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In DB I have a table with a field called fk_ownerID. By default, when I add a new table row, the fk_ownerID is empty. In Toad for MySQL, this is shown as {null}. If fk_ownerID is given a value, and I later remove this value, I set fk_ownerID = "".
Now, I have the following code:
$result = $dal->getRowByValue('tableName','id', $_POST['myID']); // Check to see if any rows where returned if (mysql_num_rows($result) > 0) { while ($row = mysql_fetch_array($result)) { $ownerID = $row["fk_ownerID"]; } } Now the variable $ownerID should have a number, or not. But I'm unsure how to check this. Currently I'm doing this:
if ( (strlen($ownerID) == 0) || ($ownerID == '0') || ($ownerID == 'null') ) But I'm pretty sure only one of these tests should be necessary.
What is the best way to check if a row field is empty or null?
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The IS NULL constraint can be used whenever the column is empty and the symbol ( ' ') is used when there is empty value. mysql> SELECT * FROM ColumnValueNullDemo WHERE ColumnName IS NULL OR ColumnName = ' '; After executing the above query, the output obtained is.
To look for NULL values, you must use the IS NULL test. The following statements show how to find the NULL phone number and the empty phone number: mysql> SELECT * FROM my_table WHERE phone IS NULL; mysql> SELECT * FROM my_table WHERE phone = ''; See Section 3.3.
Checks if the value is null, empty, or contains only whitespace characters. Returns true if the string is null, empty, or only whitespace.
Use empty() and/or is_null()
http://www.php.net/empty http://www.php.net/is_null
Empty alone will achieve your current usage, is_null would just make more control possible if you wanted to distinguish between a field that is null and a field that is empty.
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