Python PostgreSQL - Limit

While executing a PostgreSQL SELECT statement you can pmit the number of records in its result using the LIMIT clause.

Syntax

Following is the syntax of the LMIT clause in PostgreSQL −

SELECT column1, column2, columnN
FROM table_name
LIMIT [no of rows]

Example

Assume we have created a table with name CRICKETERS using the following query −

postgres=# CREATE TABLE CRICKETERS ( 
   First_Name VARCHAR(255), Last_Name VARCHAR(255), Age int, 
   Place_Of_Birth VARCHAR(255), Country VARCHAR(255)
);
CREATE TABLE
postgres=#

And if we have inserted 5 records in to it using INSERT statements as −

postgres=# insert into CRICKETERS values ( Shikhar ,  Dhawan , 33,  Delhi ,  India );
INSERT 0 1
postgres=# insert into CRICKETERS values ( Jonathan ,  Trott , 38,  CapeTown ,  SouthAfrica );
INSERT 0 1
postgres=# insert into CRICKETERS values ( Kumara ,  Sangakkara , 41,  Matale ,  Srilanka );
INSERT 0 1
postgres=# insert into CRICKETERS values ( Virat ,  Kohp , 30,  Delhi ,  India );
INSERT 0 1
postgres=# insert into CRICKETERS values ( Rohit ,  Sharma , 32,  Nagpur ,  India );
INSERT 0 1

Following statement retrieves the first 3 records of the Cricketers table using the LIMIT clause −

postgres=# SELECT * FROM CRICKETERS LIMIT 3;
first_name  | last_name  | age | place_of_birth | country
------------+------------+-----+----------------+-------------
Shikhar     | Dhawan     | 33  | Delhi          | India
Jonathan    | Trott      | 38  | CapeTown       | SouthAfrica
Kumara      | Sangakkara | 41  | Matale         | Srilanka
(3 rows)

If you want to get records starting from a particular record (offset) you can do so, using the OFFSET clause along with LIMIT.

postgres=# SELECT * FROM CRICKETERS LIMIT 3 OFFSET 2;
first_name  | last_name  | age | place_of_birth | country
------------+------------+-----+----------------+----------
Kumara      | Sangakkara | 41  | Matale         | Srilanka
Virat       | Kohp      | 30  | Delhi          | India
Rohit       | Sharma     | 32  | Nagpur         | India
(3 rows)
postgres=#

Limit clause using python

Following python example retrieves the contents of a table named EMPLOYEE, pmiting the number of records in the result to 2 −

Example

import psycopg2

#estabpshing the connection
conn = psycopg2.connect(
   database="mydb", user= postgres , password= password , host= 127.0.0.1 , port=  5432 
)

#Setting auto commit false
conn.autocommit = True

#Creating a cursor object using the cursor() method
cursor = conn.cursor()

#Retrieving single row
sql =    SELECT * from EMPLOYEE LIMIT 2 OFFSET 2   

#Executing the query
cursor.execute(sql)

#Fetching the data
result = cursor.fetchall();
print(result)

#Commit your changes in the database
conn.commit()

#Closing the connection
conn.close()

Output

[( Sharukh ,  Sheik , 25,  M , 8300.0), ( Sarmista ,  Sharma , 26,  F , 10000.0)]