[Share] common conversions from Oracle migration to DB2

Because of the project requirements, we need to transfer the items on Oracle to DB2, So we collected some precautions for modification and shared them with you.
 

Examples of implementing the same functions of Oracle and DB2 (taking Oracle8i and DB2 7.x as examples, tested)
Obtain the first N records	Oracle	Select * From tablename where rownum <= N;
	DB2	Select * From tablename fetch first n rows only;
Obtain system date	Oracle	Select sysdate from dual;
	DB2	Select current timestamp from sysibm. sysdummy1;
Null Value Conversion	Oracle	Select productid, loginname, nvl (cur_rate, '0') from tablename;
	DB2	Select productid, loginname, value (cur_rate, '0') from tablename;
Type conversion	Oracle	Select to_char (sysdate, 'yyyy-MM-DD hh24: MI: ss') from dual;
	DB2	Select varchar (current timestamp) from sysibm. sysdummy1;
		■ Oracle Data Type Change functions: to_char (), to_date (), to_number (), etc. If you only use year, month, day, etc., you can use to_char (sysdate, 'yyyy'), to_char ('mm'), to_char ('dd. Only the year, month, and day trunc (sysdate) are used, and the time, minute, and second to_char (sysdate, 'hh24: MI: ss') are used ').
		■ DB2 data type change functions: Char (), varchar (), INT (), date (), time (), and so on; method of obtaining year, month, and day: year (current timestamp), month (current timestamp), Day (current timestamp), hour (current timestamp), minute (current timestamp), second (current timestamp ), microsecond (current timestamp). Date (current timestamp) can be used only for year, month, and day, and time (current timestamp) can be used ). Char () is a fixed-length string (1-255), varchar () is not a fixed-length string (1-32672) Date, time form into character form: Char (current date), char (current time) Converts a string to a date or time format: Timestamp ('2017-10-20 12:00:00 '), date ('2017-10-20'), date ('2017/123 '), time ('12: 00: 00 ')
Quickly clear large tables	Oracle	Truncate table tablename;
	DB2	Alter table tablename active not logged initially with empty table;
Rowid	Oracle	It is unique in the database and can be obtained in the program.
	DB2	This concept exists, but cannot be obtained by the program. Solution to be determined (Senior contact my caoxicao@hotmail.com ).
To_number	Oracle	Select to_number ('123') from dual;
	DB2	Select cast ('200' as integer) from sysibm. sysdummy1;
Copy and create a table	Oracle	Create Table A as select * from B;
	DB2	Create Table A like B;