mysql count num rows code example

Example 1: mysql get count of rows

SELECT COUNT(*) FROM my_table;
SELECT COUNT(*) FROM my_table WHERE my_column IS NULL;
SELECT COUNT(*) FROM my_table WHERE my_column = 'my_value';
SELECT COUNT(DISTINCT tel) gender_count,
       COUNT(DISTINCT CASE WHEN gender = 'male'   THEN tel END) male_count,
       COUNT(DISTINCT CASE WHEN gender = 'female' THEN tel END) female_count
FROM people;

Example 2: mysql num rows

//number of rows retrieved from a query
<?php

$link = mysql_connect("localhost", "mysql_user", "mysql_password");
mysql_select_db("database", $link);

$result = mysql_query("SELECT * FROM table1", $link);
$num_rows = mysql_num_rows($result);

echo "$num_rows Rows\n";

?>

Example 3: mysql count table rows

select table_name, sum(table_rows) as sum 
from information_schema.tables
where table_schema = '[DB NAME]'
group by table_name 
order by sum desc;

Example 4: mysql select count if contains

SELECT sum( case when `tags_Column` CONTAINS 'tag2' then 1 else 0 end ) as tag2,
       sum( case when `tags_Column` CONTAINS 'tag3' then 1 else 0 end ) as tag3,
       .....
       sum( case when `tags_Column` CONTAINS 'tag256' then 1 else 0 end ) as tag256,
       sum( case when `tags_Column` CONTAINS `tag2` OR 
                      `tags_Column` CONTAINS 'tag3`
            then 0 else 1 end ) as doesnt_contains_tags_2_3
FROM `TableContainsTags`