What are the differences between common DB2 functions and Oracle functions?

The following articles mainly introduce the comparison between common DB2 functions and Oracle functions. If you are curious about common DB2 functions and Oracle functions, this article will unveil the secrets of this article, the following is a detailed description of the main content of the article. I hope you will have a better understanding of it after browsing.

1. type conversion functions: decimal, double, Integer, smallint, real, Hex (arg ),

 
 

  
  
date, time,timestamp,char, varchar 
 
 

Common examples:

-- Convert to string type

 
 

  
  
Oracle: select to_char(15.5000) from dual;  
  
  
DB2:　 select char(15.5000) from sysibm.sysdummy1  
 
 

-- Convert to date and time

 
 

  
  
Oracle: select to_date('2008-01-01','yyyy-mm-dd') from dual;  
  
  
DB2:　 select date('2008-01-01') from sysibm.sysdummy1  
 
 

2. Date: year, quarter, month, week, day, hour, minute, second

Dayofyear (arg): returns the Daily Value of arg within the year.

Dayofweek (arg): returns the Daily Value of arg within a week.

Days (arg): returns the integer representation of the date, from-01-01.

Midnight_seconds (arg): the number of seconds between midnight and arg.

Monthname (arg): returns the month name of arg.

Dayname (arg): returns the week of arg.

Common examples:

Returns the current system time.

 
 

  
  
Oracle: select sysdate from dual;  
  
  
DB2:　 select current date from sysibm.sysdummy1  
 
 

Returns the next day of the current time)

 
 

  
  
Oracle: select sysdate,sysdate + interval '1' day　 from dual;  
  
  
DB2:　 select current date + 1 day from sysibm.sysdummy1  
 
 

3. String functions:

 
 

  
  
length,lcase, ucase, ltrim, rtrim 
 
 

Coalesce (arg1, arg2 ....) : The first non-null parameter in the returned parameter set.

Concat (arg1, arg2): connects two strings: arg1 and arg2.

Insert (arg1, pos, size, arg2): returns one. arg1 is deleted from the pos,

Insert arg2 to this location.

Left (arg, length): returns the leftmost length string of arg.

Locate (arg1, arg2,: searches for the location where arg1 appears for the first time in arg2, specifying pos,

The first position of arg1 appears at the pos of arg2.

Posstr (arg1, arg2): returns the position where arg2 first appeared in arg1.

Repeat (arg1, num_times): returns the string that arg1 is repeated for num_times.

Replace (arg1, arg2, arg3): replace all arg2 in arg1 with arg3.

Right (arg, length): returns a string consisting of the Left length bytes of arg.

Space (arg): returns a string containing arg spaces.

Substr (arg1, pos,: returns the length starting from the pos position in arg1. If the length is not specified, the remaining characters are returned.

Common examples:

DB2 common functions: null value processing functions

 
 

  
  
Oracle: select nvl(null,'aaa') from dual;  
  
  
DB2:　 db2 select coalesce(comm,1000) from staff;  
 
 

Remove space:

Oracle: select trim ('abc') from dual; -- remove spaces at both ends by default

Select trim (heading ''from 'abc') from dual -- remove only spaces on the left side, or remove other characters

Select trim (trailing ''from 'abc') from dual -- removes only the right-side space and can be used to remove other characters

 
 

  
  
DB2:  
  
  
select ltrim(rtrim(' abc ')) from sysibm.sysdummy1  
  
  
select ltrim('　 abc ') from sysibm.sysdummy1  
  
  
select rtrim('　 abc ') from sysibm.sysdummy1  
 
 

Common DB2 functions return string uppercase values, which can be upper

 
 

  
  
Oracle: select upper('abc') from dual;  
  
  
DB2:　 select upper('abc') from sysibm.sysdummy1  
 
 

Or

 
 

  
  
select ucase('abc') from sysibm.sysdummy1 
 
 

Merge strings. Oracle and DB2 can both be the same as the following:

 
 

  
  
Oracle: select concat('abcd','efg') from dual;  
  
  
select 'abcd' || 'efg' from dual;  
  
  
DB2:　 select concat('abcd','efg') from sysibm.sysdummy1  
  
  
select 'abcd' || 'efg' from sysibm.sysdummy1  
 
 

4. mathematical functions:

 
 

  
  
Abs, count, max, min, sum 
 
 

Ceil (arg): returns the smallest integer greater than or equal to arg.

Floor (arg): returns the smallest integer less than or equal to the parameter.

Mod (arg1, arg2): returns the remainder of arg1 divided by arg2. the symbol is the same as that of arg1.

Rand (): returns a random number between 1 and 10.

Power (arg1, arg2): returns the arg2 Power of arg1.

Round (arg1, arg2): rounding to truncation. arg2 is the number of digits. If arg2 is negative, rounding to the number before the decimal point.

Sigh (arg): returns the symbol indicator of arg. -1, 0, 1 indicates.

Truncate (arg1, arg2): truncates arg1. arg2 is the number of digits. If arg2 is a negative number, the arg2 before the decimal point of arg1 is retained.

The above content is a comparison of common DB2 functions with Oracle. I hope you will find some gains.