Execute different WHERE statement based on IF conditions depending on @variable?

I have a nativeQuery in my DAO layer inside my Spring Boot app.

Basically, I’ passing three parameters, like so:

@Query(name = "findInvoicesTour", nativeQuery = true)
    List<InvoiceDto> findInvoices(@Param("invoiceNumber") String invoiceNumber, @Param("companyName") String companyName, @Param("paid") boolean paid);

I would like to have different WHERE statements executing depending on value of companyName, something like this:

if(:companyName = '')
    SELECT col1, col2, col3
    FROM invoice_tour it
    WHERE it.paid =: paid AND it.invoice_number LIKE :invoiceNumber
ELSE
    SELECT col1, col2, col3
    FROM invoice_tour it
    WHERE it.paid =: paid AND it.invoice_number LIKE :invoiceNumber AND it.companyName := companyName

Or

SELECT col1, col2, col3
 if(:companyName = '')
        FROM invoice_tour it
        WHERE it.paid =: paid AND it.invoice_number LIKE :invoiceNumber
 ELSE
        FROM invoice_tour it
        WHERE it.paid =: paid AND it.invoice_number LIKE :invoiceNumber AND it.companyName := companyName

Answer

Use boolean logic:

SELECT col1, col2, col3
FROM invoice_tour it
WHERE 
    it.paid =: paid 
    AND it.invoice_number LIKE :invoiceNumber
    AND (:companyName = '' OR it.companyName := companyName)