Forcing a datatype in MS Access make table query

I have a query in MS Access which creates a table from two subqueries. For two of the columns being created, I'm di开发者_如何转开发viding one column from the first subquery into a column from the second subquery.

The datatype of the first column is a double; the datatype of the second column is decimal, with scale of 2, but I want the second column to be a double as well.

Is there a way to force the datatype when creating a table through a standard make-table Access query?

One way to do it is to explicitly create the table before putting anything into it.

Your current statement is probably like this:

SELECT Persons.LastName,Orders.OrderNo
INTO Persons_Order_Backup
FROM Persons
INNER JOIN Orders
ON Persons.P_Id=Orders.P_Id
WHERE FirstName = 'Alistair'

But you can also do this:

----Create NewTable
CREATE TABLE NewTable(FirstName VARCHAR(100), LastName VARCHAR(100), Total DOUBLE)
----INSERT INTO NewTableusing SELECT
INSERT INTO NewTable(FirstName, LastName, Total)
SELECT FirstName, LastName, 
FROM Person p
INNER JOIN Orders o
ON p.P_Id = o.P_Id
WHERE p.FirstName = 'Alistair'

This way you have total control over the column types. You can always drop the table later if you need to recreate it.

You can use the cast to FLOAT function CDBL() but, somewhat bizarrely, the Access Database Engine cannot handle the NULL value, so you must handle this yourself e.g.

SELECT first_column, 
       IIF(second_column IS NULL, NULL, CDBL(second_column)) 
          AS second_column_as_float
  INTO Table666
  FROM MyTest;

...but you're going to need to ALTER TABLE to add your keys, constraints, etc. Better to simply CREATE TABLE first then use INSERT INTO..SELECT to populate it.

You can use CDbl around the columns.

An easy way to do this is to create an empty table with the correct field types and then to an Append-To query and Access will automatically convert the data to the destination field.

I had a similar situation, but I had a make-table query creating a field with NUMERIC datatype that I wanted to be short text.

What I did (and I got the idea from Stack) is to create the table with the field in question as Short Text, and at the same time build a delete query to scrub the records. I think it's funny that a DELETE query in access doesn't delete the table, just the records in it - I guess you have to use a DROP TABLE function for that, to purge a table...

Then, I converted my make-table query to an APPEND query, which I'd never done before... and I just added the running of the DELETE query to my process.

Thank you, Stack Overflow !

Steve

I add a '& ""' to the field I want to make sure are stored as text, and a ' *1 ' (as in multiplying the amount by 1) to the fields I want to store as numeric.

Seems to do the trick.

To get an Access query to create a table with three numeric output fields from input numeric fields, (it kept wanting to make the output fields text fields), had to combine several of the above suggestions. Pre-establish an empty output table with pre-defined output fields as integer, double and double. In the append query itself, multiply the numeric fields by one. It worked. Finally.