B Supported SQL Syntax and Functions

This appendix contains the following sections:

Supported SQL Statements
Oracle Functions

See Also:

Oracle Database SQL Reference for detailed descriptions of keywords, parameters, and options and the IMS documentation for details of executing SQL statements in a transaction.

B.1 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, for ALTER, CREATE, DROP, and GRANT statements, use the pass-through feature of the gateway if you need to use DDL statements against the IMS database.

Note:

TRUNCATE cannot be used in a pass-through statement.

B.1.1 DELETE

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

See Also:

"Functions Supported by IMS" for a list of supported functions.

B.1.2 INSERT

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

See Also:

"Functions Supported by IMS" for a list of supported functions.

B.1.3 SELECT

The SELECT statement is fully supported, with these exceptions:

CONNECT BY condition
NOWAIT
START WITH condition
WHERE CURRENT OF

B.1.4 UPDATE

The UPDATE statement is fully supported. However, only Oracle functions supported by IMS 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 IMS" for a list of supported functions.

B.2 Oracle Functions

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

B.2.1 Functions Not Supported by IMS

Oracle SQL functions with no equivalent function in IMS 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

See Also:

Oracle Database Error Messages for more information on error messages.

B.2.2 Functions Supported by IMS

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

Arithmetic Operators
Comparison Operators
Group Functions
String Functions
Other Functions

B.2.2.1 Arithmetic Operators

The following table specifies the arithmetic operators.

Oracle	IMS
+	+
-	-
*	*
/	/

B.2.2.2 Comparison Operators

The following table specifies the comparison operators.

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

B.2.2.3 Group Functions

The following table specifies the group functions.

Oracle	IMS
AVG	AVG
COUNT	COUNT
MAX	MAX
MIN	MIN
SUM	SUM

B.2.2.4 String Functions

The following table specifies the string functions.

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

B.2.2.5 Other Functions

The following table specifies other functions.

Oracle	IMS
ABS	ABS
CEIL	CEILING
COS	COS
EXP	EXP
FLOOR	FLOOR
LN	LOG
LOG	LOG10
MOD	%
NVL	IS NULL
POWER	POWER
ROUND	ROUND
SIN	SIN
SQRT	SQRT
TAN	TAN