Question

I want to update several columns of a table at the same time. And the value for each column is retrieved from several tables. My tables are:

Table : Customer
Columns are:
customerCode
kategori
design
designCode
value

Table Name : Customer_kategori 
Columns:

customerCode
kategori

and similar …..

My sql query is:

UPDATE Customer
SET 
    kategori = Customer_kategori.kategori,
    design = Customer_design.design,
    designCode = Customer_designCode.designCode,
    value = Customer_value.value

FROM 
     Customer_kategori,
     Customer_design,
     Customer_designCode,
     Customer_value
WHERE
     Customer_kategori.customerCode = Customer.customerCode
     AND Customer_design.customerCode = Customer.customerCode
     AND Customer_designCode.customerCode = Customer.customerCode
     AND Customer_value.customerCode = Customer.customerCode

The columns are updated if all the tables (Customer_kategori, Customer_design, Customer_designCode, Customer_value) contains values. But if tables are empty,
columns are not updated as Where condition is not satisfied.

I also try using CASE in WHERE Condition. My code is ,

WHERE
        Customer_kategori.customerCode = CASE WHEN Customer_kategori.customerCoder IS NOT NULL THEN Customer.customerCode END
        AND Customer_design.customerCode = CASE WHEN Customer_design.customerCode  IS NOT NULL THEN  Customer.customerCode  END
        AND Customer_designCode.customerCode = CASE WHEN Customer_designCode.customerCode  IS NOT NULL THEN  Customer.customerCode  END
        AND  AND Customer_value.customerCode =   CASE WHEN Customer_value.customerCode  IS NOT NULL THEN  Customer.customerCode  END

But this does not work either. I also try to check the table,
with following where clause,

WHERE
    CASE WHEN (select count(Customer_kategori.customerCode) > 0 from Customer_kategori) THEN Customer_kategori.customerCode = Customer.customerCode END

But no success..

In short:

1. I want to check if tables are empty in WHERE clause
2. And if it is empty I just want to ignore checking columns of those table that are empty.

Or may be there is other better way ….
Any suggestion is appreciated…

Thank you

Answer 1

Will this work?

WHERE
(
    Customer_kategori.customerCode = Customer.customerCode
    OR 
    0 = (select count(Customer_kategori.customerCode) from Customer_kategori)
)
AND
(
    ....
)

UPDATE

How about this:

UPDATE Customer
SET 
    kategori = Customer_kategori.kategori,
    design = Customer_design.design,
    designCode = Customer_designCode.designCode,
    value = Customer_value.value

FROM 
     Customer left join Customer_kategori on Customer_kategori.customerCode = Customer.customerCode 
     left join Customer_design on Customer_design.customerCode = Customer.customerCode 
     left join Customer_designCode on Customer_designCode.customerCode = Customer.customerCode 
     left join Customer_value on Customer_value.customerCode = Customer.customerCode