This is the SQL I used in LinqPad:
CREATE TABLE Category
(
catID int NOT NULL,
catName NVARCHAR(150) NOT NULL,
catDesc NVARCHAR(150) NULL,
catCount int NOT NULL ,
CONSTRAINT category_pk PRIMARY KEY (catID)
);
CREATE TABLE InventoryTBLC
(
itemID int NOT NULL IDENTITY(1,1) CONSTRAINT PK_items PRIMARY KEY,
itemName NVARCHAR(150) NOT NULL,
itemDesc NVARCHAR(150) NULL,
itemQuantity int,
itemPrice int,
imagePath NVARCHAR(300),
correctInsert NVARCHAR(300),
realImage image,
CONSTRAINT FK_category FOREIGN KEY (catID) REFERENCES Category(catID)
);
But I get the following error:
Invalid column ID. [ catID ]
Can someone help me with the LinqPad syntax?
If you want to use a column as the foreign key, you have to list that column in your table definition first! Adding the foreign key constraint does NOT add that column to your table!
And this is in no way Linqpad specific - this is standard SQL behavior.
So either you need to add catId to your second table like this:
CREATE TABLE InventoryTBLC
(
itemID int NOT NULL IDENTITY(1,1) CONSTRAINT PK_items PRIMARY KEY,
itemName NVARCHAR(150) NOT NULL,
itemDesc NVARCHAR(150) NULL,
itemQuantity int,
itemPrice int,
imagePath NVARCHAR(300),
correctInsert NVARCHAR(300),
realImage image,
catID int NOT NULL, -- this column *MUST* exist to be used as FK
CONSTRAINT FK_category
FOREIGN KEY (catID) REFERENCES Category(catID)
);
or then maybe you want to use one of the other pre-existing columns in InventoryTBLC as your FK column?
Related
CREATE TABLE student
(
student_id INT PRIMARY KEY,
first_name VARCHAR(40) NOT NULL,
last_name VARCHAR(40) NOT NULL,
birth_day DATE NOT NULL,
sex VARCHAR(1) NOT NULL,
student_email_address VARCHAR(40) NOT NULL UNIQUE,
student_password VARCHAR(10) NOT NULL UNIQUE,
student_nick_name VARCHAR(10) NOT NULL,
student_qualification VARCHAR(10) NOT NULL,
student_documents VARCHAR(255) NOT NULL,
student_image VARCHAR(100) NOT NULL
);
CREATE TABLE student_feedback
(
sr_no BIGSERIAL PRIMARY KEY,
student_id INT NOT NULL,
feedback_type VARCHAR(10) NOT NULL,
feedback_text VARCHAR(200) NOT NULL,
FOREIGN KEY (student_id) REFERENCES student(student_id)
);
CREATE TABLE online_exam
(
exam_id INT PRIMARY KEY,
exam_title VARCHAR(20) UNIQUE NOT NULL,
exam_duration_min INT NOT NULL,
total_questions INT NOT NULL,
marks_per_right_answer INT NOT NULL,
marks_per_wrong_answer INT NOT NULL,
passing_marks INT NOT NULL,
exam_status VARCHAR(2)
);
CREATE TABLE exam_subjects
(
sub_id INT,
exam_id INT,
sub_name VARCHAR(20) NOT NULL,
sub_desc VARCHAR(20) NOT NULL,
UNIQUE(sub_id,exam_id),
PRIMARY KEY(sub_id,exam_id),
FOREIGN KEY (exam_id) REFERENCES online_exam(exam_id) ON DELETE CASCADE
);
CREATE TABLE sub_questions
(
sub_id1 INT,
ques_id INT,
ques_text VARCHAR(150) NOT NULL,
ques_attachments VARCHAR(255),
option_1 VARCHAR(20) NOT NULL,
option_2 VARCHAR(20) NOT NULL,
option_3 VARCHAR(20) NOT NULL,
option_4 VARCHAR(20) NOT NULL,
