OpenEdge中的靜態查詢和動態查詢

Question

問題非常普遍，讓我們從代碼可讀性，靈活性和偏離表現的角度來看OpenEdge中的每個優缺點。

靜態查詢：

+ readability: convenient `buffer.field` notation 
+ performance: higher (supposedly, need comments) 
-/+ "global scope" allows to handle all previously used buffers, but could lead 
       to ambiguousness, so you'll have to clarify it with a table 
       name (table.field instead of field) 
- flexibility: you cannot alternate predicate-expression much, 
       even IF function is not recommended (can affect performance)  

動態查詢：

+ flexibility: you can build predicate-expression completely runtime 
+ flexibility: you can work with each field not specifying its name, 
       f.e. you can process all fields of certain record in cycle 
+ flexibility: are reusable (need comments on this point) 
+/- "local scope" allows to use only buffers specified in `SET-BUFFERS` method 
- readability: a little more code to write 
- performance: slightly slower (not sure) 

補充和更正的歡迎。以及任何相關閱讀的鏈接。

Answer 1

靜態查詢的過濾條件可以「飛」來改變，像這樣：

DEFINE QUERY q-name FOR table-name. 
DEFINE VARIABLE h-qry AS HANDLE  NO-UNDO. 
h-qry = QUERY q-name:HANDLE. 
h-qry:QUERY-PREPARE("for each table-name where table-name.field-name = 1"). 

從這裏查詢被視爲與任何正常的靜態查詢。可讀性：「buffer-handle：buffer-field（」field-name「）：buffer-value」結構指動態緩衝區 - 在動態查詢中使用靜態緩衝區是完全可以接受的（通過BUFFER表名：HANDLE），所以動態查詢緩衝區可以使用w /靜態緩衝區，並不總是需要使用它的句柄去引用一個字段。

性能：上次我做了比較，動態查詢對於相同查詢條件比靜態查詢慢。好處是它們比靜態查詢更靈活。

可重用性：一旦設置了動態查詢的緩衝區結構AFAIK，它就無法更改。雖然它可以重新打開一個新的過濾條件相同的靜態查詢。