MySQL Join语句从两个表中获取数据到datagridview

Question

I have two tables that I'm trying to join, 'holidays' and 'users'.

Users contains all my user info, the the column 'id' being primary and unique. Holidays contains a column called 'userid', which corresponds to the id in the user table.

I'm struggling to get the join statement to work... what I'm looking for is the result of the select statement to give me the friendlyname (column 'fname' in user table) instead of giving me the value of userid.

Here's what I'm trying...

 SELECT * FROM holidays JOIN users on users.id=holidays.userid WHERE holidays.status = 0

But i'm not getting a correct result - SQL executes without error, but my DGV is filled with tons of erroneous results.

Apologies If I have not used the correct terminology or whatever. I'm new to the concept of joins.

Here is hopefully a better explanation of what I am after...

Thanks in advance.

Answer 1

You need to select the specific values you want from every table in the JOIN:

SELECT u.fname
FROM holidays h
JOIN users u
ON u.id = h.userid
WHERE h.status = 0

by the alias ( FROM users u ) you can select column from users table by u.fname

Answer 2

First try to right join to the User table. If you just want the fname then select the column name in the SELECT query, as SELECT * takes more time then SELECT column name .