building db query with a for loop - php

Question

I've made a function to query the database. This function takes an array, the id of the user I want to update
and a query operation.
if the query operation is UPDATE
if you look at the code below, would this be a good coding practice or is this bad code?
public function query($column, $search_value, $query_operation = "SELECT"){
if(strtoupper($query_operation == "UPDATE")){
$query = "UPDATE users SET ";
if(is_array($column)){
$counter = 1;
foreach($column as $key => $value){
if($counter < count($column)){
$query .= $key . ' = ?, ';
}else{
$query .= $key . ' = ? ';
}
$counter++;
}
$query .= "WHERE id = ?";
$stmt = $this->database->prepare($query);
$counter = 1;
foreach($column as $key => &$value){
$stmt->bindParam($counter, $value);
$counter++;
}
$stmt->bindParam($counter, $search_value);
if($stmt->execute()){
$stmt = $this->database->prepare("SELECT* FROM
users WHERE id = ?");
$stmt->bindParam(1, $search_value, PDO::PARAM_INT);
$stmt->execute();
return $this->build_array($stmt);
}
}
}
}
would love to hear some feedback.

Answer 1

I would NOT mix SELECT and UPDATE in the same function.
The following update function uses arrays for column names and values $columnNames & $values using unnamed parameters.
function update($tableName,$columnNames,$values,$fieldName,$fieldValue){
$sql = "UPDATE `$tableName` SET ";
foreach($columnNames as $field){
$sql .= $field ." = ?,";
}
$sql = substr($sql, 0, -1);//remove trailing ,
$sql .= " WHERE `$fieldName` = ?";
return $sql;
}
As table and column names cannot be passed as parameters in PDO I have demonstrated whitelistng of table names.
$tables = array("client", "Table1", "Table2");// Array of allowed table names.
Also array_push()to add value for last parameter (WHERE) into $values array
Use
if (in_array($tableName, $tables)) {
$sql = update($tableName,$columnNames,$values,$fieldName,$fieldValue);
array_push($values,$fieldValue);
$STH = $DBH->prepare($sql);
$STH->execute($values);
}
You can use similar technique for SELECT