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Supported SQL Syntax and Functions

This appendix contains the following sections:.

• Supported SQL Statements

• Oracle Functions

Supported SQL Statements

With a few exceptions, the gateway provides full support for Oracle DELETE, INSERT, SELECT, and UPDATE statements.

The gateway does not support Oracle Data Definition Language (DDL) statements. No form of the Oracle ALTER, CREATE, DROP, GRANT, or TRUNCATE statements can be used. Instead, use the pass-through feature of the gateway if you need to use DDL statements against the Sybase database.

See Also: "Using the Pass-Through Feature" and Oracle8i SQL Reference for a detailed descriptions of keywords, parameters, and options.

DELETE

The DELETE statement is fully supported. However, only Oracle functions supported by Sybase can be used.

See Also: "Functions Supported by Sybase" for a list of supported functions.

INSERT

The INSERT statement is fully supported. However, only Oracle functions supported by Sybase can be used.

See Also: "Functions Supported by Sybase" for a list of supported functions.

SELECT

The SELECT statement is fully supported, with these exceptions:

• CONNECT BY condition

• FOR UPDATE

• FOR UPDATE OF

• NOWAIT

• START WITH condition

• WHERE CURRENT OF

UPDATE

The UPDATE statement is fully supported. However, only Oracle functions supported by Sybase can be used. Also, you cannot have SQL statements in the subquery that refer to the same table name in the outer query. Subqueries are not supported in the SET clause

See Also: "Functions Supported by Sybase" for a list of supported functions.

Oracle Functions

All functions are evaluated by the Sybase database after the gateway has converted them to Sybase SQL.

Functions Not Supported by Sybase

Oracle SQL functions with no equivalent function in Sybase are not supported in DELETE, INSERT, or UPDATE statements, but are evaluated by the Oracle database server if the statement is a SELECT statement. That is, the Oracle database server performs post-processing of SELECT statements sent to the gateway.

If an unsupported function is used in a DELETE, INSERT, or UPDATE statement, the following Oracle error occurs:

ORA-02070: database db_link_name does not support function in this context

Functions Supported by Sybase

The gateway translates the following Oracle database server functions in SQL statements to their equivalent Sybase functions:

• Arithmetic Operators

• Comparison Operators

• String Functions

• Group Functions

• Other Functions

Arithmetic Operators

Oracle	Sybase
+	+
-	-
*	*
/	/

Comparison Operators

Oracle	Sybase
=	=
>	>
<	<
>=	>=
<=	<=
<>, !=, ^=	<>, !=
IS NOT NULL	IS NOT NULL
IS NULL	IS NULL

String Functions

Oracle	Sybase
||	+ (expression1 + expression2)
ASCII	ASCII
CHR	CHAR
INSTR	CHARINDEX
LENGTH	CHAR_LENGTH
LOWER	LOWER
SUBSTR (second argument cannot be a negative number)	SUBSTRING
UPPER	UPPER

Group Functions

Oracle	Sybase
AVG	AVG
COUNT	COUNT
MAX	MAX
MIN	MIN
SUM	SUM

Other Functions

Oracle	Sybase
ABS	ABS
CEIL	CEILING
COS	COS
EXP	EXP
FLOOR	FLOOR
LN	LOG
LOG	LOG10
MOD	%
NOT NVL	IS NOT NULL
NVL	IS NULL
POWER	POWER
ROUND	ROUND
SIN	SIN
SQRT	SQRT
TAN	TAN