Check if MySQL table exists without using select from syntax?
If you want to be correct, use INFORMATION_SCHEMA.
SELECT *
FROM information_schema.tables
WHERE table_schema = 'yourdb'
AND table_name = 'testtable'
LIMIT 1;
Alternatively, you can use SHOW TABLES
SHOW TABLES LIKE 'yourtable';
If there is a row in the resultset, table exists.
Checking that a table exists on MySQL
Try using the information_schema
to ask if the table exists. Something like
SELECT
*
FROM
information_schema
WHERE TABLE_NAME = "$table_array"
Take a look through everything the information_schema
holds, you will be pleasantly surprised by the information it has stored about your databases :)
Check if a table exists in mysql
You can try this codeigniter function to check table already exist.
if ($this->db->table_exists('tbl_user')) {
// table exists (Your query)
} else {
// table does not exist (Create table query)
}
Check if MySQL table exists or not
Updated mysqli version:
if ($result = $mysqli->query("SHOW TABLES LIKE '".$table."'")) {
if($result->num_rows == 1) {
echo "Table exists";
}
}
else {
echo "Table does not exist";
}
Original mysql version:
if(mysql_num_rows(mysql_query("SHOW TABLES LIKE '".$table."'"))==1)
echo "Table exists";
else echo "Table does not exist";
Referenced from the PHP docs.
MySQL check if a table exists without throwing an exception
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();
How to check a condition whether table exist or not in RMysql
Here's what I do. Maybe there's something else that's more robust or generalizable?
Just "show tables" as a query and check for the presence of your table name in the result.
loadData <- function() {
db <- dbConnect(
MySQL(),
dbname = databaseName,
host = host,
port = port,
user = user,
password = password
)
rs <- dbSendQuery(con, "show tables")
table.frame <- fetch(rs, n = -1)
if ("some_table" %in% table.frame[, 1]) {
res <- dbSendQuery(db, "SELECT * FROM some_table")
final_data <- dbFetch(res)
dbDisconnect(db)
return(final_data)
} else {
return(NULL)
}
}
mysql) select values if table exists
This cannot be achieved using a simple query because MySQL analyses the query as a whole before performing it: it is not a procedural language and the queries are never executed line by line.
To do what you want to do without help of any other language, you must use stored procedures: https://dev.mysql.com/doc/refman/8.0/en/create-procedure.html
So the first step is to add a new FUNCTION in your database that will contain the "if table exists" part (see https://dev.mysql.com/doc/refman/8.0/en/if.html for if statements) and will return the desired value based on the schema, table, and column provided as strings in input of the function.
Then you can use the FUNCTION in any query in your database.
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