MySQL UNION SELECT 3表错误

Question

i am trying to UNION Select 3 Tables: admin_table, moderator_table, user_table.

the three share the same columns: uid, username, password.

here is their contents.

admin_table
uid   |   username   |   password
---------------------------------------
1001  |   admin01    |   lakK4wAsln@ZGK


moderator_table
uid   |   username   |   password
---------------------------------------
2001  |   mod01      |   jb#0NAL837AjLj


user_table
uid   |   username   |   password
---------------------------------------
3001  |    user01    |   sdndLaKn$RfGK:

the problem is when i execute this query:

SELECT * FROM admin_table UNION SELECT * FROM moderator_table UNION SELECT * FROM user_table WHERE username = "admin01";

the result is

uid   |   username   |   password
---------------------------------------
1001  |   admin01    |   lakK4wAsln@ZGK
2001  |   mod01      |   jb#0NAL837AjLj

as you can see the mod01 is appearing whereas my query was to show entries with username being 'admin01' .. i've tried dropping the table and making a new one but it still does the same output. i hope someone can help me out. thanks

Answer 1

The WHERE clause is only applying to the last UNION.

How about this:
SELECT * FROM admin_table WHERE username = "admin01"
UNION
SELECT * FROM moderator_table WHERE username = "admin01"
UNION
SELECT * FROM user_table WHERE username = "admin01"