技術標籤：MySQLmysql關聯查詢

MySQL關聯查詢

• 注意：
  • MySQL對大小寫不敏感
  • Oracle對大小寫敏感（預設大寫）
    • 字串使用單引號
• MySQL關聯查詢
  • 內連線
  • 左外連線
  • 右外連線
  • 全外連線（不支援）
  • 自然連線

--MYSQL
CREATE DATABASE mydb_2;
use mydb_2;

CREATE TABLE employee(
	`id` INT,
	`name` VARCHAR(32),
    `depid` INT
);
INSERT INTO employee VALUES(10001,"xiaoA",1);
INSERT INTO employee VALUES
 
(10002,"xiaoB",2);
INSERT INTO employee VALUES(10003,"xiaoC",3);
INSERT INTO employee VALUES(10004,"xiaoD",NULL);
CREATETABLEdep(
    `id` INT,
	`depname` VARCHAR(32)
);
INSERTINTOdepVALUES(1,"軟體開發部")5,(2,"軟體測試部"),(3,"人力資源部"),(4,"財務管理部");
--INNER JOIN...ON...
 

SELECT * FROM employee e INNER JOIN dep d ON e.depid=d.id;
--LEFT OUTER JOIN...ON...
SELECT * FROM employee e LEFT OUTER JOIN dep d ON e.depid=d.id;
--RIGHT OUTER JOIN...ON...
SELECT * FROM employee e RIGHT OUTER JOIN dep d ON e.depid=d.id;
--FULL OUTER JOIN(MySQL中沒有全外連線，但是可以使用UNION結合左右外連線)
SELECT *
 
 FROM employee e LEFT OUTER JOIN dep d ON e.depid=d.id
UNION
SELECT * FROM employee e RIGHT OUTER JOIN dep d ON e.depid=d.id;
--NATURAL JOIN
--自動根據兩表相同欄位進行連線
ALTER TABLE dep CHANGE id depid INT;
SELECT * FROM employee NATURAL JOIN dep;