在Mysql數(shù)據(jù)庫(kù)中，多張表之間的數(shù)據(jù)通常是相互關(guān)聯(lián)的。這些關(guān)聯(lián)有助于實(shí)現(xiàn)復(fù)雜的數(shù)據(jù)查詢和數(shù)據(jù)處理，因此需要建立這些表之間的連接。下面將介紹如何在Mysql中建立五個(gè)表的連接。

CREATE TABLE `employee` (
`id` int NOT NULL AUTO_INCREMENT,
`name` varchar(50) NOT NULL,
`department_id` int NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `department` (
`id` int NOT NULL AUTO_INCREMENT,
`name` varchar(50) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `task` (
`id` int NOT NULL AUTO_INCREMENT,
`name` varchar(50) NOT NULL,
`employee_id` int NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `attendance` (
`id` int NOT NULL AUTO_INCREMENT,
`employee_id` int NOT NULL,
`punch_time` datetime NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `salary` (
`id` int NOT NULL AUTO_INCREMENT,
`employee_id` int NOT NULL,
`salary` double NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

以上代碼創(chuàng)建了五個(gè)表：employee（員工表）、department（部門表）、task（任務(wù)表）、attendance（考勤表）、salary（薪資表）。

接下來(lái)，我們將通過(guò)使用外鍵將這些表連接起來(lái)。每個(gè)表都有一個(gè)主鍵，通過(guò)主鍵來(lái)建立連接。

ALTER TABLE `employee` ADD CONSTRAINT `employee_department_fk`
FOREIGN KEY (`department_id`) REFERENCES `department` (`id`)
ON DELETE RESTRICT
ON UPDATE CASCADE;
ALTER TABLE `task` ADD CONSTRAINT `task_employee_fk`
FOREIGN KEY (`employee_id`) REFERENCES `employee` (`id`)
ON DELETE RESTRICT
ON UPDATE CASCADE;
ALTER TABLE `attendance` ADD CONSTRAINT `attendance_employee_fk`
FOREIGN KEY (`employee_id`) REFERENCES `employee` (`id`)
ON DELETE CASCADE
ON UPDATE CASCADE;
ALTER TABLE `salary` ADD CONSTRAINT `salary_employee_fk`
FOREIGN KEY (`employee_id`) REFERENCES `employee` (`id`)
ON DELETE CASCADE
ON UPDATE CASCADE;

以上代碼將建立employee表與department表的連接，task表與employee表的連接，attendance表與employee表的連接，以及salary表與employee表的連接。這些連接將會(huì)在刪除或更新數(shù)據(jù)時(shí)起到作用。

通過(guò)以上操作，五個(gè)表之間的連接成功建立，便可以對(duì)這些表進(jìn)行復(fù)雜的數(shù)據(jù)處理和查詢。