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@NogDogApr 02.2020 — #
Way too much stuff to read here, but that caught my eye as (almost) never correct. It's assigning the number 1 to
https://www.php.net/manual/en/mysqli-stmt.get-result.php#example-1968 @NogDogApr 05.2020 — #
If so, either it was an error, or they were not _comparing_ values but instead were interested if checking if the result of an assignment was "truthy" or "falsey". Something like this saves a line or two of code, though that may be a false savings if it makes the code more difficult to maintain?
@NogDogApr 05.2020 — #
Basically, yes. A single "=" is _not_ a comparison operator, so do not use it if you want to compare if the things on either side of it are equal. That does not mean you can never use it in a conditional expression like in an
How To Check SQL COUNT Equalts To 1 ?
Php Folks,
Doing an Sql query, I am trying to check if a certain email exists or not. Trying to check with the SQL COUNT.
It’s like this …
You see a form asking you for your email. You input your email.
I want php to see if the email exists in the db or not. Check using the COUNT.
If it does exist in mysql db, it means you are already registered. And so here, the the login() function should trigger for you to login.
Else the register() function should trigger so the user’s inputted email gets registered (dumped into the db).
No, the form submit button won’t say “login” or “register” but “submit”.
I don’t want to create 2 different pages or 2 different forms. One for “login” and one for ‘register”.
To cut code short, i want the same form to be able to do both. Login and Register.
So, login() function looks something like this …
[code]
$sql_query = “SELECT id,username,first_name,surname,FROM users WHERE personal_email = ?”;
And register() function looks something like this ..
[code]
$sql_query = “INSERT INTO users (personal_email) VALUES (?)”;
Understand ? Simple. Not rocket science.
Now, at the very beginning, when the user inputs his email, I must get php to check first whether the inputted email exists or not. And then trigger the appropriate function (login/register) based on the result found.
Now, how to check if the email exists in the db or not using the COUNT ?
CODE CONTEXT …
[code]
$sql_query = “SELECT COUNT(personal_email) FROM users WHERE personal_email = ?”;
$stmt = mysqli_prepare($conn,$sql_query);
if($stmt == false)
{
// just for debugging for now:
die(“<pre>Prepare failed:n”.mysqli_error($conn).”n$sql_query</pre>”);
}
else
{
//Bind Variables to the Prepared Statement as parameters.
mysqli_stmt_bind_param($stmt,’s’,$email);
//Attempt to execute the Prepared Statement.
if(!mysqli_stmt_execute($stmt))
{
//Close Connection.
mysqli_close($conn);
die(“Could not mysqli_stmt_execute! Please try again later!”);
}
//mysqli_stmt_bind_result($stmt,$email);
$result = mysqli_stmt_get_result($stmt);
if($sql_query == 1) //This means the COUNT = 1 as email found in db.
{
//$_SESSION[‘session_type’] = ‘account’;
$_SESSION[‘session_type’] = ‘login’;
login();
}
else //This means the COUNT = 0 as email NOT found in db.
{
$_SESSION[‘session_type’] = ‘register’;
register();
}
//Close Statement.
//mysqli_stmt_close($stmt);
//Close Connection.
//mysqli_close($conn);
}
Q1a. Which of the following is correct ?
Q1b. Which of the following correct one would you use over the other(s) and why choose to use that particular one over the other correct one(s) ?
Q1c. Which one is incorrect and why is it incorrect ?
[code]
$sql_query = “SELECT COUNT(personal_email) FROM users WHERE personal_email = ?”;
$stmt = mysqli_prepare($conn,$sql_query);
/*
WHICH OF THE FOLLOWING IFS ARE CORRECT ? OUT OF THE CORRECT ONES, GIVE YOUR RANKINGS. I HAVE RANKED MY ONES BELOW.
*/
if(!$stmt) //Rank 1
if($stmt == false) //Rank 2
if($stmt !== true) //Rank 3.
if(!$stmt == true) //Rank 4.
if($stmt != true) //Rank 5. I think this is incorrect. Let me know if I am write or wrong.
if(!$stmt = true) //Rank 6. I think this is incorrect. Let me know if I am write or wrong.
if($stmt == 0) //Rank 7. I think this is incorrect. Let me know if I am write or wrong.
if($stmt < 1) //Rank 8. I think this is incorrect. Let me know if I am write or wrong.
if($stmt !> 0) //Rank 9. I think this is incorrect. Let me know if I am write or wrong.
if(!$stmt > 0) //Rank 10. I think this is incorrect. Let me know if I am write or wrong.
Q2a. Which of the following is correct ?
Q2b. Which of the following correct one would you use over the other(s) and why choose to use that particular one over the other correct one(s) ?
Q2c. Which one is incorrect and why is it incorrect ?
[code]
/*
WHICH OF THE FOLLOWING IFS ARE CORRECT ? OUT OF THE CORRECT ONES, GIVE YOUR RANKINGS. I HAVE RANKED MY ONES BELOW.
