資料結構
網路
RDBMS
作業系統
Java
MS Excel
iOS
HTML
CSS
安卓
Python
C 程式設計
C++
C#
MongoDB
MySQL
Javascript
PHP
物理
化學
生物
數學
英語
經濟
心理學
社會科學
時裝研究
法律研究在單個 MySQL 查詢中獲取兩個表字段的計數？
為此，你可以將 CASE 語句與 SUM() 一起使用。這裡，我們將查詢一列員工性別值中男性和女性記錄的計數。讓我們首先建立一個表 -
mysql> create table DemoTable
(
EmployeeGender ENUM('Male','Female')
);
Query OK, 0 rows affected (0.52 sec)使用 insert 命令在表中插入一些記錄 -
mysql> insert into DemoTable values('Male');
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable values('Female');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable values('Male');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable values('Female');
Query OK, 1 row affected (0.08 sec)
mysql> insert into DemoTable values('Male');
Query OK, 1 row affected (0.07 sec)
mysql> insert into DemoTable values('Female');
Query OK, 1 row affected (0.08 sec)使用 select 語句從表中顯示所有記錄 -
mysql> select *from DemoTable;
這將生成以下輸出 -
+----------------+ | EmployeeGender | +----------------+ | Male | | Female | | Male | | Female | | Male | | Female | +----------------+ 6 rows in set (0.00 sec)
以下是獲取一個查詢中兩個表字段計數的查詢 -
mysql> select sum(case when EmployeeGender='Male' then 1 else 0 end) as Total_Number_Of_Male_Employee, sum(case when EmployeeGender='Female' then 1 else 0 end) as Total_Number_Of_Female_Employee from DemoTable;
這將生成以下輸出 -
+-------------------------------+---------------------------------+ | Total_Number_Of_Male_Employee | Total_Number_Of_Female_Employee | +-------------------------------+---------------------------------+ | 3 | 3 | +-------------------------------+---------------------------------+ 1 row in set (0.00 sec
更新於：30-Sep-2019
597 次檢視
廣告