B
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 Ingres II database.

See Also: Oracle Database SQL Reference for a detailed descriptions of keywords, parameters, and options.

DELETE

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

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

INSERT

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

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

SELECT

The SELECT statement is fully supported, with these exceptions:

• CONNECT BY condition

• NOWAIT

• START WITH condition

UPDATE

The UPDATE statement is fully supported. However, only Oracle functions supported by Ingres II can be used. Column values can be set only to expressions; they cannot be set with subqueries.

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

Oracle Functions

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

Functions Not Supported by Ingres II

Oracle SQL functions with no equivalent function in Ingres II 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 Ingres II

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

• Arithmetic Operators

• Comparison Operators

• Group Functions

• String Functions

• Pattern Matches

• Other Functions

Arithmetic Operators

Oracle	Ingres II
+	+
-	-
*	*
/	/

Comparison Operators

Oracle	Ingres II
=	=
>	>
<	<
>=	>=
<=	<=
<>, !=, ^=	<>, !=
BETWEEN X AND Y	BETWEEN X AND Y
IS NOT NULL	IS NOT NULL
IS NULL	IS NULL
NOT BETWEEN X AND Y	NOT BETWEEN X AND Y

Group Functions

Oracle	Ingres II
AVG	AVG
COUNT	COUNT
MAX	MAX
MIN	MIN
SUM	SUM

String Functions

Oracle	Ingres II
||	+
LENGTH	LENGTH
LOWER	LOWERCASE
SUBSTR (with 2 arguments - the arguments cannot be negative numbers)	shift('string', from)
SUBSTR (with 3 arguments - the arguments cannot be negative numbers)	left(shift('string', from), for)
UPPER	UPPERCASE

Pattern Matches

Oracle	Ingres II
LIKE 'a%'	LIKE "a%", MATCHES "a*"
LIKE 'a_'	LIKE "a_", MATCHES "a?"
LIKE 'a\%' ESCAPE '\'	LIKE "a\%" ESCAPE "\"
NOT LIKE	NOT LIKE

Other Functions

Oracle	Ingres II
ABS	ABS
COS	COS
EXP	EXP
LN	LOGN
MOD	MOD
NVL	IFNULL
POSITION	LOCATE
RTRIM	TRIM
SIN	SIN
SQRT	SQRT