How to Execute Two Query Statements, Query Statements in DOS

resultset is an interface, of course, you can't use new directly.

How do you want to use your result set, do you want to do it separately?

It is still necessary to associate the contents of the result set twice.

If it's the first case, then you can do it for the first time.

After the results then rs = ;

If the two result sets are related, then figure out how to do it on the SQL statement.

Query with views or combinations.

You can use federated queries as follows:

select * from article where id='+id+' and pid='+id+'";

Try the query above.

Yes, type sqlcmd in the runtime, and then you can add go when you want to execute the statement

For example: 1) use student

2)go1)select * from user2)go

The syntax of SQL and HQL is the same, the only difference is that SQL manipulates database fields.

HQL operands.

Change the field name in your SQL statement to the corresponding properties of the entity class.

Either way.

1. Select dyiczk

from khm03

where khhyzl in ( select khhyzl from khm01 where khhykh =

Two: select

from khm03

inner join khm01 on =where =

The execution plan is no different.

The principle, the steps, etc., are all the same, but the result is different.

The question is too abstract.

What is the execution plan.

The second one, select distinct name from tab where pro=1, this is the first selection, then grouping, and then projection.

select name from tab where pro=1 group by name is grouped first and then projected in selection.

For this table, if you press pro=1, you can divide it into five groups, and by name it can be divided into four groups. What we want to get is data with no duplicate results, so grouping by name is a bit more efficient.

Queries in groups are very efficient. You can check out the SQL 2008 book.

Even if you think that only for these two simple SQL statements, the efficiency is the same.

In the absence of other selections, both statements are selected first and then grouped.

That's normal, for example.

c The value in the example is'c1'with C2'

c#='c2'Time s has 1,2,3

c#='c1'Time s also has 1,2,3

Article 1 requires s not in (1,2,3) and Article 2 requires s in (1,2,3).

Yes, the result is the same under normal circumstances! I don't know if column c in table sc has a null value, please note!

It is different, the judgment conditions of the SC table are different, the results must be different, and the results you expect will definitely be different.

select s# from sc where c# = 'c2'If there is null, then the value cannot be found in not in, and if there is no null, it is still the same.

dim ch

ch=" select * from kcinfo "

ch,dbcon,1,1 'Query-only does not update, deletes writes, 3,3 updatable, writes, deletes, I can't remember clearly because I haven't written asp for too many years. The error of this is usually that the database is not opened.

There is a problem with the variable of dbcon, the database is not opened, so the variable is dbcon=null so it is wrong, or the query parameter of rs is not opened, so it is wrong, check whether the database has been opened by yourself.