|
COLUMN column_name
[[[environment_name.]database_name.]table_name.]column_name[(start,
length)]
column_name represents a non-ambiguous column or portion
of a column.
column_name MUST BEGIN WITH A LETTER,
A-Z (case insensitive) and may contain up to 32 characters
including letters, numbers and allowed
special characters.
If column_name contains any reserved words or allowed
special characters, it must be enclosed in single or double
quotes.
 start
is the starting byte within column relative to one.
length
is the number of characters after the starting byte to include.
INTERNAL
The INTERNAL section is Required, however the keyword INTERNAL
is optional. It is a section identifier for the INTERNAL section
of the COLUMN definition. INTERNAL refers to the actual data
as it is stored in the DBMS.
Use of the keyword when also using an Omnidex section improves
the readability of the Environment Catalog source code.
DATATYPE datatype_spec
 Required.
Declares the data type format of the defined column. The DATATYPE
keyword is required.
LENGTH n
Required. Declares the storage length (as n) of the column
in bytes.
 C
String data is terminated by a null character. Therefore,
length must be increased by 1 to accomodate the null character.
For example, a two character State field defined as a C String
will have a length of 3: two for the abbreviated state and
one for the null character.
SCALE n
Optional. Sets the magnitude of numeric values. OmniAccess
does not format data based on SCALE. SCALE is reported in
the Environment file and the System Catalog. SCALE is used
by the Omnidex ODBC and JDBC drivers as well as for meta-data
purposes.
PRECISION n
Optional. Specifies the number of decimal places in numeric
values. OmniAccess does not format data based on PRECISION.
PRECISION is reported in the Environment file and the System
Catalog. PRECISION is used by the Omnidex ODBC and JDBC drivers
as well as for meta-data purposes.
FORMAT format_spec
Optional.
Applies to Omnidex date class data types only. Refers to the
granularity of the date data stored in the database. NOTE:
This setting DOES NOT affect the appearance of returned data.
PHYSICAL "native_column_name”
Optional. This is a quoted string of up to 255 characters
that maps the logical column name to the native column's name.
This refers to native columns. Expressions and functions are
not allowed.
USAGE usage_spec
Optional.
CENTURY THRESHOLD n
Optional. Specifies the year cutoff for determining the
century in 2 digit years. For example, if the century threshold
is set to 60, a 2 digit year of 45 would be translated to
2045 and a 2 digit year of 61 would be translated to 1961.
This setting over-rides the century threshold setting in the
environment section.
top
OMNIDEX
Optional. The OMNIDEX section is used to index data in a
format other than its native format. The keyword OMNIDEX is
a section identifier for the OMNIDEX section of the COLUMN
statement and is required if an OMNIDEX section is declared.
Definitions in this section apply to the Omnidex indexes only.
DATATYPE datatype_spec
Optional.
Declares the data type format of the defined column. The DATATYPE
keyword is required.
LENGTH n
Required. Declares the storage length (as n) of the column
in bytes.
C
String data is terminated by a null character. Therefore,
length must be increased by 1 to accomodate the null character.
For example, a two character State field defined as a C String
will have a length of 3: two for the abbreviated state and
one for the null character.
SCALE n
Optional. Sets the magnitude of numeric values. OmniAccess
does not format data based on SCALE. SCALE is reported in
the Environment file and the System Catalog. SCALE is used
by the Omnidex ODBC and JDBC drivers as well as for meta-data
purposes.
PRECISION n
Optional. Specifies the number of decimal places in numeric
values. OmniAccess does not format data based on PRECISION.
PRECISION is reported in the Environment file and the System
Catalog. PRECISION is used by the Omnidex ODBC and JDBC drivers
as well as for meta-data purposes.
FORMAT format_spec
Optional.
Applies to date class data types only. Refers to the granularity
of the date data stored in the index files. NOTE:
This setting DOES NOT affect the appearance of returned data.
top
AS select_item
Optional. Generates Pseudo-columns using SQL standard expressions
and functions, with limitations. Pseudo-columns allows columns
to be included in the environment file that do not exist in
the native database. select_item can be an expression or function.
The pseudo-column is read/write.
SQL SELECT "string"
Optional. Generates Pseudo-columns using native database
functions and expressions. Values are read-only.
Unless
the column data can only be generated through native database
functions that are not supported by Omnidex, DISC highly recommends
that the AS select_item (above) clause be used instead of
the SQL SELECT string clause.
String clauses support any of the following tokens that represent
the current DATABASE, TABLE or COLUMN.
To pass double quotes ( " ) in a rule to the native
database, enclose the string in single quotes ( ' ). The converse
is true for single quotes. Mixing double quotes and single
quotes within strings is not supported. The following illustrates
a few valid examples:
SQL
SELECT "to_char(%t.%c)"
SQL
SELECT "%t.%c + %t.AMOUNT"
SQL
SELECT "%t.%c * 1.0725"
PROMPT "string"
Optional. This is a string of up to 32 characters used when
setting a prompt for a value for the field. Prompt is for
meta-data purposes only. It is not used by Omnidex in any
way but is included as meta-data with some info calls.
HEADING "string"
Optional. This is a string of up to 32 characters used when
setting a heading or name for a field appearing above the
column being reported. Heading is for meta-data purposes only.
It is not used by Omnidex in any way but is included as meta-data
with some info calls.
LABEL "string"
Optional. This is a string of up to 32 characters used when
setting a label or name for a field, appearing to the left
of the column being reported. Label is for meta-data purposes
only. It is not used by Omnidex in any way but is included
as meta-data with some info calls.
CARDINALITY n
The cardinality of a column is the number of distinct values
in the column. This number should be within 1% of actual column
cardinality. Omnidex uses this number to better optimize some
queries.
top
|
