Structure of expressions (ADP)

Microsoft Office Access 2003

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An expression consists of any combination of column names, literals, operators, or functions. Follow these guidelines in combining elements to form expressions:

  • Reference columns by typing their names. If your query uses more than one table and if you use a column name that is not unique, you must add the table name and a period to the column name. The following example shows the column name job_id qualified with the table name employee: 
    employee.job_id
  • Include literal text by enclosing it in single quotation marks; no quotation marks are necessary for numbers.

    Note   The Query Designer can accept terms in double quotation marks, but might interpret them differently than you expect. In a Microsoft Access Project, the Query Designer always interprets double quotation marks as database object delimiters.

  • Use standard arithmetic operators for numbers and a concatenation operator for combining strings.
  • Include parentheses to establish precedence of operators.
  • If you include a function, use these same guidelines for the arguments passed to the function. That is, reference columns by typing their names, enclose literal text in single quotation marks, and so on.
  • If you pass column names as function arguments, be sure the data type of the column is appropriate for the function argument.
  • You can include user-defined functions returning a scalar value in an expression.

ShowExpression examples

The following table illustrates the use of expressions in a query.

Expression Result
SELECT (price * .9)
FROM products 		Displays a discounted price (10% off the value in the price column).
SELECT (lname + ', ' + fname)
FROM employee 		Displays the concatenated values of the last name and first name columns with a comma between them.
SELECT sales.qty, titles.price

FROM sales INNER JOIN titles ON
sales.title_id = titles.title_id
ORDER BY
(sales.qty * titles.price)

 After joining two tables, sorts the result set by the total value of an order (quantity times price).
SELECT au_lname, au_fname
FROM authors
WHERE
(SUBSTRING(phone, 1, 3) = '415') 		Displays authors whose area code is in the San Francisco area.
SELECT ord_num, ord_date
FROM sales
WHERE
(ord_date >=
DATEADD(day, -10, GETDATE())) 		Finds all orders in the sales table that were made in the last 10 days. Today’s date is returned by the GETDATE( ) function.
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