W3Schools & SQL Subqueries?

[davej]

Am I mistaken or does the W3Schools tutorial omit all discussion of SQL subqueries?http://www.w3schools.com/sql/default.aspDoes anyone perhaps have a link to a particularly good page offering coverage of this topic?

[Fmdpa]

I remember viewing information on it somewhere - I thought it was the schools, but maybe it was the MySQL ref manual.

[DeathRay2K]

This is where I first learned SQL, and it includes subqueries. It's not perfect, but it's good for a beginner.

[davej]

This is where I first learned SQL, and it includes subqueries. It's not perfect, but it's good for a beginner.

I don't see much there about subqueries. There is some info here;http://msdn.microsoft.com/en-us/library/ms175838.aspxI also wonder if a subquery is always or generally more efficient that the equivalent join?Example;SELECT O.ORDER_ID, O.ORDER_DATEFROM ORDERS OWHERE ORDER_ID IN (SELECT ORDER_ID FROM SALES WHERE CUST_ID IN (SELECT CUST_ID FROM CUSTOMER WHERE Phone = '1231234567' ));...or a 3-way inner join...SELECT DISTINCT O.ORDER_ID, O.ORDER_DATEFROM ORDERS O, SALES S, CUSTOMER CWHERE O.ORDER_ID = S.ORDER_ID AND O.CUSTOMER_ID = C.CUSTOMER_ID AND C.Phone = '1231234567'; Both produce the same results, but is one better, faster, or more efficient?

[davej]

I remember viewing information on it somewhere - I thought it was the schools, but maybe it was the MySQL ref manual.

This actually looks pretty good! Thanks!