how to confirm the table exist before select in mysql [duplicate] - mysql

Question

What is the best way to check if a table exists in MySQL (preferably via PDO in PHP) without throwing an exception. I do not feel like parsing the results of "SHOW TABLES LIKE" et cetera. There must be some sort of boolean query?

Answer 1

Querying the information_schema database using prepared statement looks like the most reliable and secure solution.
$sql = "SELECT 1 FROM information_schema.tables
WHERE table_schema = database() AND table_name = ?";
$stmt = $pdo->prepare($sql);
$stmt->execute([$tableName]);
$exists = (bool)$stmt->fetchColumn();

Answer 2

If you're using MySQL 5.0 and later, you could try:
SELECT COUNT(*)
FROM information_schema.tables
WHERE table_schema = '[database name]'
AND table_name = '[table name]';
Any results indicate the table exists.
From: http://www.electrictoolbox.com/check-if-mysql-table-exists/

Answer 3

Using mysqli I've created following function. Assuming you have an mysqli instance called $con.
function table_exist($con, $table){
$table = $con->real_escape_string($table);
$sql = "show tables like '".$table."'";
$res = $con->query($sql);
return ($res->num_rows > 0);
}
Hope it helps.
Warning: as sugested by #jcaron this function could be vulnerable to sqlinjection attacs, so make sure your $table var is clean or even better use parameterised queries.

Answer 4

This is posted simply if anyone comes looking for this question. Even though its been answered a bit. Some of the replies make it more complex than it needed to be.
For mysql* I used :
if (mysqli_num_rows(
mysqli_query(
$con,"SHOW TABLES LIKE '" . $table . "'")
) > 0
or die ("No table set")
){
In PDO I used:
if ($con->query(
"SHOW TABLES LIKE '" . $table . "'"
)->rowCount() > 0
or die("No table set")
){
With this I just push the else condition into or. And for my needs I only simply need die. Though you can set or to other things. Some might prefer the if/ else if/else. Which is then to remove or and then supply if/else if/else.

Answer 5

Here is the my solution that I prefer when using stored procedures. Custom mysql function for check the table exists in current database.
delimiter $$
CREATE FUNCTION TABLE_EXISTS(_table_name VARCHAR(45))
RETURNS BOOLEAN
DETERMINISTIC READS SQL DATA
BEGIN
DECLARE _exists TINYINT(1) DEFAULT 0;
SELECT COUNT(*) INTO _exists
FROM information_schema.tables
WHERE table_schema = DATABASE()
AND table_name = _table_name;
RETURN _exists;
END$$
SELECT TABLE_EXISTS('you_table_name') as _exists

Answer 6

As a "Show tables" might be slow on larger databases, I recommend using "DESCRIBE " and check if you get true/false as a result
$tableExists = mysqli_query("DESCRIBE `myTable`");

Answer 7

$q = "SHOW TABLES";
$res = mysql_query($q, $con);
if ($res)
while ( $row = mysql_fetch_array($res, MYSQL_ASSOC) )
{
foreach( $row as $key => $value )
{
if ( $value = BTABLE ) // BTABLE IS A DEFINED NAME OF TABLE
echo "exist";
else
echo "not exist";
}
}

Answer 8

Zend framework
public function verifyTablesExists($tablesName)
{
$db = $this->getDefaultAdapter();
$config_db = $db->getConfig();
$sql = "SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = '{$config_db['dbname']}' AND table_name = '{$tablesName}'";
$result = $db->fetchRow($sql);
return $result;
}

Answer 9

If the reason for wanting to do this is is conditional table creation, then 'CREATE TABLE IF NOT EXISTS' seems ideal for the job. Until I discovered this, I used the 'DESCRIBE' method above. More info here: MySQL "CREATE TABLE IF NOT EXISTS" -> Error 1050

Answer 10

Why you make it so hard to understand?
function table_exist($table){
$pTableExist = mysql_query("show tables like '".$table."'");
if ($rTableExist = mysql_fetch_array($pTableExist)) {
return "Yes";
}else{
return "No";
}
}