SELECT empno,ename,job,mgr,sal,comm,deptno FROM emp; 创建一个emp

上述SQL语句是用来从名为"emp"的员工表中选择特定列的数据。具体来说，它会选择以下几项内容：

- `empno`: 员工编号
- `ename`: 员工姓名
- `job`: 岗位
- `mgr`: 管理员ID（可能是上级员工的编号）
- `sal`: 工资
- `comm`: 委托奖金
- `deptno`: 部门编号

这是一条标准的SELECT语句，用于数据检索，如果将此查询运行在一个数据库上，它将返回对应表中这些列的所有记录。

创建一个类似"emp"的表，可以用以下SQL命令（假设我们正在使用Oracle数据库为例）:

CREATE TABLE emp (
    empno NUMBER PRIMARY KEY,    -- 员工编号
    ename VARCHAR(50),         -- 姓名
    job VARCHAR(15),           -- 岗位
    mgr NUMBER,                -- 上级管理者
    sal NUMBER,                -- 工资
    comm NUMBER,               -- 委托奖金
    deptno NUMBER             -- 部门编号
);

这条命令会创建一个新的表，并定义了各个字段的数据类型和主键约束。

相关问题

EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO 7369 SMITH CLERK 7902 17-DEC-80 800 NULL 20 7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30 7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30 7565 EMILY SALESMAN 7698 20-FEB-81 1250 800 30 7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30 7655 JONES MANAGER 7839 2-APR-81 2975 NULL 20 7698 BLAKE MANAGER 7839 1-MAY-91 2850 NULL 30 7782 CLARK MANAGER 7839 9-JUN-81 2450 NULL 10 7788 SCOTT ANALYST 7655 21-MAR-87 3000 NULL 20 7844 TURNER SALESMAN 7698 18-SEP-81 1500 NULL 30 7876 ADAMS CLERK 7788 24-APR-87 1100 NULL 20 7900 JAMES CLERK 7698 3-DEC-81 950 NULL 30 7902 FORD ANALYST 7655 3-DEC-81 3000 NULL 20 7934 MILLER CLERK 7782 3-JAN-81 1300 NULL 10 Given This Table Called 'EMP', please define a function that, given a department number, returns the average salary of that department.

Sure, here's the function in SQL:

CREATE FUNCTION avg_salary_dept (dept_no INT) RETURNS DECIMAL(10, 2)
BEGIN
    DECLARE total_salary DECIMAL(10, 2);
    DECLARE num_employees INT;
    SELECT SUM(sal) INTO total_salary, COUNT(*) INTO num_employees FROM EMP WHERE DEPTNO = dept_no;
    RETURN total_salary / num_employees;
END;

This function takes in a department number and returns the average salary of employees in that department. It uses the SQL `SUM` function to add up all the salaries of employees in the department, and the `COUNT` function to get the number of employees in the department. Then it calculates the average salary by dividing the total salary by the number of employees, and returns the result.

创建表emp,并插入 EMPNO、ENAME、JOB、MGR、HIREDATE、SAL、COMM 和 DEPTNO这些列

好的，以下是创建表emp并插入数据的SQL语句：

CREATE TABLE emp (
  EMPNO NUMBER(4) PRIMARY KEY,
  ENAME VARCHAR2(10),
  JOB VARCHAR2(9),
  MGR NUMBER(4),
  HIREDATE DATE,
  SAL NUMBER(7,2),
  COMM NUMBER(7,2),
  DEPTNO NUMBER(2)
);

INSERT INTO emp VALUES (7369, 'SMITH', 'CLERK', 7902, TO_DATE('1980-12-17', 'YYYY-MM-DD'), 800, NULL, 20);
INSERT INTO emp VALUES (7499, 'ALLEN', 'SALESMAN', 7698, TO_DATE('1981-02-20', 'YYYY-MM-DD'), 1600, 300, 30);
INSERT INTO emp VALUES (7521, 'WARD', 'SALESMAN', 7698, TO_DATE('1981-02-22', 'YYYY-MM-DD'), 1250, 500, 30);
INSERT INTO emp VALUES (7566, 'JONES', 'MANAGER', 7839, TO_DATE('1981-04-02', 'YYYY-MM-DD'), 2975, NULL, 20);
INSERT INTO emp VALUES (7654, 'MARTIN', 'SALESMAN', 7698, TO_DATE('1981-09-28', 'YYYY-MM-DD'), 1250, 1400, 30);
INSERT INTO emp VALUES (7698, 'BLAKE', 'MANAGER', 7839, TO_DATE('1981-05-01', 'YYYY-MM-DD'), 2850, NULL, 30);
INSERT INTO emp VALUES (7782, 'CLARK', 'MANAGER', 7839, TO_DATE('1981-06-09', 'YYYY-MM-DD'), 2450, NULL, 10);
INSERT INTO emp VALUES (7788, 'SCOTT', 'ANALYST', 7566, TO_DATE('1982-12-09', 'YYYY-MM-DD'), 3000, NULL, 20);
INSERT INTO emp VALUES (7839, 'KING', 'PRESIDENT', NULL, TO_DATE('1981-11-17', 'YYYY-MM-DD'), 5000, NULL, 10);
INSERT INTO emp VALUES (7844, 'TURNER', 'SALESMAN', 7698, TO_DATE('1981-09-08', 'YYYY-MM-DD'), 1500, 0, 30);
INSERT INTO emp VALUES (7876, 'ADAMS', 'CLERK', 7788, TO_DATE('1983-01-12', 'YYYY-MM-DD'), 1100, NULL, 20);
INSERT INTO emp VALUES (7900, 'JAMES', 'CLERK', 7698, TO_DATE('1981-12-03', 'YYYY-MM-DD'), 950, NULL, 30);
INSERT INTO emp VALUES (7902, 'FORD', 'ANALYST', 7566, TO_DATE('1981-12-03', 'YYYY-MM-DD'), 3000, NULL, 20);
INSERT INTO emp VALUES (7934, 'MILLER', 'CLERK', 7782, TO_DATE('1982-01-23', 'YYYY-MM-DD'), 1300, NULL, 10);

这个SQL语句会先创建一个名为emp的表，包含EMPNO、ENAME、JOB、MGR、HIREDATE、SAL、COMM和DEPTNO这些列，并将EMPNO列设为主键。然后，通过INSERT INTO语句向表中插入了一些数据。