Question

I don’t know if this question has been asked previously also. If so please direct me to the link.

I have a table that has three columns name, type and date. Type can only be 4 values A, B, C and D

I want to fetch all those records which are of type A, B or C but the condition is that it should only fetch if the same name also has a type of D.

e.g. lets consider this table

Name      type    Date 
abc        A       5/7
abc        B       6/7
abc        D       7/7

xyz        A       5/7
xyz        D       6/7

lmn        A       5/7
lmn        B       6/7
lmn        C       7/7

So the deal here I need the following result set

ABC 5/7
ABC 6/7
XYZ 5/7

Because ABC and XYZ has a type D the other records of ABC and XYZ are shown. Since lmn does not have a type D it’s not included in the result set.

Answer 1

To test if a record exist, you can simply use where exists :

select * from mytable t1 where exists (
     select * from mytable t2 where t1.Name=t2.Name and t2.type="D"
);

That’s probably self explanatory but here’s a reference : http://dev.mysql.com/doc/refman/5.0/en/exists-and-not-exists-subqueries.html

If you want to exclude the D records, you do this :

select * from mytable t1 where t1.type<>"D" and exists (
     select * from mytable t2 where t1.Name=t2.Name and t2.type="D"
);