help in uniquely identifying combine columns

How can I uniquely identify two or more columns, that I have used table named address in the database, now address is has fields like street name, suite name and street num.

strnum | strnam | sutname

1 | xyz | 32

1 | xyz | 32

now how can I uniquely these three columns. That is I wa开发者_StackOverflownt to check whether these three column are already inserted or not. If any field valus is changed than its ok, it will insert new one. but in case all three similar field..Help me to combinely identify these three fields.

You do it by adding unique constraint.

ALTER TABLE your_table ADD UNIQUE(strnum, strnam, sutname);

Then you do the following:

INSERT IGNORE INTO your_table (strnum, strnam, sutname) VALUES ('1', 'xyz', 'etc');

If the value exists already - no insert will happen and no errors will be raised (that's what the IGNORE part is).

By the way why do you use such short and vague column names? It's not the DOS era any more, you can be descriptive with your column names.

$query = "SELECT * FROM `address` WHERE `strnum` = '$strnum' AND `strnam` = '$strnam' AND `sutname` = '$sutname' LIMIT 1";
$result = mysql_query($query);
if (!mysql_num_rows($result)) {
    // If you get to here, there is no existing record
    $query = "INSERT INTO `address` (`strnum`,`strnam`,`sutname`) VALUES ('$strnum','$strnam','$sutname')";
    if (!mysql_query($query)) print('Insert failed!');
} else print('Record already exists!');

EDIT I just added a missing ; so this parses...

just add them as unique keys in table structure and you'll not be able to insert two of them

you can do something like this

 SELECT * FROM table WHERE col1 = $something AND col2 = $something2 AND col3 = $something3  

(remember about escpaing php variables) if the record is returned it means it exists. You can also add LIMIT 1 to make it faster.

if your question is about ENSURING that no duplicates occur in the table (for those 3 columns), then probably the best solution is to add UNIQUE index on those three columns.