merge
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xiangwbs
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CREATE TABLE employee_xwbin(
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id NUMBER(4) DEFAULT 1 ,
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name VARCHAR2(20),
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gender CHAR(1) DEFAULT 'M',
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biith DATE,
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salary NUMBER(6,2),
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job VARCHAR2(30),
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deptno NUMBER(2)
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);
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DROP TABLE name4;
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NOT NULL 约束可以确保指定的字段不允许为null
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CREATE TABLE employ_xwbing(
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id NUMBER(4) DEFAULT 1,
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name VARCHAR2(20) NOT NULL,
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gender CHAR(1) DEFAULT 'M',
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birth DATE,
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salary NUMBER(6,2) DEFAULT 1,
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job VARCHAR2(30) DEFAULT 'M',
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deptno NUMBER(2) DEFAULT 1
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)
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DESC xwbing;
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RENAME employ_xwbing TO xwbing;
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DESC xwbing;
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修改表的
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向表中添加新的字段,只能在当前表的末尾追加,可以同时追加多个列,只需要使用逗号隔开即可,与创建声明列的时候语法一样
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ALTER TABLE XWBING ADD(
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HIREDATE DATE DEFAULT SYSDATE
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)
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删除表中现有字段
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DML
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用于修改表中数据,分为:增 删 改
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插入数据
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INSERT INTO XWBING (id,name,job,salary)
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VALUES(1,'JACK','CLERK',5000)
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COMMIT
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插入日期类型,建议使用TO-DATE函数
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可以使用字符串 但是格式必须是'DD-MON-RR'
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由于有语言差异,不推荐
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INSERT INTO XWBING(id,name,job,birth)
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VALUES(2,'ROSE','CLERK',TO_DATE('1992-08-02','YYYY-MM-DD'))
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SELECT *FROM XWBING;
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ALTER TABLE XWBING DROP(HIREDATE)
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修改表中现有字段
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可以修改字段的类型,长度,默认值,非空
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ALTER TABLE XWBING MODIFY(
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job VARCHAR2(40) DEFAULT 'CLERK'
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)
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修改表中现有数据
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将rose的工资改为5500
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UPDATE XWBING SET SALARY=50000 WHERE name='ROSE' 字符串里区分大小写,用''
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修改表中的数据的时候,通常要使用WHERE下限定条件,这样只会将满足条件的记录进行修改,
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若不在指定WHERE则是全表所有的数据都修改
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删除表中数据
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将rose删除
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DELETE FROM EMP_XWBING WHERE name='ROSE'
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DELETE FROM EMP_XWBING
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删除表中数据同样要用WHERE添加过滤条件 否则就是清空表操作
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CREATE TABLE emp_xwbing(
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empno NUMBER(4,0),
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ename VARCHAR2(10),
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job VARCHAR2(9),
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mgr NUMBER(4,0),
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hiredate DATE,
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sal NUMBER(7,2),
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comm NUMBER(7,2),
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deptno NUMBER(2,0)
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)
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SELECT *FROM EMP_XWBING;
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DESC emp_xwbing;
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CREATE TABLE dept_xwbing(
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deptno NUMBER(2,0),
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dname VARCHAR2(14 BYTE),
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loc VARCHAR2(13 BYTE)
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)
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,deptno)
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VALUES(7369,'SMITH','CLERK',7902,TO_DATE('1980/12/17','YYYY-MM-DD'),800.00,20);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,comm,deptno)
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VALUES(7499,'ALLEN','SALESMAN',7698,TO_DATE('1981/02/20','YYYY-MM-DD'),1600.00,300.00,30);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,comm,deptno)
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VALUES(7521,'WARD','SALESMAN',7698,TO_DATE('1981/02/22','YYYY-MM-DD'),1250.00,500.00,30);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,deptno)
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VALUES(7566,'JONES','MANAGER',7839,TO_DATE('1980/4/2','YYYY-MM-DD'),2975.00,20);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,comm,deptno)
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VALUES(7654,'MARTIN','SALESMAN',7698,TO_DATE('1981/9/28','YYYY-MM-DD'),1250.00,1400.00,30);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,deptno)
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VALUES(7698,'BLACK','MANAGER',7839,TO_DATE('1980/5/1','YYYY-MM-DD'),2850.00,30);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,deptno)
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VALUES(7782,'CLARK','MANAGER',7839,TO_DATE('1980/6/9','YYYY-MM-DD'),2450.00,10);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,deptno)
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VALUES(7788,'SCOTT','ANALYST',7566,TO_DATE('1987/4/19','YYYY-MM-DD'),3000.00,20);
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INSERT INTO emp_xwbing(empno, ename,job,hiredate,sal,deptno)
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VALUES(7839,'KING','PRESIDENT',TO_DATE('1981/11/17','YYYY-MM-DD'),5000.00,10);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,comm,deptno)
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VALUES(7844,'TURNER','SALESMAN',7698,TO_DATE('1981/9/8','YYYY-MM-DD'),1500.00,0.00,30);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,deptno)
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VALUES(7876,'ADAMS','CLERK',7788,TO_DATE('1987/5/23','YYYY-MM-DD'),1100.00,20);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,deptno)
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VALUES(7900,'JAMES','CLERK',7698,TO_DATE('1981/12/3','YYYY-MM-DD'),9500.00,30);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,deptno)
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VALUES(7902,'FORD','ANALYST',7566,TO_DATE('1981/12/3','YYYY-MM-DD'),3000.00,20);
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INSERT INTO emp_xwbing(empno, ename,job,mgr,hiredate,sal,deptno)
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VALUES(7934,'MILLER','CLERK',7782,TO_DATE('1982/1/23','YYYY-MM-DD'),1300.00,10);
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INSERT INTO dept_xwbing(deptno,dname,loc)
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VALUES(10,'ACCOUNTING','NEW YORK');
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INSERT INTO dept_xwbing(deptno,dname,loc)
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VALUES(20,'RESEARCH','DALLAS');
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INSERT INTO dept_xwbing(deptno,dname,loc)
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VALUES(30,'SALES','CHICAGO');
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INSERT INTO dept_xwbing(deptno,dname,loc)
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VALUES(40,'OPERATIONS','BOSTON');
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select *from dept_xwbing;
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create table name2 (
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deptno NUMBER(2,0),
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dname VARCHAR2(14 BYTE),
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loc VARCHAR2(13 BYTE)
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);
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INSERT INTO name2(deptno,dname,loc)
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VALUES(10,'ACCOUNTING','NEW YORK');
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INSERT INTO name2(deptno,dname,loc)
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VALUES(20,'RESEARCH','DALLAS');
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INSERT INTO name2(deptno,dname,loc)
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VALUES(30,'SALES','CHICAGO');
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SELECT *FROM name4;
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alter table name2 modify(deptno NUMBER(4,0),
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dname VARCHAR2(14 BYTE))
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