-- 創建EMP表

CREATE TABLE EMP

(

EMPNO int(4) PRIMARY KEY,

ENAME VARCHAR(10),

JOB VARCHAR(9),

MGR INT(4),

HIREDATE DATE,

SAL DOUBLE(7,2),

COMM DOUBLE(7,2),

DEPTNO INT(2)

);

-- where查詢 語句

SELECT * from emp;

-- 模糊查詢

-- 搜索emp表中還有A的員工信息

SELECT * FROM emp where ENAME like '%A%';

-- 匹配ename中用A開頭的員工信息

SELECT * FROM emp where ENAME like 'A%';

-- 匹配ename中用A結尾的的員工信息

SELECT * FROM emp where ENAME like '%A';

-- 匹配ename中第二個字符為A的的員工信息

SELECT * FROM emp where ENAME like '_A%';

-- is null 判斷是否為空

-- 查詢所有沒有加班費的員工信息

SELECT * from emp where COMM is null;

SELECT * from emp where COMM is not null;

-- 小括號，增強可閱讀性

SELECT * FROM emp where ENAME='WARD' OR ENAME='ALLEN' AND SAL>7500;

SELECT * FROM emp where ENAME='WARD' OR (ENAME='ALLEN' AND SAL>7500);

?