You can use an expression (expression: Any combination of mathematical or logical operators, constants, functions, and names of fields, controls, and properties that evaluates to a single value. Expressions can perform calculations, manipulate characters, or test data.) in many places in an SQL statement (SQL string/statement: An expression that defines an SQL command, such as SELECT, UPDATE, or DELETE, and includes clauses such as WHERE and ORDER BY. SQL strings/statements are typically used in queries and in aggregate functions.), as the following examples show. Expressions are shown in bold text.
|SELECT [FirstName], [LastName] FROM [Employees] WHERE [LastName] = "Davolio";
||Displays the values in the FirstName and LastName fields for employees whose last name is Davolio.
|SELECT [ProductID], [ProductName] FROM [Products] WHERE [CategoryID] = Forms![New Products]![CategoryID];
||Displays the values in the ProductID and ProductName fields in the Products table for records in which the CategoryID value matches the CategoryID value specified in an open New Products form.
|SELECT Avg([ExtendedPrice]) AS [Average Extended Price] FROM [Order Details Extended] WHERE [ExtendedPrice] > 1000;
||Displays in a field named Average Extended Price the average extended price of orders for which the value in the ExtendedPrice field is more than 1,000.
|SELECT [CategoryID],Count([ProductID]) AS [CountOfProductID]
FROM [Products] GROUP BY [CategoryID] HAVING Count([ProductID]) > 10;
|Displays in a field named CountOfProductID the total number of products for categories with more than 10 products.