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Oracle® Transparent Gateway for Microsoft SQL Server Administrator's Guide
10g Release 1 (10.1) for Microsoft Windows

Part Number B10544-01
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B
Supported SQL Syntax and Functions

This appendix contains the following sections:

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 Microsoft SQL Server database.


Note:

TRUNCATE cannot be used in a pass-through statement.


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 Microsoft SQL Server can be used.

See Also:

"Functions Supported by Microsoft SQL Server" for a list of supported functions.

INSERT

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

See Also:

"Functions Supported by Microsoft SQL Server" for a list of supported functions.

SELECT

The SELECT statement is fully supported, with these exceptions:

UPDATE

The UPDATE statement is fully supported. However, only Oracle functions supported by Microsoft SQL Server can be used.

See Also:

"Functions Supported by Microsoft SQL Server" for a list of supported functions.

Oracle Functions

All functions are evaluated by the Microsoft SQL Server database after the gateway has converted them to Microsoft SQL Server SQL equivalents. The exception is the TO_DATE function, which is evaluated by the gateway.

Functions Not Supported by Microsoft SQL Server

Oracle SQL functions with no equivalent function in Microsoft SQL Server 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 Microsoft SQL Server

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

Arithmetic Operators

Oracle Microsoft SQL Server

+

+

-

-

*

*

/

/

Comparison Operators

Oracle Microsoft SQL Server

=

=

>

>

<

<

>=

>=

<=

<=

<>, !=, ^=

<>

IS NOT NULL

IS NOT NULL

IS NULL

IS NULL

Pattern Matching

Oracle Microsoft SQL Server

LIKE

LIKE

NOT LIKE

NOT LIKE

Group Functions

Oracle Microsoft SQL Server

AVG

AVG

COUNT

COUNT

MAX

MAX

MIN

MIN

SUM

SUM

String Functions

Oracle Microsoft SQL Server

||, CONCAT

+ (expression1 + expression2)

ASCII

ASCII

CHR

CHAR

INSTR (with two arguments)

CHARINDEX

LENGTH

DATALENGTH

LOWER

LOWER

LTRIM

LTRIM

RTRIM

RTRIM

SUBSTR (second argument cannot be a negative number)

SUBSTRING

UPPER

UPPER

Other Functions

Oracle Microsoft SQL Server

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

Functions Supported by the Gateway

If an Oracle function has no equivalent function in Microsoft SQL Server, the Oracle function is not translated into the SQL statement and must be post-processed if the SQL statement is a SELECT.

The gateway, however, does support the TO_DATE function equivalent in Microsoft SQL Server, as follows:

TO_DATE(date_string | date_column)

where:

date_string is converted to a string with the following format:

yyyy-mm-dd hh:mi:ss.fff


Recommendation:

Supply the date string with the same format as the result (that is, yyyyy-mm-dd hh:mi:ss.fff).


date_column is a column with a date data type. It is converted to a parameter with a timestamp data type.


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