使用DBCO配置的数据库连接，ABAP可以轻松操作外部数据库。
但如果外部数据源是通过HANA SDI建立的VIRTUAL TABLE，则使用传统的EXEC SQL方式传WHERE条件无效。虽然最终返回给ABAP的数据是按WHERE条件过滤后的值，但监控SDI日志可以发现其原理是先取出对方表的全部数据、再在SDI中过滤后返回给SAP，这会造成非常严重的性能问题。
使用类的方式执行NATIVE SQL则完美解决了这个问题，核心类主要包括以下几个：
CL_SQL_CONNECTION
CL_SQL_STATEMENT
CL_SQL_RESULT_SET
以下为ABAP使用类的方式操作外部数据库的一个小DEMO:
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*&---------------------------------------------------------------------* *& Report ZTEST011 *&---------------------------------------------------------------------* *& *&---------------------------------------------------------------------* REPORT ZTEST011. TYPES: BEGIN OF TYP_SQL_VIEW, VBELN TYPE TXT50, POSNR TYPE TXT50, MATNR TYPE TXT50, QUANT TYPE TXT50, PRICE TYPE TXT50, CONDI TYPE TXT50, KUNNR TYPE TXT50. TYPES:END OF TYP_SQL_VIEW. DATA: LS_NSQL TYPE TYP_SQL_VIEW, LT_NSQL TYPE TABLE OF TYP_SQL_VIEW. DATA: LR_SQL_CONNECTION TYPE REF TO CL_SQL_CONNECTION, LR_SQL_STATEMENT TYPE REF TO CL_SQL_STATEMENT, LR_SQL_RESULT_SET TYPE REF TO CL_SQL_RESULT_SET, LR_SQL_EXCEPTION TYPE REF TO CX_SQL_EXCEPTION, LR_SQL_PARAMETER_INVALID TYPE REF TO CX_PARAMETER_INVALID, LR_PARAMETER_INVALID_TYPE TYPE REF TO CX_PARAMETER_INVALID_TYPE, LR_DATA TYPE REF TO DATA, LV_WHERE_CLAUSE_STATEMENT TYPE STRING, LV_ERROR_TEXT TYPE STRING, LV_WHERE_MANDT TYPE STRING, LV_WHERE_SPRAS TYPE STRING. DATA LV_ORDER TYPE C LENGTH 10 VALUE '1000002050'. DATA LV_TABLE TYPE C LENGTH 10 VALUE 'VT001_S4D'. *get dbco connection. TRY. CALL METHOD CL_SQL_CONNECTION=>GET_CONNECTION EXPORTING CON_NAME = 'DBCO_HANA' SHARABLE = SPACE RECEIVING CON_REF = LR_SQL_CONNECTION. CATCH CX_SQL_EXCEPTION . ENDTRY. *build sql stamement. CALL METHOD LR_SQL_CONNECTION->CREATE_STATEMENT RECEIVING STMT_REF = LR_SQL_STATEMENT. DATA(LV_STATEMENT) = | SELECT * FROM { LV_TABLE } WHERE VBELN = '{ LV_ORDER }'|. *execute sql. LR_SQL_RESULT_SET = LR_SQL_STATEMENT->EXECUTE_QUERY( LV_STATEMENT ). "参考LT_NSQL的数据结构创建通用数据结构LR_DATA. GET REFERENCE OF LT_NSQL INTO LR_DATA. "解析结果集到LR_DATA. "1)Set Internal Table as Output Parameters LR_SQL_RESULT_SET->SET_PARAM_TABLE( LR_DATA ). "2)Read Next Set of Data Records into the Internal Table. LR_SQL_RESULT_SET->NEXT_PACKAGE( ). *现在数据在内表LT_NSQL[]中. *关闭数据库连接. TRY. CALL METHOD LR_SQL_CONNECTION->CLOSE. CATCH CX_SQL_EXCEPTION . ENDTRY. |