Sets the designated parameter to SQL NULL.

Note: You must specify the parameter's SQL type.

Parameters:

parameterIndex		the first parameter is 1, the second is 2, ...
sqlType		the SQL type code defined in java.sql.Types

Exceptions:

SQLException		if parameterIndex does not correspond to a parameter marker in the SQL statement; if a database access error occurs or this method is called on a closed PreparedStatement
SQLFeatureNotSupportedException		if sqlType is a ARRAY, BLOB, CLOB, DATALINK, JAVA_OBJECT, NCHAR, NCLOB, NVARCHAR, LONGNVARCHAR, REF, ROWID, SQLXML or STRUCT data type and the JDBC driver does not support this data type