【Gbase 8s】自定义MySQL兼容函数

一、find_in_set
find_in_set(s1,s)函数，在s字符串集中查找s1的位置

-- find_in_set
drop function if exists find_in_set;
create function find_in_set(str varchar(255),strlist varchar(8192)) returns int;
  define currp  int; 
  define lastp  int; 
  define sepnum int;
  define strlen int;
  define strtmp varchar(8192);
 
  let lastp  = 1;
  let sepnum = 0;
  let strtmp = strlist || ","; 
  let strlen = length(strtmp);
  FOR currp = 1 TO strlen
    IF substr(strtmp,currp,1) = ',' THEN
      let sepnum = sepnum + 1;
      IF substr(strtmp,lastp,currp - lastp) = str THEN
        RETURN sepnum;
      END IF;
      let lastp = currp + 1;
    END IF;
  END FOR;
  RETURN 0;
end function;

二、hexstr
hexstr(str)函数，替代hex，将字符串转换成16进制字符串

-- hexstr, instead of hex
drop function if exists hexstr;
create function hexstr(pstr varchar(8192))
returns varchar(8192) with (not variant)
  define curpos smallint;
  define curval smallint;
  define tmpstr varchar(8192);
  on exception
    return null;
  end exception;
    
  let tmpstr = "";
  for curpos = 1 to length(pstr)
    let curval = ascii(substr(pstr,curpos,1));
    let tmpstr = tmpstr || substr(hex(curval),9);
  end for;
  return tmpstr;
end function;

三、unhex

-- unhex
drop function if exists unhex;
create function unhex(pstr varchar(8192))
returns varchar(8192) with (not variant)
  define curpos smallint;
  define curval smallint;
  define tmpint smallint; 
  define tmpstr varchar(8192);
  on exception
    return null;
  end exception;
   
  let tmpint = 0;
  let tmpstr = "";
  for curpos = 1 to length(pstr)
    let curval = 0;
    case lower(substr(pstr,curpos,1)) 
      when 'a' then let curval = 10;
      when 'b' then let curval = 11;
      when 'c' then let curval = 12;
      when 'd' then let curval = 13;
      when 'e' then let curval = 14;
      when 'f' then let curval = 15;
      else let curval = substr(pstr,curpos,1);
    end case;
    if mod(curpos,2) = 1 then
      let tmpint = curval * 16;
    else
      let tmpint = tmpint + curval;
      let tmpstr = tmpstr || chr(tmpint);
    end if;
  end for;
  return tmpstr;
end function;

四、group_concat
group_concat聚集函数

-- group_concat
drop aggregate if exists group_concat;
create aggregate group_concat with
(
  init = str_sum_init,
  iter = str_sum_iter,
  combine = str_sum_combine
);

五、aes_encrypt
aes_encrypt(str,key)函数，AES加密函数

-- aes_encrypt
drop function if exists aes_encrypt;
create function aes_encrypt(p1 varchar(8192), p2 varchar(8192))
returns varchar(8192);
  if p1 is null or p1 = '' then
	    return null;
	  end if;
	  set encryption password(p2);
	  return encrypt_aes(p1);
end function;

六、aes_decrypt
aes_decrypt(str,key)函数，AES解密函数

-- aes_decrypt
drop function if exists aes_decrypt;
create function aes_decrypt(p1 varchar(8192), p2 varchar(8192))
returns varchar(8192);
  if p1 is null or p1 = '' then
	    return null;
	  end if;
	  set encryption password(p2);
	  return decrypt_char(p1);
end function;

七、weekofyear
weekofyear(dt)函数，日期dt是所在年的第几周

drop function if exists weekofyear(datetime year to second);
-- day of year, first week is 01-01 ~ 01-07
create function weekofyear(p_datetime datetime year to second) 
returns int with (not variant);
  return trunc(1 + (p_datetime - TRUNC(p_datetime, 'YEAR')) / 7);
end function;

八、weekofmonth
weekofmonth(dt)函数，日期dt是所在月的第几天

drop function if exists weekofmonth(datetime year to second);
-- day of month, first week is 01~07
create function weekofmonth(p_datetime datetime year to second) 
returns int with (not variant);
  return trunc(1 + (p_datetime - TRUNC(p_datetime, 'MONTH')) / 7);
end function;

九、dayofyear
dayofyear(dt)函数，日期dt是所在年的第几天

drop function if exists dayofyear(datetime year to second);
-- day of year
create function dayofyear(p_datetime datetime year to second) 
returns int with (not variant);
  return trunc(1 + (p_datetime - TRUNC(p_datetime, 'YEAR')));
end function;

十、datediff
datediff(dt1,dt1)函数，两个日期的差值

-- datediff
drop function if exists datediff;
create function datediff(p1 datetime year to fraction(5), p2 datetime year to fraction(5))
returns int with (not variant);
  on exception
    return null;
  end exception;
  return substr(p1 - p2,1,9)::int;
end function;

十一、unix_timestamp
unix_timestamp(dt)函数，将日期时间dt转换为自1970-01-01 08:00:00开始的秒数

drop function if exists UNIX_TIMESTAMP(datetime year to second);
-- unix_timestamp
create function UNIX_TIMESTAMP(datestr datetime year to second) 
returns bigint with (not variant);
  define rc_char varchar(30);
  if datestr < datetime(1970-01-01 08:00:00) year to second then
    let rc_char = datetime(1970-01-01 08:00:00) year to second - datestr;
    return 0 - ((replace(substr(rc_char,1,9),'-')*86400)::bigint + substr(rc_char,17,2)*1 + substr(rc_char,14,2)*60 + substr(rc_char,11,2)*3600);
  else
    let rc_char = datestr - datetime(1970-01-01 08:00:00) year to second;
    return ((substr(rc_char,1,9)*86400)::bigint + substr(rc_char,17,2)*1 + substr(rc_char,14,2)*60 + substr(rc_char,11,2)*3600);
  end if;
end function ;

