I am working on a project in ACCESS 2010 that requires me to give a rank to 30000 products based on their sales. I have tried using a query to do the ranking and it takes a long time. (Please find codes at Making the ranking query efficient)
I figured out that instead, I can just sort the table based on the Sales column and add a field with numbers 1 to 30000.
So is there a way to add such a column, i.e. a column without any relationship to the existing table.
Add a field to the actual table? If that's the case, make a table and run this query:
ALTER TABLE yourTableName
ADD COLUMN yourColumnName AUTOINCREMENT(1, 1)
Related
How to select only specific number of columns from a table in hive. For Example, If I have Table with 50 Columns, then how Can I just select first 25 columns ? Is there any easy way to do it rather than hard coading the column names.
I guess that you're asking about using the order in which you defined your columns in your CREATE TABLE statement. No, that's not possible in Hive for the moment.
You could do the trick by adding a new column COLUMN_NUMBER and use that in your WHERE statements, but in that case I would really think twice of the trade off between spending some more time typing your queries and messing your whole table design by adding unnecessary columns. Apart from the fact that if you need to change your table schema in the future (for instance, by adding a new column), adapting your previous code with different column numbers would be painful.
I am working on an MS Access 2013 database. I have two tables:
Customers (28 records)
Chemicals (34 records)
I need to create a table for usage rates for each customer for each chemical.
The rates will be entered manually (at user's request). I am trying to determine how to create a new table where the customer-chemical fields will combine to be primary key.
The resulting table should have 28x34=952 unique records.
The goal is to then have a form wherein the user can select the customer, then the chemical, and edit the rate.
For any table/query creation I am comfortable using either the Access interface or SQL.
I will advise to create a new table containing 4 columns. The first column will be an 'id' it is going to be your primary key (auto-increment if you want), second column is the customer, then the chemical, and finally the rating. Then if you format your query to select 'rating' where customer='customer name' and chemical='chemical name', you should get the desired result you want.
Thank you for the reply. Did a little more wrestling with it and used the following SQL to create the table:
SELECT customers.customer, chemicals.chemical
INTO UsageRates
FROM Chemicals, Customers
Then adding a blank 'rate' field to the table.
What would be the expression to create a calculated column in Table Example 2 called "SZODMAXCALC", that would contain the SZODMAXCALC from Table Example 1 given that the data from Table Example 1 falls between the dates (DTTMSTART and DTTMEND) within Table Example 2?
Maybe this is easier done on the SQL side that loads the data?
there is no way to create a calculated column that references a column in another table.
you will need to do a join either in Spotfire (via Insert...Columns)* or on the SQL-side of things (either via a view on your database or by creating a new information link in Spotfire).
the best method depends on your data structure, implementation, and desired results, so I'm not able to recommed there. take a look at both options and evaluate which one works best.
* NOTE that Spotfire cannot join based on a Calculated Column as a common key. that is, using your example, if [WELLNAME] is a calculated column, you cannot tell Spotfire the equivalent of SELECT wellname, ... FROM table_a LEFT JOIN table_b ON table_a.wellname = table_b.wellname.
the alternative is to Insert...Transformation and choose Insert New Calculated Column, and to join on that instead.
the reason for this is that calculated columns are very mutable; they could change frequently based on a user action. it would be inefficient to re-execute the join each time the column's contents changed. conversely, a "Transformation Calculated Column" is only updated when the data table is loaded.
I need your assistance to figure out how to achieve the following in MS access database.
I have a table with a lot of columns but one of them has a numeric value that will be used as how many times will the record will be repeated.
I need to make another table with repeated records based on Count column.
Build a numbers (aka tally) table (you can google it). I'll call it tblNumbers. Then all you need to do is create a query SELECT <yourTable>.* FROM <yourTable>, tblNumbers WHERE tblNumbers.Number <= <yourTable>.<numberField>
I want to change the order of column e.g. name is first column of my table and there are 10 other columns in table I want to insert a new column in 2nd position after name column.
How is this possible?
1 - It's not possible without rebuilding the table, as Martin rightly points out.
2 - It's a good practice anyways to specify what fields you want and in what order in your SELECT statements as n8wrl points out.
3 - If you really really need a fixed order on your fields, could create a view that selects the fields you want in the order you want.
Like the rows in the table, there is no meaning to the order of the columns. In fact, it is best to specify the order you want the columns in your select statements rather than using select *, so you can 'insert' new columns wherever you want just by writing your SELECT statements accordingly.
Its possible to change the order. In some instances it really matters. have a personal experience.
Anyway..this query works fine.
ALTER TABLE user MODIFY Name VARCHAR(150) AFTER address;
You can achieve this by following these steps:
remove all foreign keys and primary key of the original table.
rename the original table.
using CTAS, create the original table in the order you want.
drop the old table.
apply all constraints back to the original table.