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Chapter 19: Introduction to Databases and SQL
Reading data from a database
You use the SQL SELECT statement to read data from a database. The SQL statement has the
following general syntax:
SELECT
column_names
FROM
table_names
[ WHERE
search_condition
]
[ GROUP BY
group_expression
] [HAVING
condition
]
[ ORDER BY
order_condition
[ ASC | DESC ] ]
The statements in square brackets are optional.
Note:
There are additional options to SELECT depending on your database. For a complete syntax
description for SELECT, see the product documentation.
This section describes options to the SELECT statement.
Results of a SELECT statement
When the database processes a SELECT statement, it returns a
record set
containing the requested
data. The format of a record set is a table with rows and columns. For example, if you write the
following query:
SELECT * FROM employees WHERE DeptID=3
The query returns the following table:
Since the data returned to ColdFusion MX by a SELECT statement is in the form of a database
table, ColdFusion MX lets you write a SQL query on the returned results. This functionality is
called
query of queries
. For more information on query of queries, see
Chapter 20, “Accessing and
Retrieving Data,” on page 427
.
The next example uses a SELECT statement to return only a specific set of columns from a table:
SELECT LastName, FirstName FROM employees WHERE DeptID=3
The query returns the following table:
Содержание ColdFusion MX
Страница 1: ...Developing ColdFusion MX Applications...
Страница 22: ...22 Contents...
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Страница 52: ...52 Chapter 2 Elements of CFML...
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Страница 218: ...218 Chapter 10 Writing and Calling User Defined Functions...
Страница 250: ...250 Chapter 11 Building and Using ColdFusion Components...
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Страница 314: ...314 Chapter 14 Handling Errors...
Страница 344: ...344 Chapter 15 Using Persistent Data and Locking...
Страница 349: ...About user security 349...
Страница 357: ...Security scenarios 357...
Страница 370: ...370 Chapter 16 Securing Applications...
Страница 388: ...388 Chapter 17 Developing Globalized Applications...
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Страница 426: ...426 Chapter 19 Introduction to Databases and SQL...
Страница 476: ...476 Chapter 22 Using Query of Queries...
Страница 534: ...534 Chapter 24 Building a Search Interface...
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