how to create a table

how to create  a table

CREATE TABLE table_name (

column1 datatype,

column2 datatype,

column3 datatype,

....

);

CREATE TABLE Persons (

PersonID int,

LastName varchar(255),

FirstName varchar(255),

Address varchar(255),

City varchar(255)

);

create table using another table

CREATE TABLE new_table_name AS

SELECT column1, column2,...

FROM existing_table_name

WHERE ....;

CREATE TABLE TestTable AS

SELECT customername, contactname

FROM customers;

how to create a table with constraings datatypes
CREATE TABLE table_name (
column1 datatype constraint,
column2 datatype constraint,
column3 datatype constraint,
....
);
not null
CREATE TABLE Persons (	without data it will not accept
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255) NOT NULL,
Age int
); hwo can we define the total values in column is unique CREATE TABLE Persons (     ID int NOT NULL UNIQUE,     LastName varchar(255) NOT NULL,     FirstName varchar(255),     Age int ); primary key he PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields). CREATE TABLE Persons (     ID int NOT NULL,     LastName varchar(255) NOT NULL,     FirstName varchar(255),     Age int,     PRIMARY KEY (ID) ); sql check The CHECK constraint is used to limit the value range that can be placed in a column. If you define a CHECK constraint on a single column it allows only certain values for this column. If you define a CHECK constraint on a table it can limit the values in certain columns based on values in other columns in the row. CREATE TABLE Persons (     ID int NOT NULL,     LastName varchar(255) NOT NULL,     FirstName varchar(255),     Age int,     CHECK (Age>=18) );

default
using this we can made that value is default, if user is not entered, that default value is show
CREATE TABLE Persons (
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
City varchar(255) DEFAULT 'Sandnes'
);
CREATE TABLE Orders (
ID int NOT NULL,
OrderNumber int NOT NULL,	date
OrderDate date DEFAULT GETDATE()
);

autoincriment
CREATE TABLE Persons (
Personid int NOT NULL AUTO_INCREMENT,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
PRIMARY KEY (Personid)
);