十二、from_unixtime
from_unixtime§函数，生成自1970-01-01 08:00:00开始p秒的日期时间值

drop function if exists from_unixtime;
-- from_unixtime
create function from_unixtime(p bigint) 
returns varchar(20) with (not variant);
  define v_day int;
  define v_hour int;
  define v_min int;
  define v_sec int;
  define v_dt datetime year to second;
  on exception
    return null;
  end exception;
   
  let v_day = p / 86400;
  let v_dt = datetime(1970-01-01 08:00:00) year to second + v_day units day;
   
  let v_hour = mod(p,86400) / 3600;
  let v_dt = v_dt + v_hour units hour;
   
  let v_min = mod(p,3600) / 60;
  let v_dt = v_dt + v_min units minute;
   
  let v_sec = mod(p,60);
  let v_dt = v_dt + v_sec units second;
   
  return to_char(v_dt,'yyyy-mm-dd hh24:mi:ss');
end function;

十三、makedate
makedate(d,y)函数，生成d年第y天的日期

drop function if exists makedate;
-- makedate
create function makedate(dt int,dy int)
returns date with (not variant);
  return mdy(1,1,dt) + (dy - 1) units day;
end function;

十四、maketime
maketime(h,m,s)函数，生成时间hh:mi:ss

drop function if exists maketime;
-- maketime
create function maketime(dh int, dm int, ds int)
returns char(8) with (not variant);
  if dh < 0 or dh > 23 or dm < 0 or dm > 59 or ds < 0 or ds > 59 then
    return null;
  else
    return lpad(dh,2,'0') || ':' || lpad(dm,2,'0') || ':' || lpad(ds,2,'0');
  end if;
end function;

十五、strcmp
strcmp(s1,s2)函数，比较s1，s2两个字符串

drop function if exists strcmp;
-- strcmp
create function strcmp(str1 varchar(8192), str2 varchar(8192))
returns smallint with (not variant);
  on exception
    return null;
  end exception;
  if str1 = str2 then
    return 0;
  elif str1 > str2 then
    return 1;
  else
    return -1;
  end if;
end function;

十六、repeat
repeat(s,n)函数，输出n个s

-- repeat
drop function if exists repeat;
create function repeat(str varchar(1024), n smallint)
returns varchar(32765) with (not variant);
  define rc varchar(32765);
  define i  smallint;
  on exception
    return null;
  end exception;
  let rc = '';
  for i = 1 to n
    let rc = rc || str;
  end for;
  return rc;
end function;

十七、now
now() 函数，获取当前系统时间

-- now
drop function if exists now;
create function now()
returns datetime year to fraction(5);
  return current year to second;
end function;

十八、date_format
date_format(dt,fmt)函数，格式化日期时间

-- date_format
drop function if exists date_format;
create function date_format(p1 datetime year to fraction(5), p2 varchar(20))
returns varchar(40) with (not variant);
  define fmt varchar(20);
  on exception
    return null;
  end exception;
  let fmt = replace(p2,'i','M');
  let fmt = replace(fmt,'s','S');
  return gbase_to_char(p1,fmt);
end function;

十九、str_to_date
str_to_date(s,fmt)函数，将字符串格式化转换为日期时间

-- str_to_date
drop function if exists str_to_date;
create function str_to_date(p1 varchar(40), p2 varchar(20))
returns datetime year to fraction(5) with (not variant);
  define fmt varchar(20);
  on exception
    return null;
  end exception;
  let fmt = replace(p2,'i','M');
  let fmt = replace(fmt,'s','S');
  return gbase_to_date(p1,fmt);
end function;

二十、datediff
datediff(dt1,dt2)函数，计算两个时间的天数差值

-- datediff
drop function if exists datediff;
create function datediff(p1 datetime year to fraction(5), p2 datetime year to fraction(5))
returns int with (not variant);
  on exception
    return null;
  end exception;
  return substr(p1 - p2,1,9)::int;
end function;

二十一、to_days
to_days(dt)函数，将日期转换为自0000-00-00开始的天数

-- to_days
drop function if exists to_days;
create function to_days(p1 datetime year to fraction(5))
returns int with (not variant);
  on exception
    return null;
  end exception;
  return 366 + substr(p1 - mdy(1,1,1),1,9)::int;
end function; 

二十二、from_days
from_days§函数，计算自0000-00-00开始天数p的日期

-- from_days
drop function if exists from_days;
create function from_days(p1 int)
returns varchar(40) with (not variant);
  on exception
    return null;
  end exception;
  if p1 < 366 then
    return '0000-00-00';
  else
    return gbase_to_char(mdy(1,1,1) + (p1 - 366) units day,'%Y-%m-%d');
  end if;
end function;

二十三、period_diff
period_diff(p1,p2)函数，格式化日期的月份差

-- period_diff
drop function if exists period_diff;
create function period_diff(p1 int, p2 int)
returns int with (not variant);
  define vm1 int;
  define vm2 int;
  on exception
    return null;
  end exception;
  if p1 < 9999 then
    let p1 = p1 + 200000;
  end if;
  let vm1 = (p1 / 100 - 1970) * 12 + mod(p1, 100);
  if p2 < 9999 then
    let p2 = p2 + 200000;
  end if;
  let vm2 = (p2 / 100 - 1970) * 12 + mod(p2, 100);
  return vm1 - vm2;
end function;

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