Prepared Statement

CData Virtuality supports java.sql.PreparedStatement. Prepared statements can be very important in speeding up common statement execution, since they allow the server to skip parsing, resolving, and planning of the statement.

Known Limitations

Bind variable types in function signatures, e.g. WHERE t.name = UCASE(?) can be determined if the function has only one signature or if the function is used in a predicate where the return type can be determined. In more complex situations, it may be necessary to add a type hint with a cast or convert, e.g. UCASE(CONVERT(?, STRING))

Examples

UCASE function has two signatures, one for theSTRING data type IN parameter and another one for the CLOB data type IN parameter.

In the following cases, it can be determined:

CODE

SELECT * FROM t WHERE t.name = UCASE(?)
SELECT * FROM t WHERE UCASE(t.name) = 'AAA'
SELECT * FROM t WHERE UCASE(t.name) LIKE '%QWE%'

In this case, it cannot be determined, and CAST or CONVERT must be used:

CODE

SELECT UCASE(CONVERT(?, STRING))