Oracle data table creation, query, constraints, and other operations

1. Create a table, delete a table, copy a table

CREATE TABLE stuinfo-- creating learner information Tables

（

Stuno Char (6) NOT NULL

Stuname varchar (2) not nul,

Stuage number (3,0) NOT NULL

）

Create a new table copy the Learner Information table is:CREATE TABLE StuInfo2 as SELECT * from Stuinfo;

Delete Table: 1, drop table Table 2, truncate tables;

2, the table structure of the query: DESC table name;

3, change the table name: ALTER TABLE old table name rename to new table name;

Add columns: ALTER TABLE table Add (column name type, column name type);

Modify columns: ALTER TABLE table modify (column name type, column name type);

Delete a column: ALTER TABLE table drop column name; Delete multiple columns: ALTER TABLE Table drop (column 1, column 2);

4, add a constraint to the table, the EMP table Deptno as a Foreign Key reference dept Table Deptno

ALTER TABLE EMP Add constraint pk_test foreign KEY (deptno) References dept (DEPTNO);

5. Add a PRIMARY KEY constraint to the table

ALTER TABLE EMP ADD constraint Pk_emp_deptno primary key (DEPTNO);

6. Delete the constraint:

ALTER TABLE EMP drop constraint Pk_emp_deptno;

7. Disabling and enabling constraints:

ALTER TABLE Table Dsable| | Enable constraint constraint name;

Oracle data table creation, query, constraints, and other operations