SQL if not null update

Question

I have this query

UPDATE users SET username = Param1,email = Param2,PASSWORD = Param3 WHERE id = Param4;

this is updating my user row, but

Answer 1

Maybe this will work:

UPDATE users 
   SET username = Param1, email = Param2, PASSWORD = Param3 
 WHERE id = Param4
   AND CONCAT(email,password) IS NOT NULL;

I've tried with MySQL version 4, 5.x and 8 with MariaDB 10, whenever you do CONCAT on columns where one of the column value is NULL, you'll always get NULL result.

Edit: For empty string, something like this.

UPDATE users 
   SET username = Param1, email = Param2, PASSWORD = Param3 
 WHERE id = Param4
   AND CONCAT(email,password) <> '';

For both NULL and empty string, something like this.

UPDATE users 
   SET username = Param1, email = Param2, PASSWORD = Param3 
 WHERE id = Param4
   AND CONCAT(email,password) IS NOT NULL OR CONCAT(email,password) <> '';

Answer 2

Please check if this works..

 DECLARE @email varchar(100), @password varchar(50)
    SET @email = null  
    SET @password = null

    IF @email <= (SELECT email from users WHERE id = Param4)   
    UPDATE users SET username = Param1,email = Param2,PASSWORD = Param3 WHERE id = Param4;

    IF @password <= (SELECT PASSWORD from users WHERE id = Param4)   
    UPDATE users SET username = Param1,email = Param2,PASSWORD = Param3 WHERE id = Param4;

Answer 3

Like this

UPDATE users 
SET 
  username = Param1,
  email = COALESCE(Param2, email),
  password = COALESCE(Param3, password)
WHERE id = Param4;

COALESCE works from left to right taking the first non null argument. If you provide null as Param2, it will update email to email (no change). If you provide a value to Param2, coalesce will return that non null value so email is updated to whatever param2 is

Ps: understood your request to be "I will provide either a null or a value in the parameter. If I provide a null I don't want to update the db table. If I provide a value I do want to update the DB table"

This seemed more logical to me than how your question reads which is "if my table value is null for email then I forever want it to remain null and never want any of the values I supply in the parameters to be written to the table"

Answer 4

UPDATE users 
SET username = Param1,
email = Param2,
PASSWORD = Param3 
WHERE id = Param4 AND (ISNULL(email,'') != '' OR ISNULL(PASSWORD, '') != '');

Answer 5

If email OR password is not null update them otherwise let them be as they are.

You can use case expressions for this. I think that the logic you want is:

UPDATE users 
SET 
    username = Param1
    email = case when email is not null then Param2 end,
    password = case when password is not null then Param3 end
WHERE id = Param4;

Or if you want to update email and password if both are not null then:

UPDATE users 
SET 
    username = Param1
    email = case when email is not null and password is not null then Param2 end,
    password = case when email is not null and password is not null then Param3 end
WHERE id = Param4;

---

Now the question was updated and I understand that you want to perform the update if and only if both email and password parameters are not empty strings. So you actually want filtering. I would phrase this as:

UPDATE users 
SET username = Param1, email = Param2, password = Param3 
WHERE id = Param4 and Param2 <> '' and Param3 <> ''

Or if you want to separate the logic for both parameters:

UPDATE users 
SET 
    username = Param1, 
    email = case when Param2 <> '' then Param2 else email end, 
    password = case when Param3 <> '' then Param3 else password end
WHERE id = Param4;