Mysql在删除集null上创建具有多个外键的表

我正试图创建一个包含多个外键且具有删除/更新约束的数据库，但在以下sql脚本中出现错误代码1005：

CREATE TABLE Worker (
 WorkerID smallint auto_increment,
 WorkerType  varchar(45) NOT NULL,
 WorkerName  varchar(45) NOT NULL,
 Position    varchar(45) NOT NULL,
 TaxFileNumber int NOT NULL,
 Address    varchar(100) ,
 Phone      varchar(20) ,
 SupervisorID  smallint ,
 PRIMARY KEY (WorkerID),
 FOREIGN KEY (SupervisorID) REFERENCES Worker(WorkerID)
    ON DELETE SET NULL
    ON UPDATE CASCADE
)Engine=InnoDB;

CREATE TABLE Grape (
    GrapeID smallint NOT NULL,
    GrapeType varchar(45) NOT NULL,
    JuiceConversionRatio int,
    StorageContainer ENUM('Stainless Steel Tank','Oak Barrel'),
    AgingRequirement int,
    PRIMARY KEY (GrapeID)
)Engine=InnoDB;

CREATE TABLE Vineyard (
    VineyardID smallint auto_increment,
    VineyardName VARCHAR(45) NOT NULL,
    FarmerID    smallint NOT NULL,
    GrapeID smallint NOT NULL,
    ComeFrom    varchar(45) NOT NULL,
    HarvestedAmount int,
    RipenessPercent int,
    PRIMARY KEY (VineyardID),
    FOREIGN KEY (FarmerID) REFERENCES Worker(WorkerID)
        ON DELETE SET NULL
        ON UPDATE CASCADE,
    FOREIGN KEY (GrapeID) REFERENCES Grape(GrapeID)
        ON DELETE SET NULL
        ON UPDATE CASCADE
)Engine=InnoDB;

---

错误代码表示无法创建Vineyard表，我只想知道使用delete/update控件创建多个外键的正确格式。

您的外键规则是删除集NULL时的

，但列定义是
非NULL

更改列定义并删除
notnull
部分，或者过度考虑外键规则。这是有效的：

CREATE TABLE Vineyard (
    VineyardID smallint auto_increment,
    VineyardName VARCHAR(45) NOT NULL,
    FarmerID    smallint,
    GrapeID smallint,
    ComeFrom    varchar(45) NOT NULL,
    HarvestedAmount int,
    RipenessPercent int,
    PRIMARY KEY (VineyardID),
    FOREIGN KEY (FarmerID) REFERENCES Worker(WorkerID)
        ON DELETE SET NULL
        ON UPDATE CASCADE,
    FOREIGN KEY (GrapeID) REFERENCES Grape(GrapeID)
        ON DELETE SET NULL
        ON UPDATE CASCADE
)Engine=InnoDB;

访问：


尝试使用不带外键的create table（
innoDB enginer
）并使用
update table with constraint
语法，例如：

ALTER TABLE `vineyard`
        ADD CONSTRAINT `relation_farmer_has_many_vineyards`
            FOREIGN KEY (`farmer_id`)
            REFERENCES `worker` (`worker_id`)
            ON DELETE SET NULL
            ON UPDATE CASCADE;

参考资料：




技巧：不建议在行为与所用操作系统不同的表的名称中使用大写字母（或驼峰大小写）：




访问：


ALTER TABLE `vineyard`
        ADD CONSTRAINT `relation_farmer_has_many_vineyards`
            FOREIGN KEY (`farmer_id`)
            REFERENCES `worker` (`worker_id`)
            ON DELETE SET NULL
            ON UPDATE CASCADE;

Cursor c = db.query(
    FeedEntry.TABLE_NAME,                     // The table to query
    projection,                               // The columns to return
    selection,                                // The columns for the WHERE clause
    selectionArgs,                            // The values for the WHERE clause
    null,                                     // don't group the rows
    null,                                     // don't filter by row groups
    sortOrder                                 // The sort order
    );