I wanna create a table in SQL, and if the I wanna set the attributes to NULL, how do I do it?
For example, I wanna create a table named Courses and its attributes "CourseNo" and "Title" must not be null. I created one below:
CREATE TABLE Courses(
CourseNo INTEGER CHECK(100<=CourseNo<=999) PRIMARY KEY,
Title VARCHAR(100),
)
ALTER TABLE Courses
ALTER COLUMN CourseNo INTEGER NOT NULL
ALTER COLUMN Title VARCHAR(100) NOT NULL
Is this correct?
whatever you wrote that one correct but good practice is to write not null at a time of defining table. do like this:
CREATE TABLE Courses(
CourseNo INTEGER CHECK(100<=CourseNo<=999) PRIMARY KEY,
Title VARCHAR(100) NOT NULL,
)
primary key is by default NOT NULL always, hence you no need to declare it as NOT NULL
NOT NULL in alter is used when u want to make change in column definations of table later
Change that Title VARCHAR(100) to Title VARCHAR(100) NOT NULL.
Related
I am new to PostgreSQL and how i can update the records while they are related with a foreign key definition.
I am getting an error and that would be great if you can guide me with any hints
Let's say we have two different tables like below :
CREATE TABLE IF NOT EXISTS student
(
id_num VARCHAR(40) NOT NULL REFERENCES registered(student_id),
first_name VARCHAR(32) NOT NULL,
last_name VARCHAR(32) NOT NULL,
birthdate DATE NOT NULL,
PRIMARY KEY(id_num)
);
CREATE TABLE IF NOT EXISTS registered
(
student_id VARCHAR(40) NOT NULL UNIQUE,
paid_tuition BOOL NOT NULL,
PRIMARY KEY(paid_tuition)
);
Based on my understating i need to fill the registered table and then try to insert values to the student table that their id match the student_id value in registered table.
But when I try it I get the following error?
Any idea or recommendation?
Message:"update or delete on table "registered" violates foreign key
constraint "student_id_num_id_fkey" on table "student"",
Detail:"Key (id_num)=(idNum-1) is still referenced from table
"student".", Hint:"", Position:0, InternalPosition:0,
InternalQuery:"", Where:"", SchemaName:"", TableName:"student",
ColumnName:"", DataTypeName:"",
ConstraintName:"student_id_num_id_fkey", File:"ri_triggers.c",
Line:2490, Routine:"ri_ReportViolation"}
seems like you are linking tables in opposite direction , to me it makes more sense that "registered" table has been linked to student table by fk studentid .
also in your "student" table definition you are saying that column "id" is primary key while no "id" column has been declared.
so here is what I mean:
CREATE TABLE IF NOT EXISTS student
(
id_num VARCHAR(40) NOT NULL REFERENCES registered(student_id),
first_name VARCHAR(32) NOT NULL,
last_name VARCHAR(32) NOT NULL,
birthdate DATE NOT NULL,
PRIMARY KEY(id_num)
);
CREATE TABLE IF NOT EXISTS registered
(
student_id VARCHAR(40) NOT NULL REFERENCES student(id_num)
paid_tuition BOOL NOT NULL,
PRIMARY KEY(id_num)
);
I am trying to make a simple database with an number generator but why do I get the error below?
ERROR: syntax error at or near "AUTO_INCREMENT"
LINE 2: IDNumber int NOT NULL AUTO_INCREMENT,
Code:
CREATE TABLE Finance
(
IDNumber int NOT NULL AUTO_INCREMENT,
FinName varchar(50) NOT NULL,
PRIMARY KEY(IDNumber)
);
The subject of the question mentions pgAdmin 4, so here's how to do it there.
First, add a column to your table, then click the little edit icon:
Then go to Constraints and select the Identity type:
This generates SQL similar to this:
CREATE TABLE public.my_table_name
(
id integer NOT NULL GENERATED ALWAYS AS IDENTITY,
PRIMARY KEY (id)
);
For Postgres you have to use SERIAL
CREATE TABLE Finance
(
IDNumber SERIAL PRIMARY KEY,
FinName varchar(50) NOT NULL
);
IN pgadmin-2.
step 01:
create seq:
and set info:
step 02: go to ID in table and set constraints
if it is sql the syntax is the following
CREATE TABLE Persons (
ID int IDENTITY(1,1) PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int
);
You are using a MySQL syntax which won't work in SQL Server.
CREATE TABLE Finance
(
IDNumber int NOT NULL IDENTITY(1,1) PRIMARY KEY,
FinName varchar(50) NOT NULL
);
The following code should work for SQL Server.
