Add a method to the schema class column_exists, and sqlite_column_exists, and table_info.

resources/classes/schema.php

@@ -118,6 +118,80 @@ include "root.php";
 						$this->db->commit();
 				}
 			}
+
+		//check if a column exists in sqlite
+			private function sqlite_column_exists($table_info, $column_name) {
+				foreach ($table_info as $key => &$row) {
+					if ($row['name'] == $column_name) {
+						return true;
+					}
+				}
+				return $false;
+			}
+
+		//check if a column exists
+			public function column_exists ($db_type, $db_name, $table_name, $column_name) {
+				global $display_type;
+
+				if ($db_type == "sqlite") {
+					$table_info = $this->table_info($db_name, $db_type, $table_name);
+					if ($this->sqlite_column_exists($table_info, $column_name)) {
+						return true;
+					}
+					else {
+						return false;
+					}
+				}
+				if ($db_type == "pgsql") {
+					$sql = "SELECT attname FROM pg_attribute WHERE attrelid = (SELECT oid FROM pg_class WHERE relname = '$table_name') AND attname = '$column_name'; ";
+				}
+				if ($db_type == "mysql") {
+					//$sql .= "SELECT * FROM information_schema.COLUMNS where TABLE_SCHEMA = '$db_name' and TABLE_NAME = '$table_name' and COLUMN_NAME = '$column_name' ";
+					$sql = "show columns from $table_name where field = '$column_name' ";
+				}
+				if ($sql) {
+					$prep_statement = $this->db->prepare(check_sql($sql));
+					$prep_statement->execute();
+					$result = $prep_statement->fetchAll(PDO::FETCH_NAMED);
+					if (!$result) {
+						return false;
+					}
+					if (count($result) > 0) {
+						return true;
+					}
+					else {
+						return false;
+					}
+					unset ($prep_statement);
+				}
+			}
+
+		//get the table information
+			public function table_info($db_name, $db_type, $table_name) {
+				if (strlen($table_name) == 0) { return false; }
+				if ($db_type == "sqlite") {
+					$sql = "PRAGMA table_info(".$table_name.");";
+				}
+				if ($db_type == "pgsql") {
+					$sql = "SELECT ordinal_position, ";
+					$sql .= "column_name, ";
+					$sql .= "data_type, ";
+					$sql .= "column_default, ";
+					$sql .= "is_nullable, ";
+					$sql .= "character_maximum_length, ";
+					$sql .= "numeric_precision ";
+					$sql .= "FROM information_schema.columns ";
+					$sql .= "WHERE table_name = '".$table_name."' ";
+					$sql .= "and table_catalog = '".$db_name."' ";
+					$sql .= "ORDER BY ordinal_position; ";
+				}
+				if ($db_type == "mysql") {
+					$sql = "describe ".$table_name.";";
+				}
+				$prep_statement = $this->db->prepare($sql);
+				$prep_statement->execute();
+				return $prep_statement->fetchAll(PDO::FETCH_ASSOC);
+			}
 	}
 
 //example use