PHP/数据库：找出有多少行有内容

Question

I have a SQL-statement like this:

 $stmtTHIS = $db->query("SELECT titel, done_date FROM task WHERE project = $tID ");

How can I find out how many rows have an content in "done_date"?

Answer 1

First you have to define what "have content" means then just write a WHERE clause to find those. And use the COUNT function to count the number of rows returned. So lets say "have content" means the field is not null.

SELECT COUNT(*) FROM task WHERE project = $tID AND done_date IS NOT NULL

This counts all the records with that project id and have a value for done_date.

You may also want to check that done_date does not have some other empty value like empty string or 0.

AND done_date != "" AND done_date !=0

Alternate:

Use the query you have to get all those rows, then do the count in PHP:

 $stmtTHIS = $db->query("SELECT titel, done_date FROM task WHERE project = $tID ");

$count = 0;
while($row = $stmtTHIS->fetchAssoc()){
    //You probably want to do other stiff with the data
    if( !empty($row['done_date']) ){
        $count++;
    }
}
echo $count;

Your code might be slightly different depending on the DB library your using, (I assumed mysqli)