Mysql WHERE子句帮助

How can I use a WHERE MySQL clause in a statement which can fetch me all the records? I am settings the WHERE condition conditionally. Like...

if (this) {
    $mycondition=1;
} elseif (that {
    $mycondition=????
}

'SELECT * FROM table WHERE category='.$mycondition

What should be the value of ???? so that when I pass it to the sql statement it fetches me all the records. I was thinking that WHERE category='*' might work but it does not.

You could just use this

if(this){
   $mycondition=" category=1";
}elseif(that{
   $mycondition= " 1"; //1 = 'true'. You could also use "1=1
}

'SELECT * FROM table WHERE '.$mycondition

You need to build your WHERE condition piece by piece :

• start with an empty array
• add some conditions depending on search form input (like add "category=1" or "name like ...")
• implode( " AND ", $array ) will stick the conditions together
• concatenate this in your SQL
• if there is no condition, don't put a where clause

The best answer is not to have a WHERE clause at all, as suggested as part of peufeu's answer if you don't have a condition to be met:

SELECT * FROM table;

Is perfectly valid.

However, if you are in a situation where you must have a WHERE clause (or where it's drastically easier to have one), do as Nanne suggests, and put an "always true" condition as your first clause, so something like:

$query = 'SELECT * FROM TABLE WHERE true';
if (this) {
    $query = $query . ' AND column=this';
}