CREATE TABLE emp3(
id int(3) auto_increment,
first_name varchar(30) NOT NULL,
last_name varchar(30),
email varchar(20) not null unique,
PRIMARY KEY (id)
)
This is my table.
if i insert query like this insert into emp3 values(3,' ','',''); it is getting stored in the table.
but i should avoid this.How can i do it?
You can add constraints according to your needs:
CREATE TABLE emp3(
id int(3) auto_increment,
first_name varchar(30) NOT NULL,
last_name varchar(30),
email varchar(20) not null unique,
PRIMARY KEY (id)
);
ALTER TABLE emp3
ADD CONSTRAINT check_name_not_blank CHECK ((first_name<>'')),
ADD CONSTRAINT check_email_not_blank CHECK ((email<>''))
you yould avoid empty strings in your columns with a constraint like
ALTER TABLE emp3 WITH CHECK
ADD CONSTRAINT [CK_emp3] CHECK
(
([first_name]<>'') AND
([last_name]<>'') AND
([email ]<>'')
)
you can do this just by setting them as Not Null
CREATE TABLE emp3(
id int(3) auto_increment,
first_name varchar(30) NOT NULL,
last_name varchar(30),
email varchar(20) not null unique,
PRIMARY KEY (id)
)
Related
New to SQL, can't figure out what is wrong in my given code. all it says is:
Incorrect syntax near 'DESCRIBE'. [41,1]
I have tried taking off the semi-colons. I really just don't know what it wants from me.
Here is my code. Anything helps, thank you!
-- Write the query to create the 4 tables below.
CREATE TABLE client (
id INT NOT NULL IDENTITY(1,1),
first_name VARCHAR(255) NOT NULL,
last_name VARCHAR(255) NOT NULL,
dob DATE NOT NULL,
PRIMARY KEY (id),
CONSTRAINT (full_name) UNIQUE (first_name, last_name)
);
CREATE TABLE employee (
id INT NOT NULL IDENTITY(1,1),
first_name VARCHAR(255) NOT NULL,
last_name VARCHAR(255) NOT NULL,
dob DATE NOT NULL,
date_joined DATE NOT NULL,
CONSTRAINT (full_name) UNIQUE (first_name, last_name),
PRIMARY KEY (id)
);
CREATE TABLE project (
id INT NOT NULL IDENTITY(1,1),
cid INT NOT NULL,
name VARCHAR(255) NOT NULL,
notes TEXT,
UNIQUE (name),
FOREIGN KEY (cid) REFERENCES client(id)
);
CREATE TABLE works_on (
eid INT NOT NULL,
pid INT NOT NULL,
start_date DATE NOT NULL,
PRIMARY KEY (eid, pid),
FOREIGN KEY (eid) REFERENCES employee(id),
FOREIGN KEY (pid) REFERENCES project(id)
);
-- Leave the queries below untouched. These are to test your submission correctly.
-- Test that the tables were created
DESCRIBE client;
DESCRIBE employee;
DESCRIBE project;
DESCRIBE works_on;
-- Test that the correct foreign keys were created
SELECT TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME,REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE REFERENCED_TABLE_SCHEMA = 'grade';
For MariaDB (and MySQL) the correct syntax for IDENTITY(1,1), is AUTO_INCREMENT, and CONSTRAINT names are not enclosed in (). Any column that is defined as AUTO_INCREMENT must also be declared as a PRIMARY KEY (this is only an issue with the project table). So your CREATE TABLE commands should look like this:
CREATE TABLE client (
id INT NOT NULL AUTO_INCREMENT,
first_name VARCHAR(255) NOT NULL,
last_name VARCHAR(255) NOT NULL,
dob DATE NOT NULL,
PRIMARY KEY (id),
CONSTRAINT full_name UNIQUE (first_name, last_name)
);
CREATE TABLE employee (
id INT NOT NULL AUTO_INCREMENT,
first_name VARCHAR(255) NOT NULL,
last_name VARCHAR(255) NOT NULL,
dob DATE NOT NULL,
date_joined DATE NOT NULL,
CONSTRAINT full_name UNIQUE (first_name, last_name),
PRIMARY KEY (id)
);
CREATE TABLE project (
id INT NOT NULL AUTO_INCREMENT,
cid INT NOT NULL,
name VARCHAR(255) NOT NULL,
notes TEXT,
PRIMARY KEY (id),
UNIQUE (name),
FOREIGN KEY (cid) REFERENCES client(id)
);
CREATE TABLE works_on (
eid INT NOT NULL,
pid INT NOT NULL,
start_date DATE NOT NULL,
PRIMARY KEY (eid, pid),
FOREIGN KEY (eid) REFERENCES employee(id),
FOREIGN KEY (pid) REFERENCES project(id)
);
Demo on dbfiddle
I know the error 150 is related to foreign keys, but i can't figure out what wrong here.
