【发布时间】:2020-04-17 04:51:52
【问题描述】:
我创建了一个从 2 个表中删除的删除连接,但目前它只匹配并删除其中一个连接表中的第一条记录:
delete srid, rid from sub_region as srid
join statistics s
on srid.sub_region_id = s.sub_region_id
join region as rid
on rid.region_id = s.region_id
where s.region_id = 1;
region table:
id, region
1 america
2 mexico
3 canada
sub_region table:
id, sub_region
1 texas
2 new york
statistics table:
id, region_id, sub_region_id, text_description
1 1 1 texas has pretty good bbq
2 1 2 new york is a concrete jungle
我的查询将: 1)删除统计表中的两条记录(因为我在 region 和 sub_region 上有一个外键,删除时级联) 2) 从与 region_id 匹配的区域表中删除区域 3) 只从 sub_region 表中删除 1 条记录
如果再次匹配统计表中的 region_id,我需要查询删除所有 sub_regions。
任何想法表示赞赏。
SQL:
-- -----------------------------------------------------
-- Table `region`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `region` (
`region_id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`region` VARCHAR(255) NULL,
PRIMARY KEY (`region_id`),
UNIQUE INDEX `region_id_UNIQUE` (`region_id` ASC) VISIBLE,
UNIQUE INDEX `region_UNIQUE` (`region` ASC) VISIBLE)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `sub_region`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `sub_region` (
`sub_region_id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`sub_region` VARCHAR(255) NULL,
PRIMARY KEY (`sub_region_id`),
UNIQUE INDEX `sub_region_id_UNIQUE` (`sub_region_id` ASC) VISIBLE,
UNIQUE INDEX `sub_region_UNIQUE` (`sub_region` ASC) VISIBLE)
ENGINE = InnoDB;
-- -----------------------------------------------------
-- Table `statistics`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `statistics` (
`statistics_id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`region_id` INT UNSIGNED NULL,
`sub_region_id` INT UNSIGNED NULL,
`text_description` VARCHAR(255) NULL,
PRIMARY KEY (`statistics_id`),
UNIQUE INDEX `statistics_id_UNIQUE` (`statistics_id` ASC) VISIBLE,
INDEX `fk_region_statistics_idx` (`region_id` ASC) VISIBLE,
INDEX `fk_sub_region_statistics_idx` (`sub_region_id` ASC) VISIBLE,
CONSTRAINT `fk_region_statistics`
FOREIGN KEY (`region_id`)
REFERENCES `region` (`region_id`)
ON DELETE CASCADE
ON UPDATE NO ACTION,
CONSTRAINT `fk_sub_region_statistics`
FOREIGN KEY (`sub_region_id`)
REFERENCES `sub_region` (`sub_region_id`)
ON DELETE CASCADE
ON UPDATE NO ACTION)
ENGINE = InnoDB;
【问题讨论】:
-
请将表格形式的源数据替换为他们的 CREATE TABLE + INSERT INTO 脚本。并显示所需的最终数据状态。
-
@Akina 添加 sql 创建表
-
只是为了观察这些有时被称为国家和州/省