问题：

中秋提前下班，说数据库函数无法创建。数据库没的说，指定用户指定ip访问指定数据库全部权限。

。。。。。。

排查一下，发现数据库函数功能没有打开。函数这个问题吧，其实自己手动开启就行，比较简单。

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

1、查看数据库函数功能是否开启：

mysql> show variables like ‘%func%‘;

+---------------------------------+-------+

| Variable_name                   | Value |

+---------------------------------+-------+

| log_bin_trust_function_creators | OFF   |

+---------------------------------+-------+

1 row in set (0.00 sec)

注意：OFF，说明并没有开启；

mysql>

2、开启和关闭函数功能：

开启：

SET GLOBAL log_bin_trust_function_creators=1;

mysql> SET GLOBAL log_bin_trust_function_creators=1;

Query OK, 0 rows affected (0.00 sec)

mysql> show variables like ‘%func%‘;

+---------------------------------+-------+

| Variable_name                   | Value |

+---------------------------------+-------+

| log_bin_trust_function_creators | ON    |

+---------------------------------+-------+

1 row in set (0.00 sec)

mysql>

关闭：

SET GLOBAL log_bin_trust_function_creators=0;

问题：

上面命令行修改只是临时生效，数据库重启后仍然失效。

永久解决方案：

windows下my.ini

[mysqld]加上log_bin_trust_function_creators=1  

linux下/etc/my.cnf下my.cnf

[mysqld]加上log_bin_trust_function_creators=1

保存 ，重启服务器。

# service mysqld restart

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

3、谈谈命令行函数如何创建：（用工具的话指定简单许多）

查看数据库中所有的函数：

mysql> SHOW FUNCTION STATUS;

Empty set (0.00 sec)

mysql>

语法：（尊重原创，摘自：）

http://blog.csdn.net/jssg_tzw/article/details/39694489

CREATE FUNCTION func_name ( [func_parameter] ) //括号是必须的，参数是可选的  

RETURNS type  

[ characteristic ...] routine_body  

CREATE FUNCTION 用来创建函数的关键字；

func_name 表示函数的名称；

func_parameters为函数的参数列表，参数列表的形式为：[IN|OUT|INOUT] param_name type

IN：表示输入参数；

OUT：表示输出参数；

INOUT：表示既可以输入也可以输出；

param_name：表示参数的名称；

type：表示参数的类型，该类型可以是MySQL数据库中的任意类型；

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，取值与存储过程时相同，详细请访问－MySQL存储过程使用;

eg：

mysql> create database hr;  

Query OK, 1 row affected (0.00 sec)

mysql> use hr;  

Database changed

mysql> 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)  

    -> ); 

Query OK, 0 rows affected (1.17 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘David Tian‘,‘男‘,10,7500,1);  

‘,‘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) valuesQuery OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Black Xie‘,‘男‘,10,6600,1);  

Query OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Moses Wang‘,‘男‘,10,4300,1);  

Query OK, 1 row affected (0.03 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Rena Ruan‘,‘女‘,10,5300,1);  

Query OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Sunshine Ma‘,‘女‘,10,6500,2);  

Query OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Scott Gao‘,‘男‘,10,9500,2);  

Query OK, 1 row affected (0.01 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Warren Si‘,‘男‘,10,7800,2);  

Query OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Kaishen Yang‘,‘男‘,10,9500,3);  

Query OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Simon Song‘,‘男‘,10,5500,3);  

Query OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Brown Guan‘,‘男‘,10,5000,3);  

Query OK, 1 row affected (0.01 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Eleven Chen‘,‘女‘,10,3500,2);  

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,eQuery OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Cherry Zhou‘,‘女‘,10,5500,4);  

Query OK, 1 row affected (0.01 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Klause He‘,‘男‘,10,4500,5);  

mployee_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,eQuery OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Maven Ma‘,‘男‘,10,4500,6);  

Query OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Stephani Wang‘,‘女‘,10,5500,7);  

Query OK, 1 row affected (0.01 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Jerry Guo‘,‘男‘,10,8500,1);  

Query OK, 1 row affected (0.00 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Gerardo Garza‘,‘男‘,10,25000,8);  

Query OK, 1 row affected (0.01 sec)

mysql> insert into employees(employee_name,employee_sex,employee_mgr,employee_salary,department_id) values (‘Derek Wu‘,‘男‘,10,5500,5);  

Query OK, 1 row affected (0.03 sec)

mysql> select * from employees; 

+-------------+---------------+--------------+---------------------+--------------+-----------------+---------------+

| employee_id | employee_name | employee_sex | hire_date           | employee_mgr | employee_salary | department_id |

+-------------+---------------+--------------+---------------------+--------------+-----------------+---------------+

|           1 | David Tian    | 男           | 2016-06-03 13:50:28 |           10 |            7500 |             1 |

|           2 | Black Xie     | 男           | 2016-06-03 13:50:28 |           10 |            6600 |             1 |

|           3 | Moses Wang    | 男           | 2016-06-03 13:50:28 |           10 |            4300 |             1 |

|           4 | Rena Ruan     | 女           | 2016-06-03 13:50:28 |           10 |            5300 |             1 |

|           5 | Sunshine Ma   | 女           | 2016-06-03 13:50:28 |           10 |            6500 |             2 |

|           6 | Scott Gao     | 男           | 2016-06-03 13:50:28 |           10 |            9500 |             2 |

|           7 | Warren Si     | 男           | 2016-06-03 13:50:28 |           10 |            7800 |             2 |

|           8 | Kaishen Yang  | 男           | 2016-06-03 13:50:28 |           10 |            9500 |             3 |

|           9 | Simon Song    | 男           | 2016-06-03 13:50:28 |           10 |            5500 |             3 |

|          10 | Brown Guan    | 男           | 2016-06-03 13:50:28 |           10 |            5000 |             3 |

|          11 | Eleven Chen   | 女           | 2016-06-03 13:50:28 |           10 |            3500 |             2 |

|          12 | Cherry Zhou   | 女           | 2016-06-03 13:50:28 |           10 |            5500 |             4 |

|          13 | Klause He     | 男           | 2016-06-03 13:50:28 |           10 |            4500 |             5 |

|          14 | Maven Ma      | 男           | 2016-06-03 13:50:28 |           10 |            4500 |             6 |

|          15 | Stephani Wang | 女           | 2016-06-03 13:50:28 |           10 |            5500 |             7 |

|          16 | Jerry Guo     | 男           | 2016-06-03 13:50:28 |           10 |            8500 |             1 |

|          17 | Gerardo Garza | 男           | 2016-06-03 13:50:28 |           10 |           25000 |             8 |

|          18 | Derek Wu      | 男           | 2016-06-03 13:50:32 |           10 |            5500 |             5 |

+-------------+---------------+--------------+---------------------+--------------+-----------------+---------------+

18 rows in set (0.00 sec)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

创建函数－根据ID获取员工姓名与员工工资

mysql> DELIMITER //  

mysql> 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//  

Query OK, 0 rows affected (0.00 sec)

查看：

mysql> select GetEmployeeInformationByID(1);

+-----------------------------------------+

| GetEmployeeInformationByID(1)           |

+-----------------------------------------+

| employee name:David Tian---salary: 7500 |

+-----------------------------------------+

1 row in set (0.00 sec)

mysql>

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谈谈MySQL的函数问题！