MySQL Update Condtional for Three columns Between Two DBs-CodePudding

Having difficulty writing a statement that will allow me to: UPDATE column C in DB1.table1 with data from column B in DB2.table2 IF column B IS NOT null AND column A FROM DB1.table1 = column A FROM DB2.table2 (matching IDs)

Can't tell if I need to use a CASE statement or IF. Appreciate any help, thanks.

CodePudding user response：

UPDATE DB1.table1                                 
  JOIN DB2.table2 ON DB2.table2.B IS NOT NULL     -- IF column B IS NOT null
                 AND DB1.table1.A = DB2.table2.A  -- AND column A FROM DB1.table1 
                                                  -- = column A FROM DB2.table2 (matching IDs)
SET DB1.table1.C = DB2.table2.B                   -- UPDATE column C in DB1.table1 
                                                  -- with data from column B in DB2.table2