Be sure to prepare one or more primary key items in the model. "Primary key" is a value that uniquely identifies data, it is a value without duplication.
Click the "details" button on the right side of the item used as the primary key.
When "Use as primary key" is checked, this item becomes the primary key. Furthermore, if "Use Sequence" is checked in the "Details of Primary Key" column, a unique number will be automatically assigned from the start number.
Click the "OK" button provided at the bottom of this window (window) and close it.
Primary key The key icon is displayed in the model item list for the item specified.
A single item that can uniquely identify data is called a "single key".
When an integer type item is specified as the primary key, the system side can assign serial numbers so that the primary key and value of existing data do not overlap when newly registering data.This is called "artificial key (or proxy key)".
The primary key that takes advantage of the characteristics of data is called "natural key".In terms of business characteristics such as employee number and product number, non-overlapping values are used as the primary key.
Those that can uniquely identify data by combining multiple items are called "compound keys". There are ways to combine multiple natural keys, or to combine natural keys and artificial keys.
Even when an artificial key (proxy key) is applied to the primary key,Missing numberMay occur.Specifically, it is the case as follows.
Some databases increase the numbering performance by keeping some order in memory beforehand, but you may erase the number held in memory.as a resultSkip number.
When using a compound key, the Web form generated by Wagby handles data in the following format.
Value of primary key 1 $ SEP $ value of primary key 2 $ SEP $ ...
That is, "$ SEP $" is the delimiter character.