How is it possible to select the first column in the Where clause. I am trying to make a php function to retrieve table data based on the id, yet since the titles of the id columns are different in various tables, I need to refer to the first column in the Where clause as the first column is always the id column.
The scenario would be something like the following, but it throws errors and says that there is an error in the SQL syntax.
$stmt = $this->conn->prepare("SELECT * FROM $table WHERE column(1) = :id");
Thanks in advance.
I don't think there's a built-in way to do this. But you can query INFORMATION_SCHEMA.COLUMNS to get the column names.
$col_stmt = $this->conn->prepare("
SELECT column_name
FROM information_schema.columns
WHERE table_schema = DATABASE()
AND ordinal_position = 1
AND table_name = :table");
$col_stmt->execute([':table' => $table]);
$first_col = $col_stmt->fetchColumn();
$stmt = $this->conn->prepare("SELECT * FROM `$table` WHERE `$first_col` = :id");
Since there is no built-in way to do this, I came up with the following code block to get the first column and then use it in my SELECT statements.
$stmt = $this->conn->query("SHOW columns FROM $table");
return $stmt->fetch(PDO::FETCH_LAZY)[0];
I think this strategy is a bit shorter than Barmar's, though his is completely right and to the point.
Related
Ok, don't know if this is simple in practice as it is in theory but I want to know.
I have a single INSERT query were by in that query, i want to extract the AUTO_INCREMENT value then reuse it in the same query.
For example
//values to be inserted in database table
$a_name = $mysqli->real_escape_string($_POST['a_name']);
$details = $mysqli->real_escape_string($_POST['details']);
$display_type = $mysqli->real_escape_string($_POST['display_type']);
$getId = mysqli_insert_id();
//MySqli Insert Query
$insert_row = $mysqli->query("INSERT INTO articles (a_name,details,display_type,date_posted) VALUES('$a_name','$details','$display_type$getId',CURRENT_TIMESTAMP)");
Apparently, am getting a blank value(I know because the mysqli_insert_id() is before the query, but I've tried all i could but nothing has come out as i want. Can some please help me on how to achive this
From my knoweldge this cant be done. Because no query has been run, MySQL is unable to return the ID of said query.
You could use a classic approach, pull the id of the previous record and add 1 to it, this is not a great solution as if a record is deleted, the auto increment value and the last value +1 may differ.
Run multiple queries and then use the insert_id (MySQLi is different to what you are using, you are best using $db->lastInsertId(); as mentioned in the comments.
Run a query before hand and store it as a variable;
SELECT auto_increment FROM INFORMATION_SCHEMA.TABLES WHERE table_name = 'tablename'
I strongly recommend Option 2, it is simply the cleanest and most reliable method for what you are looking to achieve.
It seems the value required for $display_type is :$display_type + (max(id) + 1).
In order to get the max_id you'll have to do this query before :
$sql = "SELECT id FROM articles ORDER BY id DESC LIMIT 1";
$result = mysqli->query($sql);
$maxid = $result->fetch_array(MYSQLI_NUM);
// $maxid[0] will contains the value desired
// Remove the mysqli_insert_id() call - Swap $getid by ($maxid[0] + 1)
// and u're good to go
N.B. update the name of ur primary key in the query $sql.
EDIT :
Assuming the weakness of the query and the quick resarch i did.
Try to replace $sql by (don't forget to Update DatabaseName & TableName values) :
$sql = SELECT `AUTO_INCREMENT`
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'DatabaseName'
AND TABLE_NAME = 'TableName';
That Should do it . More info on the link below :
Stackoverflow : get auto-inc value
I don't think this can be done. You'll have to first insert the row, then update display_type, in two separate queries.
Thanks guys for your opinions, out of final copy, paste, edit and fix; here is the final working code(solution)
`
//values to be inserted in database table
$a_name = $mysqli->real_escape_string($_POST['a_name']);
$details = $mysqli->real_escape_string($_POST['details']);
$display_type = $mysqli->real_escape_string($_POST['display_type']);
//Select AUTO_INCREMENT VALUE
$sql = "SELECT `AUTO_INCREMENT`
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = 'chisel_bk'
AND TABLE_NAME = 'articles'";
$result = $mysqli->query($sql);
$maxid = $result->fetch_array(MYSQLI_NUM);
$getId = $maxid[0];
//MySqli Insert Query
$insert_row = $mysqli->query("INSERT INTO articles (a_name,details,display_type,date_posted) VALUES('$a_name','$details','$display_type$getId',CURRENT_TIMESTAMP)");
This happens to do the magic!!!
`
I have this query
$query = "Select * FROM table WHERE table.firs_column = 1;
Select * FROM table WHERE table.second_column = 1;
Select * FROM table WHERE table.third_column = 1;
Select * FROM table WHERE table.column = 1";
$stmt = $db->prepare($query);
$result = $stmt->execute();
I want to have multiple results, each one have the result of one query!
how to do it?
It looks like you are using PDO, so you could do something like:
$first_set = $stmt->fetchAll(PDO::FETCH_ASSOC);
$stmt->nextRowset();
$second_set = $stmt->fetchAll(PDO::FETCH_ASSOC);
$stmt->nextRowset();
$third_set = $stmt->fetchAll(PDO::FETCH_ASSOC);
$stmt->nextRowset();
$fourth_set = $stmt->fetchAll(PDO::FETCH_ASSOC);
To get your 4 rowsets.
