In this article, we are going to see how to use the limit clause in PostgreSQL using pyscopg2 module in Python. In PostgreSQL LIMIT constraints the number of rows returned by the query. By default, It is used to display some specific number of rows from the top. If we want to skip a number of rows before returning the rows then we use the OFFSET clause after the LIMIT clause.
Syntax without using OFFSET: SELECT select_list FROM table_name LIMIT no_of_rows;
Syntax with using OFFSET: SELECT select_list FROM table_name LIMIT no_of_rows OFFSET rows_to_skip;
Table Used:
Here, we are using the product table for demonstration.
Now let’s use the limit in this table, for we will use will psycopg2 module to connect the PostgreSQL and execute the SQL query in the cursor.execute(query) object.
Syntax: cursor.execute(sql_query);
Example 1: Using a limit clause in Postgre using Python
Python3
# importing psycopg2import psycopg2conn=psycopg2.connect( database="neveropen", user="postgre", password="root", host="localhost", port="5432")# Creating a cursor object using the cursor() methodcursor = conn.cursor()print("\ndisplaying five rows from top");sql = '''SELECT * from products LIMIT 5 '''# Executing the querycursor.execute(sql)# Fetching the dataresult = cursor.fetchall();print(result)# Commit changes in the databaseconn.commit()# Closing the connectionconn.close() |
Output:
Postgre limit clause
Example 2: Using limit and offset clause in Postgre using Python
Python3
# importing psycopg2import psycopg2conn=psycopg2.connect( database="neveropen", user="postgre", password="root", host="localhost", port="5432")# Creating a cursor object using the cursor() methodcursor = conn.cursor()print("displaying four rows after a particular offset");sql1 = '''SELECT * from products LIMIT 4 OFFSET 5 '''# Executing the querycursor.execute(sql1)# Fetching the dataresult1 = cursor.fetchall();print(result1)# Commit changes in the databaseconn.commit()# Closing the connectionconn.close() |
Output:
Postgre limit clause with offset
