREATE TABLE tablename AS (SELECT * FROM viewname)
I want to synchronize them. As example, when view is updated then table will be updated too. The meaning of view's updating is like editing the view then I import the view again by deleting the old one. Is there any way to do that? I want to synchronize the view and the table because the time took so long when I open the view. So I made table which is same as view so that I'm able to open it faster. Thanks in advance
VIEW in MySQL is a virtual table or logical view of a table as mentioned by Jens that has no data stored on it like a table.
Instead, it fetches the values directly from the table. The values in VIEW changes when the values from the table it fetches changes.
Therefore you will need to sync between the tables and not between view and table.
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.
I created a view using the Members table. If I truncate the Members table will it automatically truncate the view data?
A view is like a virtual table and does not have a Physical existence. A View is derived from an SQL Query which may pull data from a Single table or Multiple ones.
So when you do a query on a view, What it actually does is running the View Query on the background. So if you make any changes in the data on the Tables using the Underlying script, then the same will be effected automatically in the view
I have tables in database that consist of so many data records. I made view tables because I joined the tables. Then, when I tried to open the view tables, the time took so long because the tables had many data. So, I decided to make temporary table like this:
CREATE TABLE temp_ AS (SELECT * FROM view)
then, I want to synchronize the view and temporary table. As the example, when I tried to update the view table, then we're able to know that the temporary table has to change too because the temporary is synchronized with the view table. Maybe, it can be solved when the view's updated time > generated time than we have to update the table
I have table like this
I manually inserted the data records to both of that table. What may I do to synchronize them? Thanks in advance
I am new to access database.
I created a linked table (linked to an excel file)
I them created a local table which is just a filtered table from the linked table. (same table just filtered for some records.)
The issue I am running into is that I am not able to refresh this local filtered table. The steps I am following are :
Refresh linked table using 'linked table manager'
Refresh the local table (filtered version of linked table) using linked table manager and the refresh button in the menu bar.
While my linked table gets refreshed, this filtered table does not get refreshed.
Can someone suggest what I can do?
Thanks in advance
You might want to use a query rather then your local, filtered, table.
If you want to keep your current structure try this
Create -> Query Design -> click on SQL on the bottom right -> paste the following code in
SELECT * INTO local_filtered_table
FROM linked_table
WHERE <put your conditions here>;
Then run this query each time you update your linked table.
Or you can do as Rene suggested and just make a query instead of a local table which would look something like this.
SELECT *
FROM linked_table
WHERE <put your conditions here>;
I have to create a particular system of reviews in which I should do a lot of AVG in my query, so I want to ask if it's possible to create a table in SQL in which I have these Averages automatically updated?
Mysql 5.5.24-0ubuntu0.12.04.1
Yes, there are two ways to do this:
You can create a "view", which is like a table, except that its records come from a SQL query (usually derived from other tables) rather than being stored directly. See http://dev.mysql.com/doc/refman/5.6/en/create-view.html.
You can create a "trigger", which is procedural code that runs whenever a specified table is modified in a specified way. In your case, you would create a trigger that runs whenever one table is modified, and that re-generates the secondary table. See http://dev.mysql.com/doc/refman/5.6/en/create-trigger.html.