I have a script that geocodes physical addresses and puts it into a MySQL database with two columns: coord_lat and coord_long. These are float type columns but unfortunately some addresses don't get geocoded correctly and the script tries to push the address as a null value into the database which then breaks the script because the database cannot hold a null value.
I'm trying to find a way I can rewrite my script to determine if the geocoded address comes out to a null value to automatically rewrite that value to 0 so that the database and script don't break.
Can anyone give me some advice on switching/replacing a null values to 0?
try this:
if PHP (shorthand if)
(is_null($value) ? 0:$value)
else if MySQL (coalesce function)
SELECT COALESCE(#your_value_here,0) FROM dual
for reference of coalesce:
http://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html
for shorthand if statement (ternary):http://davidwalsh.name/php-ternary-examples
If the value is NULL, then assign 0
if(is_null($value)){
$value = 0;
}
Related
I have a simple MySQLi statement with bound results. One of the fields in that recordset is a double and results can be either NULL, 0 or other numeric value.
$wheels_cost is the recordset bound result.
The following logic should ignore null values and only process zero or other numeric values.
if($wheels_cost <> NULL){
carry out a process
} else {
the value is null so ignore
}
For some reason, the results I'm getting seem to reflect that the result is a zero rather than a null - which is not the desired result.
I've checked the DB and the field is null.
I need to tell the difference between a null and a zero value.
I've only tried the above logic and can't think why it doesn't work. Should I be using isset() or is_null() or empty()?
Thanks for feedback
Finished code below:
if(!is_null($wheels_cost)){
carry out a process
} else {
the value is null so ignore
}
Worked perfectly
Try this:
if($wheels_cost is not NULL){
# carry out a process
} else {
# the value is null so ignore
}
I do not use mySQLi but I think the syntax should look like PostGreSQL
In PostGreSQL, the NULL value can not be equal or differentiated to any column or variable, since it is an unknown value and of an unknown type.
Examples here: https://www.techonthenet.com/mysql/is_null.php
I have a table with the column data type like this:
price decimal(6,2) unsigned NOT NULL,
And my validation code is like this:
if ( (!empty($_POST['price'])) && (is_numeric($_POST['price'])) && (isset($_POST['price'])) > 0 ) {
$price = ($_POST['price']);
} else{
$price = FALSE;
echo '<p> Only accept number and must be higher than zero</p>';
}
I use the $_POST form for users to submit the value. But you know,
1/ When the user types any non-numeric value such as a,b,c etc, it also validates well.
2/ When the user types the value zero in, it validates well too.
However, the question is that when I tested it with no value typed in. I mean that I left the value empty and hit the 'submit' button, the error message still returned as per the }else { part does, but the value was still inserted into the table column with a value of 0.00 technically at the same time.
To my limited knowledge, I can guess that the problem was probably at the Mysqli data type of the table I chose, but i don't know how to correct it.
Can you help me, please?
I think the solution you're looking for is to simply move the inserting code to the first if statement. That way it'll only insert the value if it is numeric and not empty.
What you describe means that you've failed to stop the insert when $price===false
(i.e. the problem is not the evaluation; it has given you the correct message. You've some programming logic error elsewhere)
I have searched the site and although I have found questions and answers similar I haven't been able to find an answer. After 4 hours of searching I've decided to bite the bullet and ask the question.
I have 4 date fields in a form that aren't required. I would like it to enter a date into the database if one of the fields has an entry or null if any are left blank.
I have an if statement that checks if the value is empty and if so $value = null, otherwise use $value = date("Y-m-d",strtotime($_post['value'])) to convert it to a date and this works well.
The problem is in my query. If I use '$value' it will insert the date correctly but won't insert a null value because using 'null' makes sql think it's a string. If I use just $value the null inserts just fine but the date goes in as 0000-00-00.
Any advice would be very much appreciated
Thanks for the advice so far...
Null is allowed, this is my script...
if(empty($_POST['fp32_original_install_date'])){
$fp32_install = NULL;
}else{
$fp32_install = date("Y-m-d",strtotime($_POST['fp32_original_install_date']));
}
$sql = "INSERT INTO accounts_cstm (id_c, support_c, install_date_c, sware_renewal_date_c, product_key_c, account_status_c, fp32_support_type_c, fp32_support_renewal_date_c, fp32_original_install_date_c) VALUES ('$Guid','$cdr_support', '$cdr_install', '$cdr_renew', '$prod_key', '$account_status', '$fp32_support', '$fp32_renew', $fp32_install)";
If I use in the query $fp32_install a null value goes in just fine but a date goes in as 0000-00-00, if I use '$fp32_install' the date goes in fine but a NULL value goes in as 1970-01-01 (probably because it sees 'NULL' as a string)
If I echo $fp32_install the value is shown as 2012-08-16 and the SQL type for the column is date and the default is NULL
If you are using posted values from a form, then $_POST['value'] will not be NULL.
