解决 MySQL 中的错误 1111 (HY000):在组函数中使用无效?如何正确与 where 子句结合使用聚合函数?
若要在 MySQL 中正确地与 where 子句结合使用聚合函数,语法如下 −
select *from yourTableName where yourColumnName > (select AVG(yourColumnName) from yourTableName);
为了理解上述概念,让我们创建一个表格。创建表格的查询如下 −
mysql> create table EmployeeInformation -> ( -> EmployeeId int, -> EmployeeName varchar(20), -> EmployeeSalary int, -> EmployeeDateOfBirth datetime -> ); Query OK, 0 rows affected (1.08 sec)
现在,可以使用 insert 命令在表格中插入一些记录。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 语句显示表格中的所有记录。查询如下 −
mysql> select *from EmployeeInformation;
输出如下 −
+------------+--------------+----------------+---------------------+ | 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)
以下是与 where 子句结合使用聚合的正确方式。查询如下 −
mysql> select *from EmployeeInformation -> where EmployeeSalary > (select AVG(EmployeeSalary) from EmployeeInformation);
输出如下 −
+------------+--------------+----------------+---------------------+ | EmployeeId | EmployeeName | EmployeeSalary | EmployeeDateOfBirth | +------------+--------------+----------------+---------------------+ | 105 | Bob | 7500 | 1993-11-26 00:00:00 | +------------+--------------+----------------+---------------------+ 1 row in set (0.04 sec)
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