返回指定行數之間的查詢結果
2024-07-21 02:38:43
供稿：網友
如何返回指定行數之間的查詢結果，以實現web記錄分頁，在Oracle中有許多的方法，這里僅僅列出了4種，希望能對大家有所幫助，大家可以根據不同需要選擇下面的script
1）select ... where rownum < 50 minus select ... where rownum < 30
這個方法因為用到了minus操作符，所以速度會受影響?！?
2）
SELECT results.* FROM
( SELECT t2.*, rownum rownumber FROM
( SELECT t.* FROM mv_table t WHERE ORDER BY col1) t2) results
WHERE results.rownumber BETWEEN 30 and 50 ORDER BY col1
3）
定義cursor x, 2.fetch x a,b,c; loop ...... end loop;
其中用兩個循環變量和一個FLAG變量，分別表示，當前的記錄數，屬于第幾頁的， 及第一頁面?！?
ps;
j:=to_number(kafyf);
i:=1;
open cx;
loop fetch cx into col1,col2,col3,col4,col5,col6;
if cx%NOTFOUND then exit; end if;
if i>=j then
htp.tableRowOpen;
htp.tableData(col1);
htp.tableData(col2);
htp.tableData(col4);
htp.tableData(col5);
htp.tableData(col6);
htp.tableData(col3);
htp.tableRowClose;
i:=i+1;
if i=j+10 then l:=1; exit; end if;
else i:=i+1;
end if;
end loop;
close x;
該方法用到了Oracle web2kit中的OWA_UTIL package。
4）How can one page forward and backwards through a table?
Externalize ROWNUM by implementing queries like this:
SELECT ...
FROM (SELECT ROWNUM rnum, ... FROM ...)
WHERE rnum BETWEEN :low AND :high AND rownum <(:high :low + 1);
where :low and :high are dynamically generated values depending on which result page the user
is viewing. Typically, they are used to show "Next 15 matches", "PRevious 15 matches" links at the
bottom of each page.
