使用PREPARED语句在Sybase中更新IMAGE列失败

Question

这是ASE 15.7和ESQL / C.使用预准备语句更新CURSOR中的行：

EXEC SQL BEGIN DECLARE SECTION;
CS_IMAGE image[512];
EXEC SQL END DECLARE SECTION;

strcpy(image, "foo");

EXEC SQL PREPARE updt FROM "UPDATE image_test SET nettodaten = ? WHERE CURRENT OF hc_image_test";
EXEC SQL EXECUTE updt USING :image;

来自ASE的消息失败：

** SQLCODE=(-201)
** ASE Error
** Procedure *sq1625128094_1900377684ss* expects parameter
Invalid pointer param number 4, pointer value 0x(nil)
, which was not supplied.

这可能是什么原因？

更新1

我稍微修改了ESQL / C代码，看起来像这样：

strcpy(anweisung, "UPDATE image_test SET katkey = ?, nettodaten = ? WHERE CURRENT OF hc_image_test");
EXEC SQL PREPARE updt FROM :anweisung;
EXEC SQL EXECUTE updt USING :key, :blobfld;
EXEC SQL CLOSE hc_image_test;

错误保持与上面相同。但是，通过CPRE查看生成的C代码可以看到一个有趣的细节：

   /*
   ** SQL STATEMENT: 17
   ** EXEC SQL EXECUTE updt USING :key, :blobfld;
   */
   {
        _SQL_CT_HANDLES * _sql;
       _sqlinitctx(&_sql, CS_CURRENT_VERSION, CS_TRUE, &sqlca, (long
           *)NULL, (CS_CHAR *)NULL);
       if (_sql != (_SQL_CT_HANDLES *) NULL)
       {
           _sql->stmtData.persistent = CS_FALSE;
           _sql->stmttype = SQL_EXECUTE;
           _sql->connName.lnlen = CS_UNUSED;
           _sql->stmtName.fnlen = 4;
           strcpy(_sql->stmtName.first_name, "updt");
           if ((_sql->retcode = _sqlprolog(_sql)) == CS_SUCCEED)
           {
               _sql->retcode = ct_dynamic(_sql->conn.command,
                   CS_EXECUTE, "updt", 4, NULL, CS_UNUSED);
               if (_sql->retcode == CS_SUCCEED)
               {
                   _sql->dfmtCS_INT_TYPE.count = 0;
                   _sql->dfmtCS_INT_TYPE.status = CS_INPUTVALUE;
                   _sql->retcode = ct_param(_sql->conn.command,
                       &_sql->dfmtCS_INT_TYPE, &key, (CS_INT)
                       CS_UNUSED, (CS_SMALLINT) 0);
                   _sql->dfmtCS_INT_TYPE.status = 0;
               }

               _sql->retcode = ct_send(_sql->conn.command);
               _sql->hastate = (_sql->retcode == CS_RET_HAFAILOVER);
               _sql->retcode = _sqlResults(_sql);
               _sql->retcode = _sqlepilog(_sql);
           }

           if (sqlca.sqlcode < 0)
           {
               error_handler();
           }

正如上面所看到的，指向主变量CS_INT :key的指针通过调用ct_param()放入内部结构，但不是对主变量CS_IMAGE :blobfld的任何引用。这就是为什么ASE抱怨缺少参数值，因为它在准备好的?声明中看到两个问号UPDATE。这在某种程度上看起来像是CPRE编译器中的一个错误而不是ASE本身。

Answer 1

我通过我们的维护合同联系了SAP公司（发行号为390674/2018），一些工程师正在研究这个CPRE问题......

目前，我正在添加CPRE生成的C代码，在ct_send（）调用之前，以下代码行将缺少的引用添加到IMAGE列：

                   /* additional code for host var :blobfld */
                   if (_sql->retcode == CS_SUCCEED)
                   {
                       _sql->dfmtCS_IMAGE_TYPE.count = 0;
                       _sql->dfmtCS_IMAGE_TYPE.maxlength = (CS_INT) 65535;
                       _sql->dfmtCS_IMAGE_TYPE.format = CS_FMT_UNUSED;
                       _sql->dfmtCS_IMAGE_TYPE.status = CS_INPUTVALUE;
                           _sql->retcode = ct_param(_sql->conn.command,
                               &_sql->dfmtCS_IMAGE_TYPE, blobfld, (CS_INT) ImageLengthField,
                               (CS_SMALLINT) 0);
                       _sql->dfmtCS_IMAGE_TYPE.status = 0;
                   }
                   /* end of additional code for host var :blobfld */

                   _sql->retcode = ct_send(_sql->conn.command);
                   ...

一切正常。