How to show only those sellers who have created at-least one product

I have one sellers table where sellerid column is sno and I have products table where sellerid is sellerid , I want to get those sellers who are not blocked (there is column named flag in sellers table) and have created at least one product so I write this(or maybe copy this)

SELECT e.*, count(*) AS count 
FROM sellers AS e  
left join products AS r ON e.sno = r.sellerid 
where NOT e.flag='1' 
GROUP BY e.sno

Now I do my logic through:

if($row["count"] == 1){
continue;
}

It is producing incorrect result

Answer

-- fake table data
CREATE TABLE sellers SELECT 1 sno, 0 flag UNION SELECT 2, 0 UNION SELECT 3, 0;
CREATE TABLE products SELECT 1 sellerid UNION ALL SELECT 1 UNION ALL SELECT 2;
SET sql_mode := '';

-- initial query
SELECT e.*, count(*) AS `count` 
FROM sellers AS e  
left join products AS r ON e.sno = r.sellerid 
where NOT e.flag='1' 
GROUP BY e.sno

sno	flag	count
1	0	2
2	0	1
3	0	1

-- counting joined values, not rows (NULLs are ignored)
SELECT e.*, count(r.sellerid) AS `count` 
FROM sellers AS e  
left join products AS r ON e.sno = r.sellerid 
where NOT e.flag='1' 
GROUP BY e.sno
-- further filtering by count>0 needed

sno	flag	count
1	0	2
2	0	1
3	0	0

-- join only rows which have matched rows in second table
SELECT e.*, count(*) AS `count` 
FROM sellers AS e  
inner join products AS r ON e.sno = r.sellerid 
where NOT e.flag='1' 
GROUP BY e.sno
-- no further filtering needed

sno	flag	count
1	0	2
2	0	1

db<>fiddle here