Literals

Note: You cannot specify LONG and LONG RAW values in cases in which Oracle can perform implicit datatype conversion. For example, LONG and LONG RAW values cannot appear in expressions with functions or operators. For information on the limitations on LONG and LONG RAW datatypes, see "LONG Datatype" on page 2-14.

See Also: "Conversion Functions" on page 6-6 of the SQL

Reference for details on all of the explicit conversion functions

Literals

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:

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Literals

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" on page 2-2.

Text Literals

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::=

N

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 (’).

■’ ’ are two single quotation marks that begin and end text literals. To represent one single quotation mark within a literal, enter two single quotation marks.

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:

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Literals

■Within expressions and conditions, Oracle treats text literals as though they have the datatype CHAR by comparing them using blank-padded comparison semantics.

■A text literal can have a maximum length of 4000 bytes.

Here are some valid text literals:

’Hello’

’ORACLE.dbs’ ’Jackie’’s raincoat’ ’09-MAR-98’

N’nchar literal’

See Also:

■"About SQL Expressions" on page 4-2 for the syntax description of expr

■"Blank-Padded Comparison Semantics" on page 2-45

Integer Literals

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::=

+

–

digit

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

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Literals

See Also: "About SQL Expressions" on page 4-2 for the syntax description of expr

Number Literals

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::=

+

. digit

–digit

where

■+ or - indicates a positive or negative value. If you omit the sign, then a positive value is the default.

■digit is one of 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9.

■e or E indicates that the number is specified in scientific notation. The digits after the E specify the exponent. The exponent can range from -130 to 125.

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, then 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’

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