CREATE TABLE IF NOT EXISTS User(
id_user INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
nom VARCHAR(255) NOT NULL,
prenom VARCHAR(255) NOT NULL,
naissance DATE NOT NULL,
email VARCHAR(255) NOT NULL
);
CREATE TABLE IF NOT EXISTS Livre(
id_livre INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
titre VARCHAR(255) NOT NULL,
parution DATE NOT NULL,
id_edit INT NOT NULL,
id_user INT NOT NULL,
FOREIGN KEY ( id_edit)
REFERENCES Editeur(id_edit)
ON DELETE CASCADE,
FOREIGN KEY ( id_user)
REFERENCES User(id_user)
ON DELETE CASCADE
);
CREATE TABLE IF NOT EXISTS Publication(
id_pub INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
texte TEXT NOT NULL,
date_pub DATE NOT NULL,
titre_pub VARCHAR(255) NOT NULL,
id_livre INT NOT NULL,
id_user INT NOT NULL,
FOREIGN KEY ( id_user)
REFERENCES User(id_user)
ON DELETE CASCADE,
FOREIGN KEY (id_livre)
REFERENCES Livre(id_livre)
ON DELETE CASCADE
);
CREATE TABLE IF NOT EXISTS Editeur(
id_edit INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
nom VARCHAR(255) NOT NULL,
pays VARCHAR(255) NOT NULL,
adresse VARCHAR(255) NOT NULL,
tel VARCHAR(255) NOT NULL
);
The error occurs when i try to create tables Livre and Publication.
Types are the same so it doesn't seem to be the problem.
By mindful of the order in which you create the tables.
For instance, your table creation statement for Livre defines a foreign key on Editeur. But the table Editeur has not been created yet.
Adjust the create table statement ordering as required.
For some reason I'm getting an error* in my code. I'm quite new to PostgreSQL, and simply SQL. What is causing this error?
*there is no unique constraint matching given keys for referenced table "tech".
BEGIN;
CREATE TABLE Person (
person_id SERIAL PRIMARY KEY,
firstname VARCHAR(128),
lastname VARCHAR(128),
email_adr VARCHAR(128),
UNIQUE(person_id, email_adr)
);
CREATE TABLE Phone (
person_id INT REFERENCES Person(person_id),
phone_nr INT PRIMARY KEY,
UNIQUE(phone_nr)
);
CREATE TABLE Tech (
tech_id INT REFERENCES Person(person_id),
username VARCHAR(80) PRIMARY KEY,
password VARCHAR(80) NOT NULL,
location Varchar(128),
UNIQUE(username, tech_id)
);
CREATE TABLE Customer (
customer_id INT REFERENCES Persons(person_id),
addresse VARCHAR(255) NOT NULL,
UNIQUE(customer_id)
);
CREATE TABLE Task (
task_id SERIAL PRIMARY KEY,
payment MONEY,
tech INT REFERENCES Tech(tech_id) NOT NULL,
customer INT REFERENCES Customer(customer_id) NOT NULL,
start_date DATE NOT NULL,
end_dato DATE,
UNIQUE(tech, customer, start_date, end_date)
);
COMMIT;
In table Task you trying to reference to table Tech by tech_id. To do that you must add UNIQUE CONSTRAINT to tech_id in Tech.
Right now in table Tech you have UNIQUE(username, tech_id) that means that values in column tech_id could by doubled Ex.
Tech
-------------------------------
tech_id username, ....
------------------------------
1 'John'
2 'Tony'
1 'Nataly'
Acctually the better idea is to set reference by PRIMARY KEY, so in your case username in table Tech.
If you want to leave structure the way present in question, you should just add UNIQUE(tech_id) in column Tech.
What do you think of this code?
