如何获取自定义 Oracle function 参数定义

Question

We need to get the Custom Function parameter list from Java jdbc.

we define the custom function in a package named mypkg .

I am using oracle as the database.

we can run command like desc mypkg.customFunction in the console.

but I want to know how to get similar information from java side.

Answer 1

If you have a stored function (and not a stored procedure), then method getFunctionColumns will retrieve details of its parameters.

Consider the following code (which uses try-with-resources ).

Note that there appears to be a bug in Oracle's JDBC driver where method getFunctionColumns retrieves the same parameter multiple times. The below code will display each parameter's details once only.

More explanations after the code.

String url = "jdbc:oracle...";
try (Connection conn = DriverManager.getConnection(url)) {
    DatabaseMetaData dbmd = conn.getMetaData();
    ResultSet rs = dbmd.getFunctionColumns("mypkg", "<schema>", "customFunction", "%");
    String lastColumn = null;
    while (rs.next()) {
        String columnName = rs.getString(4);
        if (columnName != null  &&  !columnName.equals(lastColumn)) {
            String type;
            switch (rs.getShort(5)) { // parameter type (IN, OUT or IN-OUT)
                case DatabaseMetaData.functionColumnIn:
                    type = "IN";
                    break;
                case DatabaseMetaData.functionColumnInOut:
                    type = "IN OUT";
                    break;
                case DatabaseMetaData.functionColumnOut:
                    type = "OUT";
                    break;
                default:
                    type = "unknown";
            }
            System.out.printf("%s %s %s%n",
                              rs.getString(4),  // parameter name
                              type,             // parameter type
                              rs.getString(7)); // data type length
            lastColumn = columnName;
        }
    }
}
catch (SQLException xSql) {
    xSql.printStackTrace();
}

• I assume you know the JDBC connection URL that you need in order to connect to your Oracle database.
• First argument in call to method getFunctionColumns is the PL/SQL package name.
• Second argument in call to method getFunctionColumns is schema. Replace <schema> in the above code with the actual schema name of the owner of mypkg . If you don't know the schema then you can use null. Column 2 of the ResultSet returned by method getFunctionColumns contains the schema name.
• If customFunction is a stored procedure (and not a stored function), then you need method getProcedureColumns .