Oracle SQL基础练习【二】（emp，dept）

一 创建表并插入数据

CREATE TABLE emp
(
empno    NUMBER,
ename    VARCHAR2(20),
job      VARCHAR2(20),
mgr      NUMBER,
hiredate DATE,
sal FLOAT,
commn FLOAT,
deptno NUMBER
);
INSERT
INTO emp
(
empno,
ename,
job,
mgr,
hiredate,
sal,
commn,
deptno
)
VALUES
(
1601,
'zhangsan',
'saler',
10,
to_date('2013-2-28 15:42:56','yyyy-mm-dd hh24:mi:ss'),
2000.1,
1000.3,
100
);

雇员表emp如下：

CREATE TABLE dept
( deptno NUMBER, dname VARCHAR2(30), loc VARCHAR2(50)
);

部门表emp如下：



二 操作表

1 基础查询

SELECT*FROM emp;

SELECT empno eno FROM emp;

SELECT DISTINCT job FROM emp;

SELECT job FROM emp;

SELECT 'NO:'||empno||',Name:'||ename||
',Job:'||job FROM emp;

2 添加 主键

ALTER TABLE emp ADD PRIMARY KEY(empno);

ALTER TABLE dept ADD PRIMARY KEY(deptno);

3 IS NOT NULL 和 BETWEEN AND

SELECT * FROM emp WHERE commn IS NOT NULL;

SELECT * FROM emp WHERE sal > 1500 AND commn IS NOT NULL;

SELECT * FROM emp WHERE sal <= 1500 AND commn IS NULL;

SELECT * FROM emp WHERE NOT(sal > 1500 AND commn IS NOT NULL);

SELECT * FROM emp WHERE hiredate BETWEEN '11-01-01' AND '11-12-31';

SELECT * FROM emp WHERE empno NOT IN(1601,1603);

4 oracle对字符串的大小写敏感

SELECT * FROM emp WHERE ename = 'Liulu';

SELECT * FROM emp WHERE ename = 'liulu';

5 LIKE，ASC，DESC

SELECT * FROM emp WHERE hiredate LIKE '%11%';
SELECT * FROM emp WHERE hiredate LIKE '_1%';

SELECT * FROM emp WHERE empno <> 1603;
SELECT * FROM emp WHERE empno != 1603;

SELECT * FROM emp ORDER BY sal ASC;
SELECT * FROM emp ORDER BY sal DESC;

SELECT * FROM emp ORDER BY sal DESC, empno ASC;

6 大小写

SELECT UPPER('jone') FROM dual;
SELECT LOWER('JONE') FROM dual;

SELECT INITCAP(ename) FROM emp;
UPDATE emp SET ename = INITCAP(ename);

UPDATE emp SET ename = 'stu_'||ename;
UPDATE emp SET ename = CONCAT('tu_',ename);

7 oracle中字符串截取从0和1开始都是一样的

SELECT SUBSTR('ABCDEFG',0,4),
LENGTH('CANDIDE'),
REPLACE('JACK and JUE','J','BL')
FROM dual;

SELECT SUBSTR('ABCDEFG',1,4),
LENGTH('CANDIDE'),
REPLACE('JACK and JUE','J','BL')
FROM dual;

8 小插曲1
创建表

CREATE TABLE table_1
( deptno NUMBER, empno NUMBER
);
CREATE TABLE table_2
( empno NUMBER, goods_name VARCHAR2(40)
);

表如下：





插入数据

INSERT INTO table_1(deptno,empno) VALUES(1,001);
INSERT INTO table_1(deptno,empno) VALUES(1,002);
INSERT INTO table_1(deptno,empno) VALUES(2,003);
INSERT INTO table_1(deptno,empno) VALUES(3,004);
INSERT INTO table_1(deptno,empno) VALUES(3,005);

INSERT INTO table_2(empno,goods_name) VALUES(001,'A');
INSERT INTO table_2(empno,goods_name) VALUES(002,'D');
INSERT INTO table_2(empno,goods_name) VALUES(001,'B');
INSERT INTO table_2(empno,goods_name) VALUES(001,'C');
INSERT INTO table_2(empno,goods_name) VALUES(003,'A');
INSERT INTO table_2(empno,goods_name) VALUES(004,'C');
INSERT INTO table_2(empno,goods_name) VALUES(005,'D');
INSERT INTO table_2(empno,goods_name) VALUES(004,'W');

基本操作

SELECT deptno,goods_name
FROM table_1 t1 JOIN table_2 t2
ON t1.empno = t2.empno
ORDER BY t1.deptno;

SELECT deptno,CO
4000
UNT(*) as goods
FROM table_1 t1 JOIN table_2 t2
ON t1.empno = t2.empno
GROUP BY deptno;

SELECT deptno,COUNT(*) as goods
FROM table_1 t1,table_2 t2
WHERE t1.empno = t2.empno
GROUP BY deptno;

9 小插曲2

VARCHAR2(50)必须指明长度

CREATE TABLE store (
storeno NUMBER
,start_date VARCHAR2(50)
,store_name VARCHAR2(50)
,over_date VARCHAR2(50)
);

ALTER TABLE store MODIFY (storeno VARCHAR2(50));

INSERT INTO store(
storeno
,start_date
,store_name
,over_date)
VALUES(
'C001'
,'2015/1/1'
,'7-11'
,'2099/12/31'
);
INSERT INTO store(
storeno
,start_date
,store_name
,over_date)
VALUES(
'C001'
,'2016/10/1'
,'8-13'
,'2099/12/31'
);
INSERT INTO store(
storeno
,start_date
,store_name
,over_date)
VALUES(
'C003'
,'2015/1/1'
,'JingGong'
,'2099/12/31'
);

表如下：



查询操作：

SELECT s1.storeno,s1.store_name
FROM store s1,
(SELECT storeno,MAX(start_date) AS start_date
FROM store
WHERE start_date <= TO_DATE('2016011','YYYYMMDD')
AND over_date >= TO_DATE('2016011','YYYYMMDD')
GROUP BY storeno) s2
WHERE s1.storeno = s2.storeno
AND s1.start_date = s2.start_date;

上下对比

SELECT s1.storeno,s1.store_name
FROM store s1,
(SELECT storeno,MAX(start_date) AS start_date
FROM store
WHERE start_date <= '20160101'
AND over_date >= '20160101'
GROUP BY storeno) s2
WHERE s1.storeno = s2.storeno
AND s1.start_date = s2.start_date;

修改字段数据类型

ALTER TABLE store MODIFY(start_date DATE);
ALTER TABLE store MODIFY(over_date DATE);

注意：

日期格式数据转换：TO_DATE(),TO_CHAR()

char,varchar,varchar2区别：

char长度固定，varchar只半字和全角字符2字处理，varchar2对所有都2字节处理