动态sql

我参照官网上的指南：教程，

如下写了一个例子，但是在执行这个存储过程时bigquery的值写什么，以及这个存储过程的外部调用语句该怎么写？
DROP PROCEDURE IF EXISTS P_GenerateCode;
CREATE PROCEDURE P_GenerateCode
(
tabid int,
tabname NVARCHAR(100)
)

EXEC SQL BEGIN DECLARE SECTION;
char bigquery[270] = "begin work;";
EXEC SQL END DECLARE SECTION;
stcat ("SELECT * from systables WHERE tabid = ? and ", bigquery);
stcat ("tabname = ?;', bigquery);
EXEC SQL prepare bigq from :bigquery;

EXEC SQL execute bigq using :tabid, :tabname;

EXEC SQL commit work;

END PROCEDURE;