You should check for empty values instead.
if($_POST['value']=="")
{
$value="NULL";
}
else
{
$value="'".date("Y-m-d",strtotime($_POST['value']))."'";
}
From the behavior you describe, it sounds as if your DATE column is defined with a DEFAULT 0 clause, or you are providing an invalid value.
According to the MySQL documentation:
<snip>
Invalid DATE, DATETIME, or TIMESTAMP values are converted to the “zero” value of the appropriate type ('0000-00-00' or '0000-00-00 00:00:00').
</snip>
It's difficult to diagnose the exact problem without seeing example code. As a starter, I suggest you try echoing out the SQL statement that is being sent to the database.
I have a strong suspicion that the value for the DATE column is going to appear with quotes around it, a string value of 'NULL', rather than the bare keyword NULL.
I have a if NULL echo "Message" else $value.
There is some JavaScript hiding the input field, so they check it and enter the value.
If they don't check it to enter the field, the db enters 0.00 and doesn't specify NULL so my PHP if statement works.
How do I either set the variable as NULL if its blank, or set NULL in the INSERT statement?
`myTableField` decimal(10,2) default NULL,
Not sure exactly what you're after, but you can run the below if statement to check what value was entered, and set to null accordingly:
if(!is_numeric($fieldvalue) || $fieldvalue==0){
// if the entered value isnt a number (i.e. isnt entered, or invalid) or if the value is zero, sounded like it was your default
$fieldvalue=NULL;
// could also use unset($fieldvalue);
}
If the variable $fieldvalue is set to null (or un-set), it will be inserted as a NULL in your DB according to your field definitions. Make sure your insert statement references the value without ' or " encapsulating figures however (not needed as its a decimal field).
I have a MYSQL table with an ENUM field named "offset" and some other columns. The field is defined as:
ENUM(0,1), can be NULL, predefined value NULL
Now I have two server. A production server and a development server and the same PHP script used to create and to update the database.
First step: the application create the record witout passing the "offset" in the CREATE query.
Second step: the application ask to the user some data (not the "offset" value), read the row inserted in step one and make an array, update some field (not the "offset" field), create a query in an automated fashion and save the row again with the updated values.
The automated query builder simple read all the field passed in an array and create the UPDATE string.
In both systems I obtain this array:
$values = array(... 'offset' => null);
and convert it in this same query passing the values in the mysql_real_escape_string:
UPDATE MyTable SET values..., `offset` = '' WHERE id = '10';
Now there is the problem. When i launch the query in the production system, the row is saved, in the development system I got an error and the db says that the offset data is wrong without saving the row.
From phpmyadmin when I create the row with the first step, it shows NULL in the offset field. After saving the field in the system which give no errors, it show me an empty string.
Both system are using MySQL 5 but the production uses 5.0.51 on Linux and development use 5.0.37 on Windows.
The questions:
Why one system give me an error an the other one save the field ? Is a configuration difference ?
Why when I save the field which is an enum "0" or "1" it saves "" and not NULL ?
Why one system give me an error an the other one save the field ? Is a configuration difference ?
Probably. See below.
Why when I save the field which is an enum "0" or "1" it saves "" and not NULL ?
According to the MySQL ENUM documentation:
The value may also be the empty string ('') or NULL under certain circumstances:
If you insert an invalid value into an ENUM (that is, a string not present in the list of permitted values), the empty string is inserted instead as a special error value. This string can be distinguished from a "normal" empty string by the fact that this string has the numeric value 0. ...
If strict SQL mode is enabled, attempts to insert invalid ENUM values result in an error.
(Emphasis added.)
strager's answer seems like a good explanation on why your code behaves differently on the 2 environments.
The problem lies elsewhere though. If you want to set a value to NULL in the query you shound use exactly NULL, but you are using mysql_real_escape_string() which result is always a string:
$ php -r 'var_dump(mysql_real_escape_string(null));'
string(0) ""
You should handle this differently. E.g:
$value = null
$escaped_value = is_null($value) ? "NULL" : mysql_real_escape_string($value);
var_dump($escaped_value);
// NULL
Some DB layers, like PDO, handle this just fine for you.
If you want it to be NULL, why don't you do this in the first place:
UPDATE MyTable SET values..., `offset` = NULL WHERE id = 10;