Oracle Database Experience Series---first

1) Change the date display type of the results queried in SQL developer in Oracle 11g R2, that is, the setting of the session date type:
Alter session Set Nls_date_format = ' Yyyy-mm-dd HH24:MI:SS ';
Oracle Plus fields:
ALTER TABLE operator_daily Add (op_type number (11));

2) the function Dense_rank () is a sequential sort, with two second names still followed by third place.

3) the function rank () is a jumping sort, with two second names followed by the fourth place (also within each grouping)

4) view table constraint:Select * from user_constraints where table_name= ' parent ';

CONSTRAINT_TYPE:C: Check p:primary key R:foreign key U:unique

5) Create tablespace MCP datafile ' E:\oracle\tablespace\data.dbf ' size 512m;

6) When the Oracle field is VARCHAR2, the conversion takes the SUBSTR function instead of the Tu_char

7) When there is a case in the statement when the group by should be even if the conditions inside the cases should also be written in or not conform to the group rules;

8) Backup table:
CREATE TABLE table_name AS SELECT * FROM Table_namexxx

Oracle Database Experience Series---first