Oracle Action Columns

One. The following describes the curd operation of the Oracle Database operations column

--Student Tables  studentcreate table STUDENT (      ID number) not NULL,      NAME VARCHAR2,      NO  VARCHAR2 (12), Age number      (3));

Two. modifying table fields

--Add Student Table Class class field declare an_flag number  DEFAULT 0; BEGIN  SELECT COUNT (1) into  an_flag from   user_tab_columns   WHERE table_name= ' STUDENT '   and Column_name= ' CLASS ';  IF an_flag = 0 Then    EXECUTE IMMEDIATE ' ALTER TABLE STUDENT ADD CLASS VARCHAR2 (+) ';    EXECUTE IMMEDIATE ' COMMENT on COLUMN STUDENT. Class is ' student's classroom ';  END IF; end;/

Three. Modifying the type of a table field

--Modify the type of the age field of the student table declare  an_flag number DEFAULT 0; BEGIN  SELECT COUNT (1) into  an_flag from   user_tab_columns   WHERE table_name= ' STUDENT ' and   column_ Name= ' age ';  IF An_flag = 1 then    EXECUTE IMMEDIATE ' ALTER TABLE STUDENT MODIFY Age CHAR (3) ';  END IF; end;/

Four. Modify the name of the table field

--Modify the name of the age field of the student table declare  an_flag number DEFAULT 0; BEGIN  SELECT COUNT (1) into  an_flag from   user_tab_columns   WHERE table_name= ' STUDENT '   and Column_name= ' age ';  IF An_flag = 1 then    EXECUTE IMMEDIATE ' ALTER TABLE STUDENT RENAME COLUMN age to age_to ';  END IF; end;/

Five. Delete a table field

--Modify Student table Delete age field declare  an_flag number DEFAULT 0; BEGIN  SELECT COUNT (1) into  an_flag from   user_tab_columns   WHERE table_name= ' STUDENT ' and   column_ Name= ' age ';  IF An_flag = 1 then    EXECUTE IMMEDIATE ' ALTER TABLE STUDENT DROP COLUMN-age ';  

Oracle Action Columns