vb.net中的Ms.Access查询从tbl1中选择全部，从tbl2中仅选择一列

Question

I have 2 tables:

• tbl1(ID, Name, Sex, OrderDate)
• tbl2(OrderDate, OrderCode)

I try to display all data from tbl1 (ID, Name, Sex, OrderDate) and only one column from tbl2(OrderCode) .

I have tried this

SELECT tbl1.*, tbl2.OrderCode FROM tbl1, tbl2;

but it shows duplicate data. like this

I have search a while but only see query of mySQL where they use join but it appears syntax error clause.

I want it appears like this ID Name Sex OrderDate OrderCode OrderCode is autoNumber Random which is why I put it in other table since Access not allow 2 autoNumber in same table

Answer 1

You are doing a CROSS JOIN which results in a cartesian product

You should JOIN on the field that is common in the 2 tables to limit the rows returned.

In your case the only field I see on both tables is OrderDate, and that's a bit weird.

Try this

SELECT tbl1.*, tbl2.OrderCode FROM tbl1, tbl2 WHERE tbl1.OrderDate=tbl2.OrderDate

Answer 2

Create two tables as following:

and then use this query

select t1.ID, t1.Name, t1.Sex, t2.OrderDate, t2.OrderCode from 
Table1 t1
inner join Table2 t2 on t1.ID = t2.ID;

Answer 3

请注意，您的表tbl1（ID，名称，性别，OrderDate）tbl2（OrderDate，OrderCode）没有关系，您必须先关联这两个表，然后才能选择列。.尝试以下操作：新建表：tbl1（ID，名称， Sex，OrderDate）tbl2（ID，OrderDate，OrderCode）tbl1.Id是主键，Tbl2.ID是外键，并且我将选择Tbl1中的所有列和tbl2中的一列（无论大小写限制）

Select tbl1.Id,tbl1.name,tbl1.sex,tbl1.Orderdate,tbl2.orderdate from tbl1,tbl2 where tbl1.id=tbl2.id

Answer 4

When you want to get a result that has a relationship with two tables, that means you want to use Join.

you can also use distinct when you have redundant result.

SELECT DISTINCT tbl1.*, tbl2.OrderCode FROM tbl1, tbl2;