UPDATE in PostgreSQL



Using the UPDATE statement, we can change the value of the existing records in the table. Sometimes we need to change the value of the column(s) as per requirements. Suppose we have the "Employee" table and we need to update the salary of a particular employee, it means we will update the salary which already exists in the "Employee" table. But do it carefully because it is very critical to update any records into the table; you must apply where clause in update statement because if you don't use WHERE clause, then it will update all records of your table, which may create a big issue for you. So please be careful before running the UPDATE statement.

PostgreSQL UPDATE syntax



UPDATE table_name
SET col1 = val1,
    col2 = val2 ,...
WHERE
   condition;
  
table_name is the name of the table which records you want to update, and it comes after UPDATE keywords.

col1,col1 are the column name of the table which particular value wants to change. It comes after the SET keyword, and if you update values in multiple columns, you use a comma (,) to separate each pair of column and value.

WHERE clause is very crucial when you are updating any table’s records, so be careful.

PostgreSQL UPDATE examples

Suppose we have the following table. You can create an Employee table using the below PostgreSQL statement.


CREATE TABLE public."Employee"
(
    "Id" bigserial NOT NULL,
    "FName" text COLLATE pg_catalog."default",
    "LName" text COLLATE pg_catalog."default",
    "UserName" text COLLATE pg_catalog."default",
    "Password" text COLLATE pg_catalog."default",
    "Contact" text COLLATE pg_catalog."default",
    "Salary" numeric NOT NULL DEFAULT 0.0,
    CONSTRAINT "PK_Test" PRIMARY KEY ("Id")
)

Insert some records on the above table ("Employee")


INSERT INTO public."Employee"(
  "FName", "LName", "UserName", "Password", "Contact", "Salary")
  VALUES ('Name1','last1', 'name1@gmail.com', 'name@0123', '9088877787', '20000');

INSERT INTO public."Employee"(
  "FName", "LName", "UserName", "Password", "Contact", "Salary")
  VALUES ('Name2','last2', 'name2@gmail.com', 'name@0123', '9288877787', '30000');
              
INSERT INTO public."Employee"(
  "FName", "LName", "UserName", "Password", "Contact", "Salary")
  VALUES ('Name3','last3', 'name3@gmail.com', 'name@0123', '9388877787', '40000');

Illustrates of PostgreSQL UPDATE


Suppose the employee whose name is "Name2" got promotion and salary appraisal (50000), so the HR department needs to update employee salary in "Employee" table, so to update the particular employee's existing records, we will use the following PostgreSQL statement.


UPDATE public."Employee"
  SET "Salary"=50000
  WHERE "UserName"='name2@gmail.com' AND "Password"='name@0123'

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