Why does MySQL LEFT JOIN not return all rows unless there is WHERE clause - phpMyAdmin issue

Question

Consider the following:

eventTypes table has 163 rows.

events has 43,000 rows.

SELECT events.eventTypeID, eventTypes.eventTypeName 
FROM events 
LEFT JOIN eventTypes ON events.eventTypeID = eventTypes.eventTypeID

This returns 163 rows. However, if I add "WHERE events.eventID >= 0"

SELECT events.eventTypeID, eventTypes.eventTypeName 
FROM events 
LEFT JOIN eventTypes ON events.eventTypeID = eventTypes.eventTypeID 
WHERE events.eventID >= 0

I get all 43,000 rows. I would expect the lack of a WHERE clause would give me everything. Am I thinking about this wrong?

Update: I just tried this on another server and same result. My exact query copied and pasted is:

SELECT events.eventTypeID, eventTypes.eventTypeName FROM events LEFT JOIN eventTypes ON events.eventTypeID = eventTypes.eventTypeID

This only returns the first 163 records. MySQL Versions are 5.5.29 and 5.1.61. I looked in the bug list and found nothing.

Update #2: EXPLAIN gives the same output with either query (ie with or without WHERE 1=1)

mysql> EXPLAIN(SELECT events.eventTypeID, eventTypes.eventTypeName FROM events LEFT JOIN eventTypes ON events.eventTypeID = eventTypes.eventTypeID);
+----+-------------+------------+--------+---------------+-------------+---------+-------------------------------+-------+-------------+
| id | select_type | table      | type   | possible_keys | key         | key_len | ref                           | rows  | Extra       |
+----+-------------+------------+--------+---------------+-------------+---------+-------------------------------+-------+-------------+
|  1 | SIMPLE      | events     | index  | NULL          | eventTypeID | 4       | NULL                          | 37748 | Using index |
|  1 | SIMPLE      | eventTypes | eq_ref | PRIMARY       | PRIMARY     | 4       | casefriend.events.eventTypeID |     1 |             |
+----+-------------+------------+--------+---------------+-------------+---------+-------------------------------+-------+-------------+

Update#3 Testing on a 3rd system produces results I expect though I have no idea why. The 3rd system is another CentOS6 running MySQL 5.1.69. I imported the exact dumps from my development system that I imported into the 2nd test system that did not produce the correct results.

Update#4 Found the issue. This is NOT a MySQL issue. This is a phpMyAdmin issue. When testing on the command line with mysql client I get the correct results on all systems.

Answer 1

I tried this at SqlFiddle: http://sqlfiddle.com/#!2/c9908b/1

create table event (id int,type_id int);
create table type (type_id int, type_name varchar(30));

insert into type values(1, 'type 1');
insert into type values(2, 'type 2');
insert into type values(3, 'type 3');
insert into type values(4, 'type 4');
insert into type values(5, 'type 5');

insert into event values( 1,1);
insert into event values( 2,1);
insert into event values( 3,1);
insert into event values( 4,1);
insert into event values( 5,2);
insert into event values( 6,2);
insert into event values( 7,2);
insert into event values( 8,2);
insert into event values( 9,3);
insert into event values(10,3);
insert into event values(11,3);
insert into event values(12,3);
insert into event values(13,4);
insert into event values(14,4);
insert into event values(15,4);
insert into event values(16,4);
insert into event values(17,5);
insert into event values(18,5);
insert into event values(19,5);
insert into event values(20,5);

select event.id, type.type_name from event left join type
on event.type_id=type.type_id

I get 20 rows back as expected

Answer 2

SELECT events.eventTypeID, eventTypes.eventTypeName 
FROM events 
LEFT JOIN eventTypes ON events.eventTypeID = eventTypes.eventTypeID 
WHERE events.eventID >= 0

Beacuase if you mention ( events.eventID >= 0 ) it means get all those rows they have this condition true and events table has 43000 rows and condition true for all rows and you using LEFT JOIN so you get 43000 rows

Answer 3

I would expect the lack of a WHERE clause would give me everything. 
Am I thinking about this wrong?

Yes , you are right your first query is correct and it should return what you are expecting. You are using LEFT OUTER JOIN , which means all records from left table and matching records from right table.

This is issue is not related to MYSQL version as my knowledge.

My suggestion is ,please check the relation (foreign key and primary key) on which you are joining both table.