I have created an MS Access database and assigned a DSN to it. I want to access it through my Java application. This is what I am doing: I am getting the exception at the first line of try block. That is class.forname(“..”);. Why am I having this Exception?
Although there isn’t a syntax, you can still get close by using the built-in block comment buttons: If you’re not viewing the Edit toolbar already, right-click on the toolbar and enable the Edit toolbar: Then, select a block of code and hit the “Comment Block” button; or if it’s already commented out, use the “Uncomment … Read more
SUM is an aggregate function. It will calculate the total for each group. + is used for calculating two or more columns in a row. Consider this example, will result will result will result
Make sure you have your VendorID set as the same datatype in both the tables. N.B: Even if it is stored as a number, make sure they are both long integers. The duplicates shouldn’t prevent you from creating a relationship: duplicates restrict only when you try and create a relationship with referential integrity.
The criteria expression is the part of the query containing the conditions, as in WHERE <condition>. Look at those specifically. The error message means you’re comparing two things (this equals that, or this less than that, etc.) that are of two different, and incompatible types (comparing a number to a string, for example). You can find … Read more
I think the main reason is for data integrity. If you have a relationship between two tables invoice and invoice_item. You won’t be able to add an invoice item that does not related to an invoice. This is what you want! It’s called referential integrity. It can get pretty messy in your database if you don’t have … Read more