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

The following article mainly introduces the comparison between common DB2 functions and Oracle functions. If you are curious about the comparison between common DB2 functions and Oracle functions, the following articles will provide you with reliable knowledge. The following is a detailed description of the article.

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  
 
 

Converted 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  
 
 

DB2 common functions compared with Oracle 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, <pos>: Find the location where arg1 first appears in arg2, specify 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, <length>: returns the length starting from the pos position in arg1. If the length is not specified, the remaining characters are returned.

Common examples:

Null Value processing function

 
 

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

Remove space:

Oracle: select trim ('abc') from dual; spaces at both ends are removed by default.

Select trim (heading ''from 'abc') from dual only removes spaces on the left end, and can also be used to remove other characters

Select trim (trailing ''from 'abc') from dual only removes spaces on the right side. It can also 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  
 
 

DB2 common functions compared with Oracle return string uppercase values, actually use 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.