Conditionals

[Michael Smith]

I am trying to write code to deal with a conditional in MySQL.

I have the latest free Invoice Number stored in a table "Storage01" in field "Nextra5". There is only 1 row in the table.

I want to see if the new file being built in the "Invoices01" table already has an Invoice Number. If it doesn't contain any invoice numbers then I would populate the column "invnbr" with @mnewnumber.

I cannot get to first base with this. The most promising version is below but this unfortunately only generates error messages.

SELECT @mnewnumber := Nextra5 from Storage01 ;

SELECT count(ITEM) FROM Invoices01 as V1 where invnbr > 0;

IF V1 = 0 THEN
update Invoices01 set invnbr = @mnewnumber;
ENDIF;


Mike