[SOLVED] Update question

[jim.davidson]

I have a table with 3 fields

field1 is an int

field2 is an int

field3 is an varchar

 

I need to take the values from  fields 1 and 2, combine them and put the result in field3.

 

Example field1 = 4567

            field2 = 2345

            field3 = "45672345"

 

How would I write the update command?

[gluck]

use CONCAT to combine fields 1 and 2 and insert in 3.

[jim.davidson]

So something like this?

 

update orders set field3 = concat(field1,field2)

[Wildbug]

Look in the MySQL manual, chapter 12 on functions, specifically the LPAD() and CONCAT() functions.

 

UPDATE table_name SET field3=CONCAT(LPAD(field1,4,'0'),LPAD(field2,4,'0'));

 

From your example I've assumed that you have four digit numbers and want an eight character string.  If you want something different, you can probably find functions to fit your needs.

[jim.davidson]

Thank you one last question i only want to do this if field3 is empty so how to I tell if it's empty, is there a function for that?

 

UPDATE table_name SET field3=CONCAT(LPAD(field1,4,'0'),LPAD(field2,4,'0')) where field3 empty;

 

I new to mysql, but tryng

[gluck]

use WHERE field is null or field = '' depending on what you have in the DataBase.

[jim.davidson]

Thanks all, hopfully someday I can give answers instead of asking questions