PostgreSQL Create Table

PostgreSQL uses the CREATE TABLE statement to create database tables.

Syntax

CREATE TABLEThe syntax format is as follows:

CREATE TABLE table_name(
   column1 datatype,
   column2 datatype,
   column3 datatype,
   .....
   columnN datatype,
   PRIMARY KEY( 一个或多个列 )
);

CREATE TABLEis a keyword used to tell the database system that a data table will be created.

The table name must be unique among other tables, sequences, indexes, views, or foreign table names in the same schema.

CREATE TABLECreates a new empty table in the current database; the table will be owned by the user issuing this command.

Each field in the table defines a data type, as follows:

Example

The following creates a table with the table nameCOMPANYtable, with the primary key beingID，NOT NULLindicates that the field does not allowNULLvalue:

CREATE TABLE COMPANY(
   ID INT PRIMARY KEY     NOT NULL,
   NAME           TEXT    NOT NULL,
   AGE            INT     NOT NULL,
   ADDRESS        CHAR(50),
   SALARY         REAL
);

Next, let's create another table that will be used in later chapters:

CREATE TABLE DEPARTMENT(
   ID INT PRIMARY KEY      NOT NULL,
   DEPT           CHAR(50) NOT NULL,
   EMP_ID         INT      NOT NULL
);

We can use the\dcommand to check whether the table was created successfully:

exampledb=# \d
           List of relations
 Schema |    Name    | Type  |  Owner   
--------+------------+-------+----------
 public | company    | table | postgres
 public | department | table | postgres
(2 rows)

\d tablenameView table information:

exampledb=# \d company
                  Table "public.company"
 Column  |     Type      | Collation | Nullable | Default 
---------+---------------+-----------+----------+---------
 id      | integer       |           | not null | 
 name    | text          |           | not null | 
 age     | integer       |           | not null | 
 address | character(50) |           |          | 
 salary  | real          |           |          | 
Indexes:
    "company_pkey" PRIMARY KEY, btree (id)