同一交叉表的动态SQL例子

DECLARE

 TYPE list IS TABLE OF t_stu.subject%TYPE INDEX BY BINARY_INTEGER;
 subject_list list;
 v_pro_num NUMBER; 
 sql_str VARCHAR(255); 

BEGIN

 SELECT COUNT(DISTINCT subject) INTO v_pro_num FROM t_stu;
 sql_str := 'SELECT id '; 
 
 FOR v_idx in 1..v_pro_num LOOP
 
  IF v_idx = 1 THEN
  
   SELECT DISTINCT subject INTO subject_list(v_idx) FROM t_stu WHERE rownum = 1;
   
  ELSE
  
   SELECT subjectINTO subject_list(v_idx)
   FROM (SELECT DISTINCT subject, rownum row_num FROM t_stu WHERE rownum < v_idx + 1) 
   WHERE row_num = v_idx;
   
  END IF;
  
  sql_str := sql_str || ', SUM(DECODE(subject,''' || subject_list(v_idx) || ''',score,0)) AS ' || subject_list(v_idx);
  
 END LOOP;
 
 sql_str := sql_str || ' FROM t_stu GROUP BY id';
 DBMS_OUTPUT.PUT_LINE('sql--->' || sql_str);
  
 EXEC IMMEDIATE sql_str;
  
END;

 原始表结构：

SID SUBJECT SCORE
1 数学 99
1 英语 68
1 法律 79
2 数学 92
2 英语 72
2 法律 96

实现后的：

SID	数学	英语	法律
1	99	68	79
2	92	72	96