Question

我在运行时获取数据库表名（让我们假设来自用户）。我需要查询表并返回几个字段（我知道）。怎么做？

“FOR EACH”不会接受变量名称。所以，我无法使用它。

我经历过动态查询，尤其是SET-BUFFERS（）方法。即便如此，我还需要知道表名。

我需要类似的东西：

DEF VAR tablename AS CHAR. 
tablename = somename.
FOR EACH tablename WHERE ....:
     ...
     ...
END.

有人可以指出我正确的方向吗？

Answer 1

您可以使用动态缓冲区执行动态查询。只需在此示例中替换cTableName变量的值：

/* Replace _file with whatever field you're after */
DEFINE VARIABLE cTableName AS CHARACTER   NO-UNDO INIT "_file".

DEFINE VARIABLE hQuery  AS HANDLE      NO-UNDO.
DEFINE VARIABLE hBuffer AS HANDLE      NO-UNDO.

CREATE BUFFER hBuffer FOR TABLE cTableName.
CREATE QUERY hQuery.

hQuery:SET-BUFFERS(hBuffer).

hQuery:QUERY-PREPARE("FOR EACH " + cTableName).
hQuery:QUERY-OPEN().

REPEAT:
    hQuery:GET-NEXT().
    IF hQuery:QUERY-OFF-END THEN LEAVE.

    DISPLAY hBuffer:BUFFER-FIELD(1):BUFFER-VALUE.

    /* If you know the name of the field you can do: */
    /* DISPLAY hBuffer:BUFFER-FIELD("nameoffield"):BUFFER-VALUE. */

END.


/* Clean up */
hQuery:QUERY-CLOSE().
hBuffer:BUFFER-RELEASE().
DELETE OBJECT hBuffer.
DELETE OBJECT hQuery.

查询名称仅在运行时已知的数据库表

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