Oracle9i SQL Reference Release 1 (9.0.1) Part Number A9012501 

Basic Elements of Oracle SQL, 3 of 10
The terms literal and constant value are synonymous and refer to a fixed data value. For example, 'JACK', 'BLUE ISLAND', and '101' are all character literals; 5001 is a numeric literal. Character literals are enclosed in single quotation marks, which enable Oracle to distinguish them from schema object names.
This section contains these topics:
Many SQL statements and functions require you to specify character and numeric literal values. You can also specify literals as part of expressions and conditions. You can specify character literals with the 'text
' notation, national character literals with the N'text'
notation, and numeric literals with the integer
or number
notation, depending on the context of the literal. The syntactic forms of these notations appear in the sections that follow.
To specify a datetime or interval datatype as a literal, you must take into account any optional precisions included in the datatypes. Examples of specifying datetime and interval datatypes as literals are provided in the relevant sections of "Datatypes".
Text specifies a text or character literal. You must use this notation to specify values whenever 'text'
or char
appear in expressions, conditions, SQL functions, and SQL statements in other parts of this reference.
The syntax of text is as follows:
text::=
text
where
N
specifies representation of the literal using the national character set. Text entered using this notation is translated into the national character set by Oracle when used.
c
is any member of the user's character set, except a single quotation mark (').
A text literal must be enclosed in single quotation marks. This reference uses the terms text literal and character literal interchangeably.
Text literals have properties of both the CHAR
and VARCHAR2
datatypes:
CHAR
by comparing them using blankpadded comparison semantics.
Here are some valid text literals:
'Hello' 'ORACLE.dbs' 'Jackie''s raincoat' '09MAR98' N'nchar literal'
See Also:

You must use the integer notation to specify an integer whenever integer
appears in expressions, conditions, SQL functions, and SQL statements described in other parts of this reference.
The syntax of integer
is as follows:
integer::=
integer
where digit
is one of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.
An integer can store a maximum of 38 digits of precision.
Here are some valid integers:
7 +255
You must use the number notation to specify values whenever number
appears in expressions, conditions, SQL functions, and SQL statements in other parts of this reference.
The syntax of number
is as follows:
number::=
number
where
digit
is one of 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9.
A number
can store a maximum of 38 digits of precision.
If you have established a decimal character other than a period (.) with the initialization parameter NLS_NUMERIC_CHARACTERS
, you must specify numeric literals with 'text'
notation. In such cases, Oracle automatically converts the text literal to a numeric value.
For example, if the NLS_NUMERIC_CHARACTERS
parameter specifies a decimal character of comma, specify the number 5.123 as follows:
'5,123'
Here are some valid representations of number
:
25 +6.34 0.5 25e03 1
An interval literal specifies a period of time. You can specify these differences in terms of years and months, or in terms of days, hours, minutes, and seconds. Oracle supports two types of interval literals, YEAR
TO
MONTH
and DAY
TO
SECOND
. Each type contains a leading field and may contain a trailing field. The leading field defines the basic unit of date or time being measured. The trailing field defines the smallest increment of the basic unit being considered. For example, a YEAR
TO
MONTH
interval considers an interval of years to the nearest month. A DAY
TO
MINUTE
interval considers an interval of days to the nearest minute.
If you have date data in numeric form, you can use the NUMTOYMINTERVAL
or NUMTODSINTERVAL
conversion function to convert the numeric data into interval literals.
Interval literals are used primarily with analytic functions.
Specify YEAR
TO
MONTH
interval literals using the following syntax:
interval_year_to_month::=
interval_year_to_month
where
'integer [integer]'
specifies integer values for the leading and optional trailing field of the literal. If the leading field is YEAR
and the trailing field is MONTH
, the range of integer values for the month field is 0 to 11.
precision
is the maximum number of digits in the leading field. The valid range of the leading field precision is 0 to 9 and its default value is 2.
The leading field must be more significant than the trailing field. For example, INTERVAL
'01
' MONTH
TO
YEAR
is not valid.
The following INTERVAL
YEAR
TO
MONTH
literal indicates an interval of 123 years, 2 months:
INTERVAL '1232' YEAR(3) TO MONTH
Examples of the other forms of the literal follow, including some abbreviated versions:
You can add or subtract one INTERVAL
YEAR
TO
MONTH
literal to or from another to yield another INTERVAL
YEAR
TO
MONTH
literal. For example:
INTERVAL '53' YEAR TO MONTH + INTERVAL'20' MONTH = INTERVAL '611' YEAR TO MONTH
Specify DAY
TO
SECOND
interval literals using the following syntax:
interval_day_to_second::=
interval_day_to_second
where
integer
specifies the number of days. If this value contains more digits than the number specified by the leading precision, Oracle returns an error.
time_expr
specifies a time in the format HH[:MI[:SS[.n]]]or MI[:SS[.n]] or SS[.n], where n
specifies the fractional part of a second. If n
contains more digits than the number specified by fractional_seconds_precision
, then n
is rounded to the number of digits specified by the fractional_seconds_precision
value. You can specify time_expr
following an integer and a space only if the leading field is DAY
.
leading_precision
is the number of digits in the leading field. Accepted values are 0 to 9. The default is 2.
fractional_seconds_precision
is the number of digits in the fractional part of the SECOND
datetime field. Accepted values are 1 to 9. The default is 6.
The leading field must be more significant than the trailing field. For example, INTERVAL
MINUTE
TO
DAY
is not valid. As a result of this restriction, if SECOND
is the leading field, the interval literal cannot have any trailing field.
The valid range of values for the trailing field are as follows:

0 to 23 

0 to 59 

0 to 59.999999999 
Examples of the various forms of INTERVAL
DAY
TO
SECOND
literals follow, including some abbreviated versions:
You can add or subtract one DAY
TO
SECOND
interval literal from another DAY
TO
SECOND
literal. For example.
INTERVAL'20' DAY  INTERVAL'240' HOUR = INTERVAL'100' DAY TO SECOND

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