我们常遇到一个存储过程要做都种排序的情况。通常order by 的条件只有一个固定的,这是远远不够的。需要用一个变量来替换它,而Oracle有不能识别Order by后面的字符串。该怎么办呢?先看看我的一个糟糕方案: IF myorderby=''''OBJECTID DESC'''' then --按名称排序 OPEN outcur FOR SELECT * FROM( SELECT rownum rowno,t.* FROM ( SELECT OBJECTID , HITS,POSTTIME FROM CARTOON ORDER BY OBJECTID DESC) t WHERE rownum<endRow) WHERE rowno>=startRow;
elsif myorderby=''''HITS DESC'''' then --按点击率排序 OPEN outcur FOR SELECT * FROM( SELECT rownum rowno,t.* FROM ( SELECT OBJECTID , HITS,POSTTIME FROM CARTOON ORDER BY HITS DESC'''') t WHERE rownum<endRow) WHERE rowno>=startRow;
else --按时间排序 OPEN outcur FOR SELECT * FROM( SELECT rownum rowno,t.* FROM ( SELECT OBJECTID , HITS,POSTTIME FROM CARTOON ORDER BY HITS DESC'''') t WHERE rownum<endRow) WHERE rowno>=startRow;
END IF;
这虽然是通常使用的两种排序方式得以功过,但显得繁杂而且不够通用。 这时我的同事的好办法: --------------------------------------------------------------------------- IF (myorderby is not null) then mysql:=''''SELECT * FROM( SELECT rownum rowno,t.* FROM ( SELECT OBJECTID , HITS,POSTTIME FROM CARTOON ORDER BY ''''|| myorderby || '''') t WHERE rownum<'''' || endRow || '''') WHERE rowno>='''' || startRow; else mysql:=''''SELECT * FROM( SELECT rownum rowno,t.* FROM ( SELECT OBJECTID , HITS,POSTTIME FROM CARTOON ORDER BY posttime DESC) t WHERE rownum<'''' || endRow || '''') WHERE rowno>='''' || startRow; END IF;