目标
怎么样MySQL创建数据库功能(Function)
语法
CREATE FUNCTION func_name ( [func_parameter] ) //括号是必须的,參数是可选的
RETURNS type
[ characteristic ...] routine_body
- CREATE FUNCTION 用来创建函数的keyword;
- func_name 表示函数的名称;
- func_parameters为函数的參数列表,參数列表的形式为:[IN|OUT|INOUT] param_name type
- IN:表示输入參数。
- OUT:表示输出參数;
- INOUT:表示既能够输入也能够输出;
- param_name:表示參数的名称;
- type:表示參数的类型,该类型能够是MySQL数据库中的随意类型;
- RETURNS type:语句表示函数返回数据的类型;
- characteristic: 指定存储函数的特性,取值与存储过程时同样,具体请訪问-MySQL存储过程使用;
演示样例
创建演示样例数据库、演示样例表与插入样例数据脚本:
create database hr;
use hr;
create table employees
(
employee_id int(11) primary key not null auto_increment,
employee_name varchar(50) not null,
employee_sex varchar(10) default '男',
hire_date datetime not null default current_timestamp,
employee_mgr int(11),
employee_salary float default 3000,
department_id int(11)
);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('David Tian','男',10,7500,1);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Black Xie','男',10,6600,1);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Moses Wang','男',10,4300,1);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Rena Ruan','女',10,5300,1);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Sunshine Ma','女',10,6500,2);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Scott Gao','男',10,9500,2);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Warren Si','男',10,7800,2);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Kaishen Yang','男',10,9500,3);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Simon Song','男',10,5500,3);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Brown Guan','男',10,5000,3);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Eleven Chen','女',10,3500,2);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Cherry Zhou','女',10,5500,4);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Klause He','男',10,4500,5);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Maven Ma','男',10,4500,6);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Stephani Wang','女',10,5500,7);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Jerry Guo','男',10,8500,1);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Gerardo Garza','男',10,25000,8);
insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values ('Derek Wu','男',10,5500,5);
select * from employees;
![](http://img.e-com-net.com/image/info8/0176f667ee1b4f35833202d404d49012.png)
创建函数-依据ID获取员工姓名与员工工资
DELIMITER //
CREATE FUNCTION GetEmployeeInformationByID(id INT)
RETURNS VARCHAR(300)
BEGIN
RETURN(SELECT CONCAT('employee name:',employee_name,'---','salary: ',employee_salary) FROM employees WHERE employee_id=id);
END//
DELIMITER ;
调用函数
在MySQL——函数的用法与MySQL内部函数的用法一样。
<很多其它精彩内容。见后面更新...>
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