*/
//Bind Variables to the Prepared Statement as parameters.
mysqli_stmt_bind_param($stmt,’s’,$email);
//WHICH OF THE FOLLOWING IFS ARE CORRECT ? OUT OF THE CORRECT ONES, GIVE YOUR RANKINGS. I HAVE RANKED MY ONES BELOW.
if(!mysqli_stmt_execute($stmt)) //Rank 1
if(mysqli_stmt_execute($stmt) == false) //Rank 2
if(mysqli_stmt_execute($stmt) !== true) //Rank 3
if(!mysqli_stmt_execute($stmt) == true) //Rank 4
if(mysqli_stmt_execute($stmt) != true) //Rank 5. I think this is incorrect. Let me know if I am write or wrong.
if(!mysqli_stmt_execute($stmt) = true) //Rank 6. I think this is incorrect. Let me know if I am write or wrong.
{
//Close Connection.
mysqli_close($conn);
die(“Could not mysqli_stmt_execute! Please try again later!”);
}
Q3a. Which of the following is correct ?
Q3b. Which of the following correct one would you use over the other(s) and why choose to use that particular one over the other correct one(s) ?
Q3c. Which one is incorrect and why is it incorrect ?
[code]
//$result = mysqli_stmt_bind_result($stmt,$email);
$result = mysqli_stmt_get_result($stmt);
/*
WHICH OF THE FOLLOWING IFS ARE CORRECT ? OUT OF THE CORRECT ONES, GIVE YOUR RANKINGS. I HAVE RANKED MY ONES BELOW.
*/
if($sql_query = 1)
if(!$sql_query < 1)
if($sql_query > 0)
if($sql_query == 1)
if($sql_query !< 1)
/*
Remember, the $sql_query is doing a COUNT for the found email. If email found in db then COUNT will be 1, else COUNT would be 0.
Eg. $sql_query = “SELECT COUNT(personal_email) FROM users WHERE personal_email = ?”;
*/
{
//$_SESSION[‘session_type’] = ‘account’;
$_SESSION[‘session_type’] = ‘login’;
login();
}
else
{
$_SESSION[‘session_type’] = ‘register’;
register();
}
Q4a. Which of the following is correct ?
Q4b. Which of the following correct one would you use over the other(s) and why choose to use that particular one over the other correct one(s) ?
Q4c. Which one is incorrect and why is it incorrect ?
[code]
//$result = mysqli_stmt_bind_result($stmt,$email);
$result = mysqli_stmt_get_result($stmt);
/*
WHICH OF THE FOLLOWING IFS ARE CORRECT ? OUT OF THE CORRECT ONES, GIVE YOUR RANKINGS. I HAVE RANKED MY ONES BELOW.
*/
if(mysqli_num_rows($result) = 1)
if(!mysqli_num_rows($result) < 1)
if(mysqli_num_rows($result) > 0)
if(mysqli_num_rows($result) == 1)
if(mysqli_num_rows($result) !< 1)
/*
Remember, the $sql_query is doing a COUNT for the found email. If email found in db then COUNT will be 1, else COUNT would be 0.
Eg. $sql_query = “SELECT COUNT(personal_email) FROM users WHERE personal_email = ?”;
*/
{
//$_SESSION[‘session_type’] = ‘account’;
$_SESSION[‘session_type’] = ‘login’;
login();
}
else
{
$_SESSION[‘session_type’] = ‘register’;
register();
}
Q5: Is it true that, to check whether the COUNT is 1 or 0, I should not be checking like any of the following …
[code]
if($sql_query = 1)
[code]
if($sql_query == 1)
But should be checking like one of the following…
[code]
if(mysqli_num_rows($result) = 1)
[code]
if(mysqli_num_rows($result) == 1)
[code]
if($result = 1)
[code]
if($result == 1)
Yes or no ? Answer this.
I am just experimenting. That is all.
Show me how to use the …
[code]
“if($sql_query ..”
….. to check if the COUNT is 1 or 0.
Look at Q3 above. That question is most important as I am stuck there. Things go wrong there. When I check for an email that exists in the db, naturally the login() function should trigger but instead the register() function triggers. That is why I know I am doing something wrong here. Concentrate on teaching me the answer to Q4 and I should be able to take it from there.
Q6. To get the email COUNT with the SQL query, which of the following should I use ?
[code]
$result = mysqli_stmt_bind_result($stmt,$email);
[code]
$result = mysqli_stmt_get_result($stmt);
Thanks!
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0
@NogDogApr 02.2020 — #>@developer_web#1616873 if($result = 1)
Way too much stuff to read here, but that caught my eye as (almost) never correct. It's assigning the number 1 to
$resultif()$result0
@NogDogApr 02.2020 — #>@developer_web#1616881 What do you mean
=if($something = 1)0
@NogDogApr 02.2020 — #PS: Neither A nor B will work, since you never actually execute the query. Take a look at Example #2 for the full process: 0
@NogDogApr 05.2020 — #>@developer_web#1616987 I have seen people using the "=" to compare values
If so, either it was an error, or they were not _comparing_ values but instead were interested if checking if the result of an assignment was "truthy" or "falsey". Something like this saves a line or two of code, though that may be a false savings if it makes the code more difficult to maintain?
<i>
</i>if($myArray = json_decode($jsonString, 1)) {
// do stuff with $myArray
}
else { // json_decode() returned false or empty string
throw new Exception("Invalid json: '$jsonString')");
}
0
@NogDogApr 05.2020 — #>@developer_web#1617012 So you are saying, if I use the IF to compare some value then I must always use the "==" sign within the if brackets. using the "=" is pointless here.
Basically, yes. A single "=" is _not_ a comparison operator, so do not use it if you want to compare if the things on either side of it are equal. That does not mean you can never use it in a conditional expression like in an
if()