[Resolved] Detect Table Names

BrentNorin

How would I go about checking if a table is in existence? Say for instance someone wants to add pictures with my script and they call it dance. So then the code will have to first check to see if photos_dance exists before it can add photos_dance.

devinemke

which RDBMS are you using? if mysql then use [man]mysql_list_tables[/man]

BrentNorin

Yes mysql and I got what I want, but I don't understand what it is doing.

$query = mysql_list_tables('controll_brent');
while ($row = mysql_fetch_row($query)) {
echo $row[0];
}

How is that outputting every table name? Guess what I'm asking for specifically is what is that while statement doing.

tekky

it returns a result source just like mysql_query() would...

there for you get a collection of data from mysql that for simplicitys sake we'll say looks like this...

Table1|Table2|Table3|Table4 (the | denoting seperation of rows)

now what the while loop does via the mysql_fetch_row is say oke... give me 1 row of data (in this case its 1 table name)

so you get Table1
then it keeps looping until $row is no longer set to a new row of data

so that gives you the final output of

Table1
Table2
Table3
Table4

BrentNorin

Ok I'm not trying to act dumb here, I'm just trying to learn it to the T. I understand it's going through and taking each part of that array and spitting it out, but how does looping $row = array simply manage to separate that data! I could see it if there were something to tell it to move on to the next part of the array, but I dont.

devinemke

Originally posted by BrentNorin
I could see it if there were something to tell it to move on to the next part of the array, but I dont.

[man]mysql_fetch_row[/man] returns an enumerated array for the current row of the result resource that is fed as it's argument. in addition, it also advances the result resouce pointer by 1 row, so when the while loop comes around again it get the next row, and so on. as soon as it reaches the last row it returns boolean FALSE. this is why the while loop ends after the last row. the while is in a sense saying: keep going while the expression evaluates as TRUE and stop when it evealutes FALSE. make sense?

BrentNorin

Absolutely! Thanks. I did not know that it returns a count.