How To Resolve/Fix PostgreSQL Default Value Not Working || PostgreSQL Co...

If you’re facing issues with PostgreSQL default values not working in your columns, this tutorial is here to help. Default values are a key feature in database management, ensuring that specific columns automatically populate with preset data when no value is provided. However, there are times when these default values might not function as expected, leading to potential data inconsistencies or application errors.

In this video, we explore the possible reasons why default values might not be applied in your PostgreSQL database, such as incorrect column definitions, conflicts with triggers, or issues within the pgAdmin interface. We provide a detailed, step-by-step guide to diagnosing and fixing these problems, ensuring that your default values are correctly implemented and operational.

We start by reviewing how to properly set default values in PostgreSQL, including using the SQL DEFAULT clause in table definitions. Then, we demonstrate common pitfalls that could prevent these defaults from working, along with practical solutions to resolve each issue. You'll also learn how to test and validate that the default values are working as intended after applying the fix.

Whether you’re a seasoned database administrator or a developer just getting started with PostgreSQL, this tutorial will equip you with the knowledge to troubleshoot and fix default value issues efficiently. By the end of the video, you'll have a clear understanding of how to manage default values in PostgreSQL, ensuring your database remains reliable and consistent.

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-- In this video, we will

-- Use A Default Value

-- Default Value Not Working

-- Alter Column With A Default Value

-- Alter Column Datatype

-- So, keep watching and subscribe my channel

CREATE TABLE EMP(

ID NUMERIC,

NAME CHARACTER VARYING(20),

SALARY NUMERIC(10,2),

DEPTNO CHARACTER VARYING(10)

);

INSERT INTO EMP(id,name,salary,deptno)

values(1,'Akram',100.23,'10');

select * from emp;

-- Now, let's alter the table, and make Salary column default

Alter table emp alter column salary set default 50;

-- First I will show you when it works and then it won't work.

INSERT INTO EMP(id,name,deptno)

values(2,'Sohail','10');

-- This must have inserted salary as 50, which I have set default value.

-- Let's check

Select * from emp;

-- Now, I will show you when default value won't work

INSERT INTO EMP(id,name,salary,deptno)

values(3,'Knowledge 360',null,'15');

-- Here, the salary must be inserted as NULL

Select * from emp;

-- So, the conclusion is, whenever we give the default value, we do not

-- need to mention the column in the insert statement.

-- If we do so, then we have to put some value, even if it is null

-- The database will accept the null

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How To Create Sequence In PostgreSQL And Usage Of Sequence || Table Prim...

Sequences in PostgreSQL are a powerful tool for managing auto-incrementing values, often used for primary keys in tables or as a part of stored procedures to maintain data consistency and integrity. In this comprehensive tutorial, we walk you through the process of creating and using sequences in PostgreSQL, ensuring you have the skills to implement them effectively in your database projects.

The video starts with an introduction to sequences, explaining what they are and why they are essential in PostgreSQL. We then provide step-by-step instructions on how to create a sequence, from the basic SQL commands to more advanced options that allow you to customize how your sequence behaves.

Next, we explore the practical applications of sequences, particularly how they can be linked to table columns as primary keys, ensuring that each new entry automatically receives a unique value. This is a crucial aspect of database management, as it helps maintain data integrity and avoid conflicts in primary key values.

We also dive into how sequences can be utilized within stored procedures, allowing for dynamic data operations that can adapt to changing conditions within your database. Whether you’re automating tasks or managing large datasets, understanding how to integrate sequences into your stored procedures will make your database operations more efficient and robust.

This tutorial is essential for anyone looking to deepen their PostgreSQL knowledge, particularly in areas related to database management and stored procedures. By the end of the video, you'll be equipped with the skills to create, manage, and utilize sequences effectively in your PostgreSQL databases.

