Field Names and Aliases

Field names are names of fields of the input records generated by an input format.

Aliases are alternative names for field-expressions, assigned in the SELECT or USING clauses. When a field-expression in the SELECT clause has been aliased, output formats will use the alias as the name of the corresponding output record field.
The alias of a field-expression can be also used anywhere else in the query as a shortcut that refers to the original field-expression.

Remarks:

• The following characters are not allowed in field names or aliases, unless the field name or alias is enclosed in square brackets ( [ and ] ):
  

  , ; < > = ! ' " @ * [ ] space

  Field names and aliases containing spaces or illegal characters can be enclosed in square brackets ( [ and ] ), as in the following example:
  

  SELECT [Last Request Time], [email@address], CPUTime as [Elapsed CPU Time]
  FROM perflog.csv
  WHERE [Elapsed CPU Time] > 0
  

• Any character (including illegal characters and non-printable characters) in field names and aliases can be also entered using the \uxxxx notation, where xxxx is the 4-digit hexadecimal representation of the UNICODE character:
  

  SELECT Last\u0020Request\u0020Time
  FROM perflog.csv
  

• Field names and aliases can not match keywords or function names of the Log Parser SQL-Like language (e.g. "FROM", "ADD").
• Field names and aliases are not case-sensitive.

Examples:

A. Basic field-expressions

The SELECT clause in the following example query specifies "basic" field-expressions only:

SELECT 'Event ID:', EventID, SYSTEM_TIMESTAMP()
FROM System

B. Derived field-expressions

The SELECT clause in the following example query specifies "derived" field-expressions only:

SELECT TO_UPPERCASE(cs-uri-stem), SUM(sc-bytes)
FROM \MyLogs\ex042805.log
GROUP BY TO_UPPERCASE(cs-uri-stem)

See also:

Basics of a Query

© 2004 Microsoft Corporation. All rights reserved.