proc sql update statement with inner join

[Ravikumarkummari]

Can any one explain the inner join on condition (ON a.date=b.DATE - 1 YEAR) in below query

proc sql;
alter table k.data_products
add var1 NUM(8)
add var2 NUM(8)
add var3 NUM(8)
add var4 NUM(8)
add var5 NUM(8);

update k.data_products1 a
set a.var1=b.c_var1,a.var2=b.c_var2,a.var3=b.c_var3
FROM k.data_products1 a INNER JOIN k.data_products2 b
ON a.date=b.DATE - 1 YEAR;

[LinusH]

That isn't valid syntax.

Ask the person who created the code.

[Kurt_Bremser]

Since it's a syntax error, there's nothing to explain.