Access-SQL:具有多个表的内部联接 [英] Access-SQL: Inner Join with multiple tables
问题描述
我在数据库中有多个表:
i have multiple tables in a database:
tblOjt
ID studentid courseid companyid addresseeid dateadded datestarted dateended ojthours
1 3 1 1 1 9/25/2013 500
tblStudent
ID lastname firstname middlename course gender renderedhours dateadded archive
3 Dela Cruz Juan Santos BSIT Male 500
tblCourse
ID coursealias coursename hours
1 BSIT Bachelor of Science in Information Technology 500
tblCompany
ID companyname
1 MyCompany
tblAddressee
ID addresseename
1 John dela Cruz
我需要有一条SQL语句,可以在其中获取以下值:
i need to have a SQL statement in which i can get this values:
tableOjt.id tableOJT.surname,firstname, and middlename course companyname addresseename dateadded datestarted dateended ojthours
我将如何使用那些连接方法在SQL中获取此代码...将其用VB6 ADODC编写,这与标准SQL中的语法相同吗?谢谢
how will i get this code in SQL using those join methods...im writing it in VB6 ADODC, is this the same syntax in a standard SQL ? thanks
推荐答案
如果要针对Access数据库后端编写查询,则需要使用以下联接语法:
If you are writing a query against an Access database backend, you need to use the following join syntax:
select
t1.c1
, t2.c2
, t3.c3
, t4.c4
from ((t1
inner join t2 on t1.something = t2.something)
inner join t3 on t2.something = t3.something)
inner join t4 on t3.something = t4.something
表名和列名在这里并不重要,但括号的位置很重要.基本上,您需要在from
子句后的 n-2 左括号中,在每个新的join
子句的开始之前的右括号中,第一个除外,其中第一个 n 是连接在一起的表的数量.
The table and column names aren't important here, but the placement of the parentheses is. Basically, you need to have n - 2 left parentheses after the from
clause and one right parenthesis before the start of each new join
clause except for the first, where n is the number of tables being joined together.
原因是Access的联接语法一次仅支持联接两个表,因此,如果需要联接两个以上的表,则需要将多余的表括在括号中.
The reason is that Access's join syntax supports joining only two tables at a time, so if you need to join more than two you need to enclose the extra ones in parentheses.
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