UNIQUE(sub_id1,ques_id),
PRIMARY KEY (sub_id1,ques_id),
FOREIGN KEY (sub_id1) REFERENCES exam_subjects(sub_id) ON DELETE CASCADE
);
CREATE TABLE ques_answers
(
ans_id INT,
ques_id INT,
ans VARCHAR(20) NOT NULL,
PRIMARY KEY (ans_id,ques_id),
FOREIGN KEY (ques_id) REFERENCES sub_questions(ques_id) ON DELETE CASCADE
);
CREATE TABLE exam_registration
(
student_id INT,
exam_id INT,
exam_date_time TIMESTAMP NOT NULL,
PRIMARY KEY (student_id,exam_id),
FOREIGN KEY (student_id) REFERENCES student(student_id) ON DELETE CASCADE,
FOREIGN KEY (exam_id) REFERENCES online_exam(exam_id) ON DELETE CASCADE
);
CREATE TABLE exam_result
(
student_id INT,
exam_id INT,
sub_id INT,
marks_scored INT NOT NULL,
correct_ques INT NOT NULL,
wrong_ques INT NOT NULL,
grade VARCHAR(10) NOT NULL,
PRIMARY KEY(student_id,exam_id,sub_id),
FOREIGN KEY (student_id) REFERENCES student(student_id) ON DELETE CASCADE,
FOREIGN KEY (exam_id) REFERENCES online_exam(exam_id) ON DELETE CASCADE,
FOREIGN KEY (sub_id) REFERENCES exam_subjects(sub_id) ON DELETE CASCADE
);
Output :
CREATE TABLE,
CREATE TABLE,
CREATE TABLE,
CREATE TABLE,
There is no unique constraint matching given keys for referenced table "exam_subjects", relation "sub_questions" do not exist,
CREATE TABLE,
There is no unique constraint matching given keys for referenced table "exam_subjects".
Why am I getting "there is no unique..." error in postgresql? How to solve it? Please help.
In your table exam_subjects the primary key is a compossed key (PRIMARY KEY(sub_id, exam_id))
Therefore, your table sub_questions must have both columns to create the constraint, otherwise you get the error about unique constraints (or you can create a unique field acting as primary key, and create a unique index on both columns sub_id and exam_id)
create database shop1
use shop1
create table mathang
(
MatHangID INT primary key not null,
TenMatHang varchar(50),
SoLuong int not null,
Price int not null,
)
create table nhacungcap
(
MatHangID INT foreign key references mathang,
TenNhaCungCap varchar(50) ,
DiaChi varchar(100),
SoDienThoai int ,
CONSTRAINT pk_M_CC primary key (MatHangID)
)
create table khachhang
(
KhachHangID int not null primary key,
TenKhachHang varchar(50) not null,
[DiaChi] varchar(100) not null,
[SoDienThoai] varchar(50) not null,
)
create table donhang
(
DonHangID int references to khachhang(KhachHangID),
TenDonHang varchar(50),
SoLuong int,
CONSTRAINT pk_DHID primary key (DonHangID)
)
I can not find errors with this, it shows the foreign key error to add this relation ship. Any one please help.
Remove the to in
...
DonHangID int references to khachhang(KhachHangID)
...
to get
...
DonHangID int references khachhang(KhachHangID)
...
. The to doesn't belong there syntactically.
I'm trying to run this query but SQL -erver stopped me with this error:
Foreign key 'FK__food__groupid__3F115E1A' references invalid column 'groupid' in referenced table 'sub'.
