Αποτελέσματα Αναζήτησης
You can prevent duplicate values in a field in an Access table by creating a unique index. A unique index is an index that requires that each value of the indexed field is unique. There are two basic ways that you can create a unique index:
An add-in lets you run code in any database without having to create or import anything. Add-ins can save time and make code more accessible. How to make and install an add-in for Microsoft Access. USysRegInfo table, add-in properties, code tips.
29 Ιουλ 2011 · I'm trying to create a unique multi-column index on a table in Access. Several of the fields I'll be using in the index are long integers. These fields may be blank in some records.
Since MS Access 2007, Microsoft has distributed the runtime versions for free. You can download them from here: Office 365, Access 2021, 2019. Office 365 and Access 2021/2019 Runtime. New Features. Microsoft Access 2016.
17 Μαρ 2022 · Syntax. CREATE [ UNIQUE ] INDEX index ON table (field [ASC|DESC] [, field [ASC|DESC], …]) [WITH { PRIMARY | DISALLOW NULL | IGNORE NULL }] The CREATE INDEX statement has these parts: The name of the index to be created.
Access automatically creates a unique index for primary keys, but you might also want to prohibit duplicate values in other fields. For example, you can create a unique index on a field that stores serial numbers so that no two products have the same serial number. Create a single-field index
Here’s an example to create a Unique index: CREATE UNIQUE INDEX Emp_Phone_IDX ON Employees (emp_phone); There are several other options to the create index statement – we have shown the common options. One powerful feature of the create index statement is to create an index on an ODBC linked table.
