Sun Microsystems 5800 manual Reserved Words, Supported Expression Types

Supported Expression Types

■The following JDBC function escapes supported:

TIMESTAMPDIFF, TIMESTAMPADD, CURRENT_TIMESTAMP, CURRENT_TIME, CURRENT_DATE, HOUR, MINUTE, SECOND.

Reserved Words

Some SQL reserved words (such as BETWEEN or LIKE) are allowed in queries and are expected to occur. An SQL reserved word cannot be used as an attribute name unless it is enclosed in double quotes (for example, "FIRST"). Some other SQL reserved words (such as SELECT or CREATE) are forbidden from occurring unquoted in queries. Any query containing these words unquoted will immediately return an error. These forbidden words can be used as attribute names by enclosing them in double quotes.

Supported Expression Types

The following expression types are explicitly supported in this release of the 5800 system:

■Make use of JDBC escape syntax wherever possible. The escape syntax makes the query syntax more portable without losing functionality.

■Comparison operations: expr1 OP expr2, where OP is one of =, !=, <>, <=, >=, <, or >.

The comparison operations can compare any two expressions (for example, two attribute values or one attribute value and one literal value). The two values must be of compatible types. For example, a < comparison cannot be used between a numeric literal value and a string-valued attribute. Note that <> and != are synonyms.

■The concatenation operator, expr1 expr2.

The concatenation operator is an SQL standard way of concatenating two expressions to produce a combined output string.

■Use of parentheses to indicate precedence of evaluation.

■Boolean operators AND, OR, and NOT.

■expr1 [NOT] LIKE expr2.

–Attempts to match a character expression to a character pattern, which is a character string that includes one or more wildcards.

–% matches any number (zero or more) of characters in the corresponding position in expr1.

–_ matches one character in the corresponding position in expr1.

–Any other character matches only that character in the corresponding position in the character expression.

■expr1 BETWEEN expr2 AND expr3

Chapter 4 • Sun StorageTek 5800 System Query Language 121