You can use UNION if table is same for your multiple queries
Select * FROM table WHERE table.firs_column = 1
UNION
Select * FROM table WHERE table.second_column = 1
UNION
Select * FROM table WHERE table.third_column = 1
UNION
Select * FROM table WHERE table.column = 1
After you finish with the first result set, use nextRowset() method to advance to the next result set.
You need to have a PHP MySQL driver extension that supports this method.
Not sure what you're aiming at, but did you try UNION?
Your SQL statement would look like this:
SELECT * FROM table WHERE table.firs_column = 1
UNION
SELECT * FROM table WHERE table.second_column = 1
UNION
SELECT * FROM table WHERE table.third_column = 1
UNION
SELECT * FROM table WHERE table.column = 1;
Please show your desired result if you think of something different.
Since we don't know anything about your database structure, I suggest looking into mysqli::multi_query().
If you're trying to pull related data, I highly suggest you look into doing MySQL JOINs instead. MySQL is another language unto itself that should be learned as a distinct language rather than just a string to be contatenated in PHP.
I am trying to do a query in PHP PDO where it will grab a simple result. So like in my query I need it to find the row where the column group is 'Admin' and show what ever is in the group column. I know that we already know what it should be [Should be admin] but just need to get the query to work. Its only grabbing 1 row from my table, so will I need forsearch?
If I change WHERE group = 'Admin' to WHERE id = '1' it works fine. But I need it so it can be where group = 'admin'
$sql2 = "SELECT * FROM groups WHERE group = 'Admin'";
$stm2 = $dbh->prepare($sql2);
$stm2->execute();
$users2 = $stm2->fetchAll();
foreach ($users2 as $row2) {
print ' '. $row2["group"] .' ';
}
Thanks
group is a reserved word in MySQL, that's why it's not working. In general it's a bad idea to use reserved words for your column and table names.
Try using backticks around group in your query to get around this, so:
$sql2 = "SELECT * FROM groups WHERE `group` = 'Admin'";
Also you should really use placeholders for values, because you're already using prepared statement it's a small change.
Edit: just to clarify my last remark about the placeholders. I mean something like this:
$sql2 = "SELECT * FROM groups WHERE `group` = ?";
$stm2->execute(array('Admin'));
try to use wildcard in your WHERE Clause:
$sql2 = "SELECT * FROM groups WHERE group LIKE '%Admin%'";
Since the value in your table is not really Admin but Administrator then using LIKE and wildcard would search the records which contains admin.
$select = $_POST['select'];
$search = $_POST['search'];
$sql = "SELECT * FROM '$select' WHERE $select = '$search'";
I have 2 variables carrying the aforementioned table name and column name. I want the user to be able to select a table name and then select a specific column and output the requested record.
I only have a problem with writing the sql statement. Thanks in advanced!
you may use the following query without any problem...
$sql="SELECT * from $select WHERE field_name='$search' ";
In the above query field_name is the that field name in which you want to search value of mattch the value.
you are using table instead of column
$sql = "SELECT * FROM '$select' WHERE $select = '$search'";
^^^^^^----//this should be column not table
this is bad idea you are doing. FULL of sql injection
switch to pdo or mysqli.
Escape your variables.
I can't seem to find or write a sqlquery that SELECTS the DEFAULT VALUE
(and I don't think I can generate it in phpmyadmin for me to copy)
I tried to SELECT it as if it was a record but to no avail...
$defaultValue_find = mysql_query(
"SELECT $group FROM grouptable WHERE $group='DEFAULT'")
or die("Query failed:".mysql_error());
$defaultValue_fetch = mysql_fetch_row($defaultValue_find);
$defaultValue = $defaultValue_fetch[0];
echo $defaultValue;
"SELECT $group FROM grouptable WHERE $group=DEFAULT( $group ) "
Or I think better:
"SELECT DEFAULT( $group ) FROM grouptable LIMIT 1 "
Update - correction
As #Jeff Caron pointed, the above will only work if there is at least 1 row in grouptable. If you want the result even if the grouptable has no rows, you can use this:
"SELECT DEFAULT( $group )
FROM (SELECT 1) AS dummy
LEFT JOIN grouptable
ON True
LIMIT 1 ;"
Get the default values of all fields in mytable in the associative array $res:
// MySQL v.5.7+
$res = [];
$sql = "SHOW FULL COLUMNS FROM `mytable`";
foreach ($PDO->query( $sql, PDO::FETCH_ASSOC ) as $row) {
$res[$row['Field']] = $row['Default'] ;
}
print_r($res);
You can get the default column of any table, and in fact lots of interesting information about it, by looking at the INFORMATION_SCHEMA.COLUMNS tables. As the documentation states...
INFORMATION_SCHEMA provides access to database metadata, information about the MySQL server such as the name of a database or table, the data type of a column, or access privileges. (Source: MySQL 8.0 Reference Manual / INFORMATION_SCHEMA Tables / Introduction.)
So, to get the column default, just SELECT COLUMN_DEFAULT, like...
SELECT COLUMN_DEFAULT
FROM information_schema.columns
WHERE TABLE_SCHEMA = 'YourSchema'
AND TABLE_NAME = 'YourTable' AND
COLUMN_NAME = 'YourField';
You can then just wrap this into a subquery, SELECT * FROM YourTable WHERE YourField = (queryabove). This lets you make a much more customizable, default-based list in your MySQL query.