using variables to name a column in MySQLi table - mysqli

Question

I am trying to create a table on the MySQLi server using input from user. This means some of the columns' names will be determined by the user input. These input can even be "" if the user does not want it. Hence nu of table columns will vary. I am finding it difficult to achieve this. My code is as follows:
<?php
$name = test_input($_POST["name"]);
$prj = test_input($_POST["project"]);
$recipe1 = test_input($_POST["recipe1"]);
$recipe2 = test_input($_POST["recipe2"]);
$recipe3 = test_input($_POST["recipe3"]);
$recipe4 = test_input($_POST["recipe4"]);
$tblname = test_input($_POST["prjtitle"]);
$tableExists = mysqli_query($conn, "DESCRIBE $tblname");
if (TRUE) {
$sql = "CREATE TABLE $tblname (
id INT(4) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
$name VARCHAR(15) NOT NULL,
$prj VARCHAR(15) NOT NULL,
$recipe1 VARCHAR(10) NOT NULL,
$recipe2 VARCHAR(10) NULL,
$recipe3 VARCHAR(10) NULL,
$recipe4 VARCHAR(10) NULL,
reg_date TIMESTAMP
)";
if (mysqli_query($conn, $sql)) {
echo "Table " .$tblname. " created successfully";
} else {
echo "Error creating table: " . mysqli_error($conn);
}
}
mysqli_close($conn);
?>
Note that $recipe2, $recipe3, $recipe4 can have a value "" This means the user does not need the column & as such the column should not be create.
How can I correct above syntax?

Answer 1

You should check it one by one.
$userColumn = ($recipe1 == "" ? "" : $recipe1." VARCHAR(10) NOT NULL,");
$userColumn += ($recipe2 == "" ? "" : $recipe2." VARCHAR(10) NULL,");
$userColumn += ($recipe3 == "" ? "" : $recipe3." VARCHAR(10) NULL,");
$userColumn += ($recipe4 == "" ? "" : $recipe4." VARCHAR(10) NULL,");
then change if statement from
if (TRUE) {
$sql = "CREATE TABLE $tblname (
id INT(4) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
$name VARCHAR(15) NOT NULL,
$prj VARCHAR(15) NOT NULL,
$recipe1 VARCHAR(10) NOT NULL,
$recipe2 VARCHAR(10) NULL,
$recipe3 VARCHAR(10) NULL,
$recipe4 VARCHAR(10) NULL,
reg_date TIMESTAMP
)";
to
if (TRUE) {
$sql = "CREATE TABLE $tblname (
id INT(4) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
$name VARCHAR(15) NOT NULL,
$prj VARCHAR(15) NOT NULL,
$userColumn
reg_date TIMESTAMP
)";
Finally the code is below
<?php
$name = test_input($_POST["name"]);
$prj = test_input($_POST["project"]);
$recipe1 = test_input($_POST["recipe1"]);
$recipe2 = test_input($_POST["recipe2"]);
$recipe3 = test_input($_POST["recipe3"]);
$recipe4 = test_input($_POST["recipe4"]);
$tblname = test_input($_POST["prjtitle"]);
$userColumn = ($recipe1 == "" ? "" : $recipe1." VARCHAR(10) NOT NULL,");
$userColumn += ($recipe2 == "" ? "" : $recipe2." VARCHAR(10) NULL,");
$userColumn += ($recipe3 == "" ? "" : $recipe3." VARCHAR(10) NULL,");
$userColumn += ($recipe4 == "" ? "" : $recipe4." VARCHAR(10) NULL,");
$tableExists = mysqli_query($conn, "DESCRIBE $tblname");
if (TRUE) {
$sql = "CREATE TABLE $tblname (
id INT(4) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
$name VARCHAR(15) NOT NULL,
$prj VARCHAR(15) NOT NULL,
$userColumn
reg_date TIMESTAMP
)";
if (mysqli_query($conn, $sql)) {
echo "Table " .$tblname. " created successfully";
} else {
echo "Error creating table: " . mysqli_error($conn);
}
}
mysqli_close($conn);
?>
See 'Conditional Operator' section in http://www.tutorialspoint.com/php/php_operator_types.htm for more information about ?: operator.

Answer 2

The code below works just fine. :
<?php
$name = test_input($_POST["name"]);
$prj = test_input($_POST["project"]);
$recipe1 = test_input($_POST["recipe1"]);
$recipe2 = test_input($_POST["recipe2"]);
$recipe3 = test_input($_POST["recipe3"]);
$recipe4 = test_input($_POST["recipe4"]);
$tblname = test_input($_POST["prjtitle"]);
$recipe2 = (empty($_POST["recipe2"])) ? "recipe2" :
test_input($_POST["recipe2"]);
$recipe3 = (empty($_POST["recipe3"])) ? "recipe3" :
test_input($_POST["recipe3"]);
$recipe4 = (empty($_POST["recipe4"])) ? "recipe4" :
test_input($_POST["recipe4"]);
$tableExists = mysqli_query($conn, "DESCRIBE $tblname");
if (TRUE) {
$sql = "CREATE TABLE $tblname (
id INT(4) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
$name VARCHAR(15) NOT NULL,
$prj VARCHAR(15) NOT NULL,
$recipe1 VARCHAR(15) NOT NULL,
$recipe2 VARCHAR(15) NOT NULL,
$recipe3 VARCHAR(15) NOT NULL,
$recipe4 VARCHAR(15) NOT NULL,
reg_date TIMESTAMP
)";
if (mysqli_query($conn, $sql)) {
echo "Table " .$tblname. " created successfully";
} else {
echo "Error creating table: " . mysqli_error($conn);
}
}
mysqli_close($conn);
?>