如何通过 JDBC 从 Db2 匿名块 return 动态结果集？

Question

我正在查看 Db2 LUW feature "returning result sets from SQL"，它的工作方式似乎与 MySQL、SQL 服务器中的可能方式类似，通过运行一个简单的 SELECT 来自任何过程逻辑，或在 Oracle 中使用 DBMS_SQL.RETURN_RESULT。以下匿名块似乎是有效的：

BEGIN
  DECLARE i INTEGER DEFAULT 1;
  WHILE i < 10 DO
    BEGIN 
      DECLARE cur CURSOR WITH RETURN TO CLIENT FOR SELECT i FROM sysibm.dual;
      OPEN cur;
      SET i = i + 1;
    END;
  END WHILE;
END

然而，它产生了这个警告，并且没有任何结果被获取。海狸：

Procedure "BEGIN...END" returned "9" query result sets, which exceeds the defined limit "0".. SQLCODE=464, SQLSTATE=0100E, DRIVER=4.26.14

如果这是一个程序，我必须声明：

DYNAMIC RESULT SETS n

但是我怎样才能在匿名块中声明它呢？

Answer 1

如果不是来自过程，则不能return结果集

见docs

WITH RETURN Specifies that the result table of the cursor is intended to be used as a result set that will be returned from a procedure. WITH RETURN is relevant only if the DECLARE CURSOR statement is contained with the source code for a procedure. In other cases, the precompiler might accept the clause, but it has no effect.

我知道这可能只是一个例子，但是 return 1 到 10 之间的整数不需要过程语句，下面的查询也可以：

with loop(k) as (
  values 1
  union all select k+1 from loop where k < 10
)
select * from loop order by k

Answer 2

尝试以下操作。它至少适用于我的 11.1。

    String str = 
        "begin"
    + "  declare l_c CURSOR; "
    + "  set l_c = cursor with hold for select empno from employee; "
    + "  open l_c; "
    + "  set ? = l_c; "
    + "end";
    CallableStatement st = null;
    ResultSet rs = null;
    try 
    {
        st = con.prepareCall(str);
        st.registerOutParameter (1, com.ibm.db2.jcc.DB2Types.CURSOR); 
        st.execute(); 
        rs = (java.sql.ResultSet) st.getObject(1);
        if (rs != null)
        {
          while (rs.next()) 
            System.out.println(rs.getString(1));
          rs.close();           
        }
    } ...

如何通过 JDBC 从 Db2 匿名块 return 动态结果集？

How to return dynamic results sets from a Db2 anonymous block via JDBC?

db2

jdbc

db2-luw