Java Reference
In-Depth Information
procedure-element
is expressed as
{
| [ DYNAMIC ] RESULT SETS INTEGER
| LANGUAGE { JAVA }
|
DeterministicCharacteristic
| EXTERNAL NAME
string
| PARAMETER STYLE JAVA
| EXTERNAL SECURITY { DEFINER | INVOKER }
| { NO SQL | MODIFIES SQL DATA | CONTAINS SQL | READS SQL
DATA }
}
Anything between
[]
is optional, the
*
to the right of
[]
indicates that anything
betweenthesemetacharacterscanappearzeroormoretimes,the
{}
metacharacterssur-
round a list of items, and
|
separates possible items—only one of these items can be
specified.
For example,
CREATE PROCEDURE FIRE(IN ID INTEGER) PARAMETER
STYLE JAVA LANGUAGE JAVA DYNAMIC RESULT SETS 0 EXTERNAL
NAME 'EmployeeDB.fire'
createsastoredprocedurenamed
FIRE
.Thisproced-
urespecifiesaninputparameternamed
ID
andisassociatedwitha
public static
method named
fire
in a
public
class named
EmployeeDB
.
After creating the stored procedure, you need to obtain a
CallableStatement
implementation instance in order to call that procedure, and you do so by invoking
oneof
Connection
's
prepareCall()
methods;forexample,
CallableState-
ment prepareCall(String sql)
.
The string passed to
prepareCall()
is an
escape clause
(RDBMS-independent
syntax)consistingofanopen
{
,followedbytheword
call
,followedbyaspace,fol-
lowedbythenameofthestoredprocedure,followedbyaparameterlistwith“
?
”place-
holder characters for the arguments that will be passed, followed by a closing
}
.
Note
Escape clauses are JDBC's way of smoothing out some of the differences in
how different RDBMS vendors implement SQL. When a JDBC driver detects escape
syntax,itconvertsitintothecodethattheparticularRDBMSunderstands.Thismakes
escape syntax RDBMS-independent.
Once you have a
CallableStatement
reference, you pass arguments to these
parameters in the same way as with
PreparedStatement
. The following example
demonstrates:
