CRUD Operations in PostgreSQL

CRUD stands for:

C: Create (Insert)

R: Read (Select)

U: Update

D: Delete

This section introduces the commands to perform each of these operations on PostgreSQL tables.

Insert operation:

It is used to insert entries into the database relations (tables).

Syntax:

insert into table_name  
(column1,   
column2,   
----
columnN)    
values (value1, value2, value3, ___ valueN);    

For inserting multiple rows together, we specify the values for each row, separated by commas as follows:

Select operation: 

The select operation is used to retrieve specific data from the database.

Syntax:

select 
column1, 
column2,  
----
columnN   
from table_name;    

To select values from all columns, we can use * instead of writing all columns.

 

Update operation:

The update operation lets one update the already existing data in the database.

Syntax:

update table_name    
set 
column1 = value1,   
column2 = value2,
----   
columnN = valueN    
where   
condition;    

The where clause is used to specify the condition that must be satisfied by the rows whose column values need to be updated.

Delete operation:

The delete command is used to delete existing records (rows) that satisfy the given condition (specified using where clause) from the table.

Syntax:

delete from table_name    
where [condition]; 

If no condition is specified, then all the rows of the table get deleted.