BEGIN;
CREATE TABLE Person (
person_id SERIAL PRIMARY KEY,
firstname VARCHAR(128),
lastname VARCHAR(128),
email_adr VARCHAR(128),
UNIQUE(person_id),
UNIQUE(email_adr)
);
CREATE TABLE Phone (
person_id INT,
phone_nr INT PRIMARY KEY,
);
CREATE TABLE Tech (
tech_id INT,
username VARCHAR(80) PRIMARY KEY,
password VARCHAR(80) NOT NULL,
location Varchar(128),
FOREIGN KEY(tech_id) REFERENCES Person(person_id),
UNIQUE(username),
UNIQUE(tech_id)
);
CREATE TABLE Customer (
customer_id INT REFERENCES Persons(person_id),
addresse VARCHAR(255) NOT NULL,
FOREIGN KEY(tech_id) REFERENCES Person(person_id),
UNIQUE(customer_id)
);
CREATE TABLE Task (
task_id SERIAL PRIMARY KEY,
payment MONEY,
tech varchar(80) REFERENCES Tech(username) NOT NULL,
customer INT REFERENCES Customer(customer_id) NOT NULL,
start_date DATE NOT NULL,
end_dato DATE,
UNIQUE(tech, customer, start_date, end_date)
);
COMMIT;
CREATE TABLE detectives(
id INTEGER NOT NULL AUTO_INCREMENT,
first_name VARCHAR(50),
last_name VARCHAR(50) NOT NULL,
phone_number VARCHAR(10) NOT NULL,
certification_date DATE NOT NULL,
CONSTRAINT detectives_pk PRIMARY KEY (id
);
It says: Incorrect syntax near 'AUTO_INCREMENT'.
Any help with this?
Missing closing ) and using incorrect syntax for an IDENTITY field.
CREATE TABLE detectives(
id INT IDENTITY,
first_name VARCHAR(50),
last_name VARCHAR(50) NOT NULL,
phone_number VARCHAR(10) NOT NULL,
certification_date DATE NOT NULL,
CONSTRAINT detectives_pk PRIMARY KEY (id)
)
Change
id INTEGER NOT NULL AUTO_INCREMENT,
To
ID INT NOT NULL IDENTITY(1,1),
you've to make the column identity if you want auto increment. your code will be
CREATE TABLE detectives(
id INT NOT NULL IDENTITY (1, 1),
first_name VARCHAR(50),
last_name VARCHAR(50) NOT NULL,
phone_number VARCHAR(10) NOT NULL,
certification_date DATE NOT NULL,
CONSTRAINT detectives_pk PRIMARY KEY (id)
);
the Staff table references the branch table
CREATE TABLE Staff(
StaffNo VARCHAR(5) NOT NULL,
firstName VARCHAR(15) NOT NULL UNIQUE,
lastName VARCHAR(15) NOT NULL,
position VARCHAR(10) NOT NULL,
salary INTEGER
DEFAULT 3000,
CHECK (salary BETWEEN 3000 AND 25000),
email VARCHAR(25),
branchNo CHAR(6) NOT NULL,
PRIMARY KEY (StaffNo),
FOREIGN KEY (branchNo) REFERENCES Branch (branchNo));
and at the same time the branch table references the Staff table
create table Branch(
branchNo char(6) not null primary key,
street varchar(30) not null,
city varchar(20),
postCode char(5) not null,
ManagerNo varchar(5) not null,
foreign key (ManagerNo) references Staff(StaffNo));
Since your tables reference each other in the Foreign Keys you will get an error on either table creation if the other table has not been created yet. I would suggest that you remove the creation of the FOREIGN KEYs to separate ALTER TABLE statements:
CREATE TABLE Staff(
StaffNo VARCHAR(5) NOT NULL,
firstName VARCHAR(15) NOT NULL UNIQUE,
lastName VARCHAR(15) NOT NULL,
position VARCHAR(10) NOT NULL,
salary INTEGER
DEFAULT 3000,
CHECK (salary BETWEEN 3000 AND 25000),
email VARCHAR(25),
branchNo CHAR(6) NOT NULL,
PRIMARY KEY (StaffNo)
);
create table Branch(
branchNo char(6) not null primary key,
street varchar(30) not null,
city varchar(20),
postCode char(5) not null,
ManagerNo varchar(5) not null
);
alter table staff
add constraint fk1_branchNo foreign key (branchNo) references Branch (branchNo);
alter table branch
add constraint fk1_ManagerNo foreign key (ManagerNo) references Staff (StaffNo);
See SQL Fiddle with Demo
You can remove one reference from one table and keep the other.then you can retrieve data using the remainig reference.Is there any problem with that?