Supported SQL Syntax and Functions

B Supported SQL Syntax and Functions

The following topics describe supported SQL Syntax and 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 Teradata database.

See Also:

Oracle Database SQL Language Reference for detailed descriptions of keywords, parameters, and options.

DELETE

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

See Also:

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

INSERT

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

See Also:

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

SELECT

The SELECT statement is fully supported, with these exceptions:

CONNECT BY condition
NOWAIT
START WITH condition
WHERE CURRENT OF

UPDATE

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

Oracle Functions

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

Functions Not Supported by Teradata

Oracle SQL functions with no equivalent function in Teradata are not supported in DELETE, INSERT, or UPDATE statements, but are evaluated by the Oracle database if the statement is a SELECT statement. That is, the Oracle database 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 Teradata

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

Arithmetic Operators

Oracle	Teradata
`+`	`+`
`-`	`-`
`*`	`*`
`/`	`/`

Comparison Operators

Oracle	Teradata
`=`	`=`
`>`	`>`
`<`	`<`
`>=`	`>=`
`<=`	`<=`
`<>`, `!=`, `^=`	`<>`, `!=`
`IS NOT NULL`	`IS NOT NULL`
`IS NULL`	`IS NULL`

Group Functions

Oracle	Teradata
`AVG`	`AVG`
`COUNT`	`COUNT`
`MAX`	`MAX`
`MIN`	`MIN`
`SUM`	`SUM`

String Functions

Oracle	Teradata
`INSTR`	`POSITION`

Other Functions

Oracle	Teradata
`ABS`	`ABS`
`EXP`	`EXP`
`LOG(a, b)`	`LOG10(b) / LOG10(a)`
`POWER`	`**`
`SQRT`	`SQRT`