I have a table with two columns:
ID1 | ID2
---------
1 | A
3 | V
1 | C
4 | B
5 | Q
1 | S
And I want to be 开发者_开发问答able to find out if any row has, say ID1 = 5 and ID2 = Q , and return a true / false value.
Yes, Of course
SELECT * FROM table where ID1='5' and ID2='Q'
PHP (I am just guessing this backend)
$query = "SELECT * FROM table where ID1='5' and ID2='Q'";
$result = mysql_query($query);
if(mysql_num_rows($result)) { return true; }
else { return false; }
1
means TRUE
for mysql
SELECT 1
FROM your_table
WHERE ID1 = 5 AND ID2 = 'Q'
for example this?
SELECT 1
FROM TABLE
WHERE ID1 = 5 AND ID2 = 'Q'
Efficient query for your purpose (faster than other examples):
SELECT 1 FROM table where ID1='5' and ID2='Q' LIMIT 1
PHP sample:
<?php
$query = "SELECT 1 FROM table where ID1='5' and ID2='Q' LIMIT 1";
echo bool(mysql_num_row(mysql_query($query)));
?>
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