Application.DLookup (Access)

You can use the DLookup function to get the value of a particular field from a specified set of records (a domain).

You can use the DLookup function to display the value of a field that isn't in the record source for your form or report. For example, suppose you have a form based on an Order Details table. The form displays the OrderID, ProductID, UnitPrice, Quantity, and Discount fields. However, the ProductName field is in another table, the Products table. You could use the DLookup function in a calculated control to display the ProductName on the same form. The DLookup function returns a single field value based on the information specified in criteria. Although criteria is an optional argument, if you don't supply a value for criteria, the DLookup function returns a random value in the domain. If no record satisfies criteria, or if domain contains no records, the DLookup function returns a Null. If more than one field meets criteria, the DLookup function returns the first occurrence. You should specify criteria that will ensure that the field value returned by the DLookup function is unique. You may want to use a primary key value for your criteria, such as [EmployeeID] in the following example, to ensure that the DLookup function returns a unique value:

DLookup (Expr, Domain, Criteria)

Dim varX As Variant 
varX = DLookup("[LastName]", "Employees", "[EmployeeID] = 1")

Arguments

The following arguments are required:

Expr (String) - An expression that identifies the field whose value you want to return. It can be a string expression identifying a field in a table or query, or it can be an expression that performs a calculation on data in that field. In expr, you can include the name of a field in a table, a control on a form, a constant, or a function. If expr includes a function, it can be either built-in or user-defined, but not another domain aggregate or SQL aggregate function.

Domain (String) - A string expression identifying the set of records that constitutes the domain. It can be a table name or a query name for a query that does not require a parameter.

Optional arguments

The following argument is optional

Criteria (String) - An optional string expression used to restrict the range of data on which the DLookup function is performed. For example, criteria is often equivalent to the WHERE clause in an SQL expression, without the word WHERE. If criteria is omitted, the DLookup function evaluates expr against the entire domain. Any field that is included in criteria must also be a field in domain; otherwise, the DLookup function returns a Null.