Keywords and Identifiers

SQL statements are provided as strings to GemFire XD that must follow several rules.

Permitted character set is unicode
Single quotation marks delimit character strings
Within a character string, a single quotation mark itself can be represented using two single quotation marks
SQL keywords and identifiers are case-insensitive
Double quotation marks denote delimited identifiers as in the next section
In accordance with SQL-92 standard, comments can be single-line or multi-line. Single-line comments start with two dashes (--) and end with the newline character while multi-line comments start with forward slash star (/*) and end with start forward slash (*/).

Standard SQL Identifiers

Two categories of identifiers are defined in SQL-92 standard: ordinary and delimited.

The rules mentioned here for SQL identifiers apply to all names used in SQL statements including table-name, column-name, view-name, synonym-name, constraint-name, correlation-name, index-name, trigger-name, function-name and procedure-name. There are two categories of identifiers as defined in SQL-92 standard: ordinary and delimited. The ordinary names must follow the below mentioned rules:

Can contain only unicode letters and digits, or underscore characters ( _ )
Must begin with an alphabetic character
Should have a minimum length of one byte and a maximum of 128 bytes
Are case-insensitive (use delimited identifiers for case-sensitive)
Cannot contain quotation marks or spaces
Cannot be a reserved word

Delimited identifiers are those enclosed within double quotation (") marks. If the identifier itself needs to have a double quotation mark then two consecutive double quotation marks should be used.

The following conventions are used in the syntax definitions in the remaining document:

Square brackets ([]) are used to enclose optional items.
Braces ({}) are used to group items and is not part of syntax as such.
A star (*) denotes that the preceding item can be repeated 0 or more number of times.
A pipe (|) is for ORing different elements i.e. one of the ORed items are needed.
An explicit bracket, brace, star or pipe will be shown enclosed in single quotes e.g. '*' . Parentheses have no special meaning and are always literals.