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DEVELOPING COLDFUSION 9 APPLICATIONS
Accessing and Using Data
You can combine multiple conditions using the WHERE clause. For example, the following example uses two
conditions:
SELECT * FROM employees WHERE DeptID=3 AND Title='Engineer'
Sorting results
By default, a database does not sort the records returned from a SQL query. In fact, you cannot guarantee that the
records returned from the same query are returned in the same order each time you run the query.
However, if you require records in a specific order, you can write your SQL statement to sort the records returned from
the database. To do so, you include an ORDER BY clause in the SQL statement.
For example, the following SQL statement returns the records of the table ordered by the LastName column:
SELECT * FROM employees ORDER BY LastName
You can combine multiple fields in the ORDER BY clause to perform additional sorting:
SELECT * FROM employees ORDER BY DepartmentID, LastName
This statement returns row ordered by department, then by last name within the department.
Returning a subset of columns
You want only a subset of columns returned from a database table, as in the following example, which returns only the
FirstName, LastName, and Phone columns. This example is useful if you are building a web page that shows the phone
numbers for all employees.
SELECT FirstName, LastName, Phone FROM employees
However, this query does not to return the table rows in alphabetical order. You can include an ORDER clause in the
SQL, as follows:
SELECT the FirstName, LastName, Phone
FROM employees
ORDER BY LastName, FirstName
Using column aliases
You have column names that you do not want to retain in the results of your SQL statement. For example, your
database is set up with a column that uses a reserved word in ColdFusion, such as EQ. In this case, you can rename the
column as part of the query, as follows:
SELECT EmpID, LastName, EQ as MyEQ FROM employees
The results returned by this query contains columns named EmpID, LastName, and MyEQ.
Accessing multiple tables
In a database, you can have multiple tables containing related information. You can extract information from multiple
tables as part of a query. In this case, you specify multiple table names in the SELECT statement, as follows:
SELECT LastName, FirstName, Street, City, State, Zip
FROM employees, addresses
WHERE employees.EmpID = addresses.EmpID
ORDER BY LastName, FirstName
This SELECT statement uses the EmpID field to connect the two tables. This query prefixes the EmpID column with
the table name. This is necessary because each table has a column named EmpID. Prefix a column name with its table
name if the column name appears in multiple tables.
Last updated 8/5/2010
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