IDENTITY(1,1) is SQL Server's way of saying "auto increment".
The starting value for IDENTITY is 1, and it will increment by 1 for each new record.
So : IDENTITY(startvalue, incrementvalue)
there are two options; one is to use the "datatype" serial or create a sequence and use this sequence as a default value for your integer as follows:
CREATE SEQUENCE your_seq;
CREATE TABLE foo(
id int default nextval('your_seq'::regclass),
other_column TEXT);
INSERT INTO foo(other_column) VALUES ('bar') RETURNING *;
It is important to note that specifying a table as follows:
CREATE TABLE tablename (
colname SERIAL);
is equivalent to:
CREATE SEQUENCE tablename_colname_seq AS integer;
CREATE TABLE tablename (
colname integer NOT NULL DEFAULT nextval('tablename_colname_seq'));
ALTER SEQUENCE tablename_colname_seq OWNED BY tablename.colname;
More information about serial can be found here.
I wanna create the following table:
create table product (id bigint not null, product_type varchar(50), product_name varchar(100), available_from TIMESTAMP, available_to TIMESTAMP, primary key (id));
My table's key is the 'id'.
when inserting in the table, I wanna that the product_type be unique.
How to do that without setting the product_type the key for my table
ALTER TABLE <your table name>
ADD CONSTRAINT unique_product_type UNIQUE(product_type);
I can't see a table name in your create table SQL.
The function NEWID() generates a new unique id. Maybe you can make a trigger which insets this in every insert or make the default value to be NEWID(). Well the second option seems a bit better :P
CREATE TABLE Test123
(
ID NVARCHAR(200) DEFAULT (NEWID()),
name NVARCHAR(100)
)
INSERT INTO Test123 (name) VALUES ('test')
SELECT * FROM Test123
DROP TABLE Test123
Add a unique constraint, something like this (not tested):
http://www.w3schools.com/sql/sql_unique.asp
CREATE TABLE Product
(
id bigint NOT NULL,
product_type varchar(50),
product_name varchar(100),
available_from TIMESTAMP,
available_to TIMESTAMP,
primary key (id),
UNIQUE (product_type)
)
CREATE TABLE DEPARTMENT(
DEPARTMENT_NAME VARCHAR(25) NOT NULL PRIMARY KEY ,
BUDGET_CODE INT NOT NULL,
OFFICE_NUM INT NOT NULL,
PHONE NUMERIC NOT NULL ,
);
I have this table that I am creating but i want to change budget code and office number in varchar instead of int. Is there a way to do this. this table is linked to other tables with foreign key. So i can't drop it and create a new one.
Try this
ALTER TABLE dbo.DEPARTMENT
ALTER COLUMN BUDGET_CODE VARCHAR(100)
ALTER COLUMN OFFICE_NUM VARCHAR(100)
CREATE DATABASE agom COLLATE Arabic_CI_AS
CREATE TABLE Branches
(
ID INT PRIMARY KEY NOT NULL IDENTITY,
NAME VARCHAR(255) NOT NULL
)
CREATE TABLE agom.Brands
(
ID INT PRIMARY KEY NOT NULL IDENTITY,
NAME VARCHAR(255) NOT NULL
)
CREATE TABLE agom.Work_Order
(
NUMBER INT NOT NULL,
BRANCHID INT NOT NULL,
BRANDID INT NOT NULL,
WDATE DATE NOT NULL,
REPAIRSTATUS VARCHAR(255),
REPAIRCOST VARCHAR(255),
REMARK VARCHAR(500),
PRIMARY KEY (NUMBER,BRANCHID,BRANDID)
)
CREATE TABLE agom.Profiles
(
ID INT PRIMARY KEY NOT NULL IDENTITY,
USERNAME VARCHAR(25) NOT NULL,
PASS VARCHAR(25) NOT NULL
)
ALTER TABLE agom.Work_Order
ADD CONSTRAINT branchfk
FOREIGN KEY (BRANCHID) REFERENCES Branches(ID)
ALTER TABLE agom.Work_Order
ADD CONSTRAINT brandfk
FOREIGN KEY (BRANDID) REFERENCES Brands(ID)
I get an error that cannot create table
I try to write database name with the table name db.tablename but it's not working
I need to create the database then create the tables and its constraints but I don't know where is the error.I am a sql noob
It's never Database.Table.
It's either Table, or Schema.Table, or Database.Schema.Table, or Server.Database.Schema.Table.
You probably just want to insert USE agom right after create database, and then only refer to tables by name.
Alternatively, you can refer to your tables as agom.dbo.Work_Order, dbo being the default database schema.
See Using Identifiers As Object Names for general reference.