| Oracle® Transparent Gateway for Microsoft SQL Server Administrator's Guide 10g Release 2 (10.2) for Microsoft Windows (32-bit) Part Number B14270-01 |
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View PDF |
| Oracle® Transparent Gateway for Microsoft SQL Server Administrator's Guide 10g Release 2 (10.2) for Microsoft Windows (32-bit) Part Number B14270-01 |
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|
View PDF |
This appendix contains the following sections:
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.
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Note: TRUNCATE cannot be used in a pass-through statement. |
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See Also: Oracle Database SQL Reference for a detailed descriptions of keywords, parameters, and options. |
The DELETE statement is fully supported. However, only Oracle functions supported by Microsoft SQL Server can be used.
The INSERT statement is fully supported. However, only Oracle functions supported by Microsoft SQL Server can be used.
The SELECT statement is fully supported, with these exceptions:
CONNECT BY condition
NOWAIT
START WITH condition
WHERE CURRENT OF
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.
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
The gateway translates the following Oracle database server functions in SQL statements to their equivalent Microsoft SQL Server functions:
| Oracle | Microsoft SQL Server |
|---|---|
| = |
= |
| > | > |
| < |
< |
| >= | >= |
| <= |
<= |
| <>, !=, ^= | <> |
| IS NOT NULL | IS NOT NULL |
| IS NULL | IS NULL |
| 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 |
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
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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.
