如何根据MySQL表格单元格的值进行IF语句？

Question

How can I do an if statement based on the value of a mysql table cell. For example, I have a table of people with a column called marital_status. This column has one of two values: yes or no. But this doesn't work:

$query = mysql_query("SELECT marital_status FROM people WHERE first_name = 'John'");

while ($row = mysql_fetch_assoc($query)) {

     $maritalStatus = $row['marital_status'];

}

if ($maritalStatus == "yes") {
   echo "This person is married.";
}
else {
   echo "This person is NOT married.";
}

$maritalStatus == "yes" doesn't return as true even though that is exactly the value in that cell.

Answer 1

If you want to work on each line of data returned by your SQL query, you should place your condition inside the while loop -- which iterates over the lines returned by the excution of the query :

$query = mysql_query("SELECT marital_status FROM people WHERE first_name = 'John'");

while ($row = mysql_fetch_assoc($query)) {
    $maritalStatus = $row['marital_status'];
    if ($maritalStatus == "yes") {
       echo "This person is married.";
    }
    else {
       echo "This person is NOT married.";
    }
}

If this doesn't help, it could be useful to check :

• If the query actually returns results
• If those results are actually what you think they are.

This can be done using var_dump, to dump the content of a variable. For example, in your situation, you could use :

$query = mysql_query("SELECT marital_status FROM people WHERE first_name = 'John'");
while ($row = mysql_fetch_assoc($query)) {
    var_dump($row);     // Will display the content of $row
}

---

As a sidenote, you said in a comment that echoing $maritalStatus gets you "Yes".

If there is a Y in uppercase in your database, that's the reason why your code fails : you are testing for "yes" in lowercase.

In PHP, using the == operator for string comparisons, uppercase letters and lowercase letters are considered as different characters.

If you want to compare in a case-insensitive manner, you'll have to either :

• Convert all strings to the same case (upper or lower, up to you to choose)
  • see strtolower or strtoupper
  • or mb_strtolower / mb_strtoupper if using a multi-byte encoding, such as UTF-8
• Use a case-insensitive comparison function, such as strcasecmp