本文共 4558 字，大约阅读时间需要 15 分钟。

SQL????????

????????????SQL???????????????????????????SQL?????????????????????

??????????

???????????

14. ??????

    SELECT PI() value 3.1415926535897931
    ???PI() ????????3.1415926535897931?

15. ??????

    SELECT sin(PI()/2) value 1
    ???sin(PI()/2) ??1?

16. ?????

    SELECT Asin, Acos, Atan, Atan2
    ???ASIN?ACOS?ATAN?ATAN2 ????????????????????????

17. ??????

    SELECT max(value) value from (select 1 value union select -2 value union select 4 value union select 3 value)a
    SELECT greatest(1,-2,4,3) value from dual
    ???GREATEST ????????????????

18. ?????

    SELECT min(value) value from (select 1 value union select -2 value union select 4 value union select 3 value)a
    SELECT least(1,-2,4,3) value from dual
    ???LEAST ????????????????

19. ????

    SELECT F1, IsNull(F2,10) value from Tbl
    SELECT F1,nvl(F2,10) value from Tbl
    ???NVL ??????????????????

20. ????

    SELECT ascii("a") value
    SELECT ascii("a") value from dual
    ???ASCII ?????????ASCII???

21. ????

    SELECT char(97) value
    SELECT chr(97) value from dual
    ???CHR ????????ASCII???????

22. ?????

    SELECT "11" + "22" + "33" value
    SELECT CONCAT("11","22")||33 value from dual
    ???CONCAT ??????????|| ??????????

23. ?????

    SELECT CHARINDEX("s","sdsq",2) value
    SELECT INSTR("sdsq","s",2) value from dual
    ???INSTR ????????????????

24. ??????

    SELECT substring("abcd",2,2) value
    SELECT substr("abcd",2,2) value from dual
    ???SUBSTR ?????????????

25. ?????

    SELECT STUFF("abcdef", 2, 3, "ijklmn") value
    SELECT Replace("abcdef","bcd","ijklmn") value from dual
    ???STUFF ?????????????????Replace ??????????????

26. ?????

    SELECT Translate("fasdbfasegas","fa","????") value from dual
    ???Translate ????????????????????????

27. ??????

    SELECT len,datalength
    ???LEN ? DATALENGTH ?????????????

28. ?????

    SELECT lower,upper
    ???LOWER ? UPPER ?????????????????

???????????

29. ?????

    SELECT INITCAP("abcd dsaf df") value from dual
    ???INITCAP ????????????????????

30. ?????

    SELECT space(10) + "abcd" value
    SELECT LPAD("abcd",14) value from dual
    ???LPAD ??????????????????

31. ?????

    SELECT "abcd" + space(10) value
    SELECT RPAD("abcd",14) value from dual
    ???RPAD ??????????????????

32. ???

    SELECT ltrim,rtrim,trim
    ???LTRIM?RTRIM ? TRIM ??????????????????????

33. ?????

    SELECT REPLICATE("abcd",2) value
    ???REPLICATE ???????????????

34. ???

    SELECT SOUNDEX("Smith"), SOUNDEX("Smythe") from dual
    ???SOUNDEX ????????????????

35. ????

    SELECT getdate() value
    SELECT sysdate value from dual
    ???GETDATE ? SYSDATE ???????????

36. ??????

    SELECT convert(char(10),getdate(),20) value
    SELECT trunc(sysdate) value from dual
    ???CONVERT ? TO_CHAR ?????????????????

37. ????????

    SELECT convert(char(8),getdate(),108) value
    ???CHAR(8) ? TO_CHAR ???????????????????

38. ??????

    SELECT DATEPART "yyyy-mm-dd", DATENAME "year", "quarter", "month", "dayofyear", "day", "week", "weekday", "hour", "minute", "second", "millisecond"
    ???DATEPART ? DATENAME ????????????????????

39. ??????

    SELECT LAST_DAY(sysdate) value from dual
    SELECT Next_day(sysdate,7) value from dual
    ???LAST_DAY ? Next_day ??????????????????????

40. ??????

    SELECT cast("2004-09-08"as datetime) value
    ???CAST ??????????????????

????

????SQL???????????????????????????????????????????????????????????????????????????????????????????