解决错误 1111 (HY000):MySQL 中组函数的使用无效?如何正确使用带有 where 子句的聚合函数?
mysqlmysqli database
要在 MySQL 中正确使用带有 where 子句的聚合函数，以下是语法 −
select *from yourTableName where yourColumnName > (select AVG(yourColumnName) from yourTableName);
为了理解上述概念，让我们创建一个表。创建表的查询如下 −
mysql> create table EmployeeInformation -> ( -> EmployeeId int, -> EmployeeName varchar(20), -> EmployeeSalary int, -> EmployeeDateOfBirth datetime -> ); Query OK, 0 rows affected (1.08 sec)
现在，您可以使用 insert 命令在表中插入一些记录。查询如下 −
mysql> insert into EmployeeInformation values(101,'John',5510,'1995-01-21'); Query OK, 1 row affected (0.13 sec) mysql> insert into EmployeeInformation values(102,'Carol',5600,'1992-03-25'); Query OK, 1 row affected (0.56 sec) mysql> insert into EmployeeInformation values(103,'Mike',5680,'1991-12-25'); Query OK, 1 row affected (0.14 sec) mysql> insert into EmployeeInformation values(104,'David',6000,'1991-12-25'); Query OK, 1 row affected (0.23 sec) mysql> insert into EmployeeInformation values(105,'Bob',7500,'1993-11-26'); Query OK, 1 row affected (0.16 sec)
使用 select 语句显示表中的所有记录。查询如下 −
mysql> select *from EmployeeInformation;
以下是输出 −
+------------+--------------+----------------+---------------------+ | EmployeeId | EmployeeName | EmployeeSalary | EmployeeDateOfBirth | +------------+--------------+----------------+---------------------+ | 101 | John | 5510 | 1995-01-21 00:00:00 | | 102 | Carol | 5600 | 1992-03-25 00:00:00 | | 103 | Mike | 5680 | 1991-12-25 00:00:00 | | 104 | David | 6000 | 1991-12-25 00:00:00 | | 105 | Bob | 7500 | 1993-11-26 00:00:00 | +------------+--------------+----------------+---------------------+ 5 rows in set (0.00 sec)
这是使用带有 where 子句的聚合的正确方法。查询如下 −
mysql> select *from EmployeeInformation -> where EmployeeSalary > (select AVG(EmployeeSalary) from EmployeeInformation);
以下是输出 −
+------------+--------------+----------------+---------------------+ | EmployeeId | EmployeeName | EmployeeSalary | EmployeeDateOfBirth | +------------+--------------+----------------+---------------------+ | 105 | Bob | 7500 | 1993-11-26 00:00:00 | +------------+--------------+----------------+---------------------+ 1 row in set (0.04 sec)