This is my query:
create table menu
(
valedid int primary key not null,
name nvarchar(50) not null,
)
create table sub
(
qroupid int primary key not null,
groupname nvarchar(50) not null,
valedid int not null,
foreign key(valedid) references menu (valedid),
)
create table food
(
foodid int primary key not null,
radif int identity(1,1) not null,
qeymat int not null,
name nvarchar(100) not null,
groupid int not null,
foreign key(groupid) references sub(groupid),
)
You create the column with name qroupid and not groupid in table sub
Here is my code it generates Foreign key conflict error
CREATE TABLE tblProducts
(
ProductID int NOT NULL IDENTITY PRIMARY KEY,
ProductName nvarchar(30) NOT NULL,
BatchID int NOT NULL FOREIGN KEY REFERENCES tblBatches (BatchID)
)
CREATE TABLE tblBatches
(
BatchID INT NOT NULL IDENTITY PRIMARY KEY,
BatchCode nvarchar(20) NOT NULL,
Quantity int NOT NULL,
BatchMnf Date NOT NULL,
BatchExp Date NOT NULL,
PurchaseRate int NOT NULL,
SalesRate int NOT NULL,
ProductID int NOT NULL FOREIGN KEY REFERENCES tblProducts (ProductID)
)
You cannot do that. This is a circular reference.
This is a bad design but if you want to do that, you need to make foreign key columns Nullable.
CREATE TABLE tblProducts
(
ProductID int NOT NULL IDENTITY PRIMARY KEY,
ProductName nvarchar(30) NOT NULL,
BatchID int NULL FOREIGN KEY REFERENCES tblBatches (BatchID)
)
CREATE TABLE tblBatches
(
BatchID INT NOT NULL IDENTITY PRIMARY KEY,
BatchCode nvarchar(20) NOT NULL,
Quantity int NOT NULL,
BatchMnf Date NOT NULL,
BatchExp Date NOT NULL,
PurchaseRate int NOT NULL,
SalesRate int NOT NULL,
ProductID int NULL FOREIGN KEY REFERENCES tblProducts (ProductID)
)
Then you need to update reference fields after inserting records in tblBatches and tblProducts.
The good design says you need to create a bridge table like this:
CREATE TABLE tblProductsBatch
(
ID int NOT NULL IDENTITY PRIMARY KEY,
ProductID int NOT NULL,
BatchID int NOT NULL
)
And after inserting product and batch, you need to insert a record in this table to link rows to each other.
I have the following T-SQL schema. The problem I am having is that the check constraint on the Download table is not working. I am still able to insert records into that table that contain NULL values for both ProductId and CategoryId. Why is this so?
I want both the ProductId and CategoryId columns to allow NULL values, but for any given record only one of these are allowed to be set to NULL, the other needs to be a corresponding Id of the Category or Product table.
CREATE TABLE Category (
Id int IDENTITY(1,1) NOT NULL PRIMARY KEY,
Description nvarchar(100) NULL,
ParentCategoryId int NULL
CONSTRAINT fk_CategoryId_CategoryId FOREIGN KEY (Id) REFERENCES Category(Id)
)
GO
CREATE TABLE Product (
Id int IDENTITY(1,1) NOT NULL PRIMARY KEY,
Title nvarchar(100) NOT NULL,
TagLine nvarchar(MAX) NOT NULL,
Description nvarchar(MAX)NULL,
CategoryId int NOT NULL,
ImageUrl nvarchar(255) NULL,
Keywords nvarchar(200) NOT NULL
CONSTRAINT fk_ProductCategoryId_CategoryId FOREIGN KEY (CategoryId) REFERENCES Category(Id)
)
GO
CREATE TABLE Download (
Id int IDENTITY(1,1) NOT NULL PRIMARY KEY,
Title nvarchar(100) NOT NULL,
Description nvarchar(MAX) NULL,
CategoryId int NULL,
ProductId int NULL,
DownloadUrl nvarchar(255) NOT NULL,
CONSTRAINT fk_DownloadCategoryId FOREIGN KEY (CategoryId) REFERENCES Category(Id),
CONSTRAINT fk_DownloadProductId FOREIGN KEY (ProductId) REFERENCES Product(Id),
CONSTRAINT chk_ReferencesCategoryOrProduct CHECK (ProductID != NULL AND CategoryId != NULL)
)
GO
Use:
CONSTRAINT chk_ReferencesCategoryOrProduct CHECK (ProductID IS NOT NULL
OR CategoryId IS NOT NULL)
NULL isn't a value -- it's a placeholder for the lack of a value. Which is why you need to use specific syntax to check for it.