如何将一个表中的Id与另一个表相关联

Question

i have spent the last 2 days going over this problem trying to work it out.

i have two tables

one is the user_login and it has a row called user_id the other is agedcare and it has a row called id

i have tried to get the 2 to link together

i want to be able to update the agedcare using the id from user_login as the main id

$query = "SELECT id FROM agedcare INNER JOIN user_id ON login_users = login_users.user_id WHERE login_users.user_id = '$id'"

Answer 1

The format is something more like..

SELECT id,name,age 
FROM Table1 
INNER JOIN Table2 
    ON Table1.Field=Table2.Field

Answer 2

Another way to simplify the select statement (so that you avoid using the table names throughout) is to "rename" the table right after you name it. For example, the line that has "FROM Table1 T1" - the T1 immediately after the table name is "renaming" the table allowing you to shorten the table name when you need to refer to it. In addition, you can use the t1 and t2 identifiers when selecting the fields.

SELECT t1.id,t1.name,t2.age FROM Table1 T1 INNER JOIN Table2 T2 ON T1.Field=T2.Field

Answer 3

检查你的加入格式，它必须是这样的

SELECT * FROM t1 as a LEFT JOIN t2 as b ON a.id=b.id where user_id = 'id'