SQL Reference

SQL Identifiers

There are two types of SQL identifiers: ordinary identifiers and delimited identifiers.

• An ordinary identifier is a letter followed by zero or more characters, each of which is an uppercase letter, a digit, or the underscore character. An ordinary identifier should not be identical to a reserved word (see Appendix G. Reserved Schema Names and Reserved Words for information on reserved words).

• A delimited identifier is a sequence of one or more characters enclosed within quotation marks ("). Two consecutive quotation marks are used to represent one quotation mark within the delimited identifier. In this way an identifier can include lowercase letters.

Example: 

    WKLYSAL    WKLY_SAL    "WKLY_SAL"    "WKLY SAL"    "UNION"    "wkly_sal"

SQL identifiers are also classified according to their maximum length. A long identifier has a maximum length of 18 bytes. A short identifier has a maximum length of 8 bytes. These limits do not include the quotation marks surrounding the delimited identifier.

Character conversions between identifiers created on a double-byte code page but used by an application or database on a multi-byte code page may require special consideration. After conversion to multi-byte, it is possible that such identifiers may exceed the length limit for an identifier (see Appendix O. Japanese and Traditional-Chinese EUC Considerations for details).

Host Identifiers

A host identifier is a name declared in the host program. The rules for forming a host identifier are the rules of the host language. A host identifier should not be greater than 30 characters and should not begin with 'SQL'.

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