如何在两个mySQL表之间创建“链接”？

Question

I have two tables that look as Follows:

Person (Table Name)

Name1/Phone1/Email1/Address1/Organization1/Notes1 (Fields)

Organization (Table Name)

Organization1/Phone2/Email2/Address2/Web2/Notes2 (Fields)

Organization1 is the only field in common between the two tables.

When I display data on a person, I want to also check and see if there is data on their organization and display it as well if it exists. I'm using PHP to interface with mySQL.

Answer 1

You need to JOIN the tables.

SELECT * FROM Person LEFT JOIN Organization ON Person.Organization = Organization.Name;

This assumes the relationship is the Organization Name. I've done a LEFT JOIN since you said if exists . Check out this tutorial for more detail on joining tables.

Note: I agree and would recommend making your database more relational by adding Primary Keys and using them as Foreign Keys in your other tables.

Answer 2

您应该使用外键 ，但是您需要使用InnoDB存储引擎 （MyISAM尚不支持外键）。

Answer 3

This post is an explanation of relations, not code for you to use. If you want that, look elsewhere
Well, connections between tables are called relations. There are 3 types of relations.

1) One -> One - This type of relation means 1 row is related to 1 other row in a different table

2) One -> Many - This type of relation means 1 row is related to a variable number of rows in a different table.
An example may be A folder can have multiple files, but a file can't have multiple folders. So in this case the 1 would be the folder, and the many would be the files.

3) Many -> Many - This type of relation means many rows can relate to many other rows.
An example may be labels. You can label many things the same name (desk appliance for example), and each thing can have multiple labels (a lamp can have both desk appliance & light labels).

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So now that you know the different relations, we will go into your question. The relation you are looking at is a one to many, one corporation can have many people, but a person can only have one corporation. I suppose a person could work for multiple people, but that is much more complex (so we'll skip it).

One to many relations are by far the most common, and are pretty easy to do. This is where joins come in (left, right, and inner joins). Tizag has an excellent tutorial on joins here: http://www.tizag.com/sqlTutorial/sqljoin.php .

Hope that helps.

Answer 4

Make your tables look something like this:

Person_ID, Name, Phone, Email, Address, Organisation_ID, Notes (or if you have multiple notes, create a seperate table that maps person_id to a note).

Organisation_ID, Name, Phone, Email, Address, Web, Notes.

Select your person, then if Organisation_ID exists, select the Organisation where Organisation_ID equals the ID you obtained from the person row.