SQL/MX 2.x Reference Manual (H06.04+)

SQL/MX Language Elements

HP NonStop SQL/MX Reference Manual—540440-003

6-103

Considerations for Search Condition

Order of Evaluation

SQL evaluates search conditions in this order:

1. Predicates within parentheses

2. NOT

3. AND

4. OR

Column References

Within a search condition, a reference to a column refers to the value of that column in

the row currently being evaluated by the search condition.

Subqueries

If a search condition includes a subquery and the subquery returns no values, the

predicate evaluates to null. See Subquery on page 6-105.

Examples of Search Condition

•

Select rows by using a search condition composed of three comparison predicates

joined by AND operators:

select O.ordernum, O.deliv_date, OD.qty_ordered

FROM sales.orders O,

sales.odetail OD

WHERE qty_ordered < 9 AND deliv_date <= DATE '1998-11-01'

AND O.ordernum = OD.ordernum;

ORDERNUM DELIV_DATE QTY_ORDERED

---------- ---------- -----------

100210 1997-04-10 3

100210 1997-04-10 6

100250 1997-06-15 4

101220 1997-12-15 3

...

--- 28 row(s) selected.