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How To Create Sequence In PostgreSQL And Usage Of Sequence || Table Primary Key || Stored Procedure

CREATE SEQUENCE tbl_emp_seq

START WITH 1 -- VALUE WILL START WITH 1

INCREMENT BY 1 -- IT WILL GET INCREMENT BY 1

MINVALUE 1 -- MINIMUM VALUE CAN BE 1

MAXVALUE 10 -- MAXIMUM VALUE CAN BE 10

CYCLE; -- CYCLE MEANS, AFTER REACHING MAXVALUE, WHICH IS 10 HERE, THE SEQUENCE WILL START AGAIN FROM 1

-- NOW LET'S SEE THE SEQUENCE VALUE

-- USE THE BELOW STATEMENT FOR SEQUENCE VALUE

SELECT NEXTVAL('tbl_emp_seq');

-- THE VALUE REACHED MAXVALUE, NOW IT WILL AGAIN START FROM 1

-- NOW LET'S SEE THE CASE OF NO CYCLE

-- IN CASE OF NO CYCLE, THE SEQUENCE WON'T START AGAIN FROM 1

-- IT WILL THROW AN ERROR AFTER REACHING THE MAX VALUE

DROP SEQUENCE tbl_emp_seq;

CREATE SEQUENCE tbl_emp_seq

START WITH 1 -- VALUE WILL START WITH 1

INCREMENT BY 1 -- IT WILL GET INCREMENT BY 1

MINVALUE 1 -- MINIMUM VALUE CAN BE 1

MAXVALUE 10 -- MAXIMUM VALUE CAN BE 10

NO CYCLE; 

SELECT NEXTVAL('tbl_emp_seq');

-- HERE THE MAX VALUE IS REACHED, SO IF WE TRY TO GET THE VALUE AFTER THAT, WE WILL GET AN ERROR

ERROR:  nextval: reached maximum value of sequence "tbl_emp_seq" (10)

SQL state: 2200H

-- THIS IS WHY WE USUALLY KEEP THE MAXVALUE VERY HIGH AS MUCH POSSIBLE

-- NOW LET'S CREATE AN ACTUAL SEQUENCE AND USE IN A TABLE TO GENERATE VALUES AUTOMATICALLY

CREATE SEQUENCE tbl_emp_seq

START WITH 1 -- VALUE WILL START WITH 1

INCREMENT BY 1 -- IT WILL GET INCREMENT BY 1

MINVALUE 1 -- MINIMUM VALUE CAN BE 1

MAXVALUE 10000000000 -- MAXIMUM VALUE CAN BE 10

NO CYCLE; 

CREATE TABLE EMP

(

EMP_ID INTEGER DEFAULT NEXTVAL('tbl_emp_seq'),

EMP_NAME VARCHAR(50),

SALARY NUMERIC(5,2)

);

INSERT INTO EMP(EMP_NAME,SALARY) VALUES ('AKRAM',100.56);

INSERT INTO EMP(EMP_NAME,SALARY) VALUES ('SOHAIL',670.56);

INSERT INTO EMP(EMP_NAME,SALARY) VALUES ('KNOWLEDGE 360',757.87);

SELECT * FROM EMP;

-- WE CAN SEE, THE EMP_ID VALUES ARE GENERATED FROM SEQUENCE

-- NOW LET'S USE THE SEQUENCE IN A STORED PROCEDURE

CREATE OR REPLACE PROCEDURE public.EMP_PROC()

LANGUAGE 'plpgsql'

AS $BODY$

DECLARE

V_EMP_SEQ_VAL INTEGER;

BEGIN

SELECT NEXTVAL('tbl_emp_seq') into V_EMP_SEQ_VAL;

insert into emp(emp_id,emp_name,salary) values (V_EMP_SEQ_VAL,'New Emp',455.24);

END;

$BODY$;

call public.EMP_PROC();

select * from emp;

SELECT NEXTVAL('tbl_emp_seq');

SELECT CURRVAL('tbl_emp_seq');

-- also we can see the current value of a sequence

-- If you have any doubt, please ask me in the comments.

-- Subscribe the channel to get the videos updates.