計算一個字符串在另外一個字符串裡出現的次數 Aui de la Vega,菲律賓 CREATE FUNCTION NUM_CHARS(INSTRING VARCHAR2, INPATTERN VARCHAR2) RETURN NUMBER IS COUNTER NUMBER; NEXT_INDEX NUMBER; STRING VARCHAR2(2000); PATTERN VARCHAR2(2000); BEGIN COUNTER := 0; NEXT_INDEX := 1; STRING := LOWER(INSTRING); PATTERN := LOWER(INPATTERN); FOR I IN 1 .. LENGTH(STRING) LOOP IF (LENGTH(PATTERN) <= LENGTH(STRING)-NEXT_INDEX+1) AND (SUBSTR(STRING,NEXT_INDEX,LENGTH(PATTERN)) = PATTERN) THEN COUNTER := COUNTER+1; END IF; NEXT_INDEX := NEXT_INDEX+1; END LOOP; RETURN COUNTER; END; 代碼分析： 該代碼不是很復雜，利用NEXT_INDEX加一遞增，對INSTRING做遍歷，從INSTRING字符串的第NEXT_INDEX個字符開始截取 LENGTH(PATTERN)長度的字符串，假如截取的字符串等於PATTERN,則計數器COUNTER+1,在PL/SQL Developer+Oracle10+WINNT 調試成功。
