Initial import.

1 files changed, 146 insertions, 0 deletions

diff --git a/DbDiff.php b/DbDiff.php
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+<?php
+
+/**
+ * Compare the schemas of between databases.
+ *
+ * For two database schemas to be considered the same, they must have the same
+ * tables, where each table has the same fields, and each field has the same
+ * parameters.
+ *
+ * Field parameters that are compared are those that are given by the MySQL
+ * 'SHOW COLUMNS' command. These are: the field's name, it's type, whether the
+ * field can store null values, whether the column is indexed, the default
+ * values and whether the field was created with the 'auto_increment' keyword.
+ */
+class DbDiff {
+
+	/**
+	 * Export the schema of the database into an array.
+	 *
+	 * @param string $config Config details for the database connection.
+	 * @param string $name Name or description of the database.
+	 * @return mixed|string An array structure of the exported schema, or an error string.
+	 */
+	function export($config, $name) {
+
+		$db = @mysql_connect($config['host'], $config['user'],
+			$config['password']);
+
+		if (!$db) {
+			return null;
+		}
+
+		if (!mysql_select_db($config['name'], $db)) {
+			return null;
+		}
+
+		$result = mysql_query("SHOW TABLES");
+		while ($row = mysql_fetch_row($result)) {
+			$tables[$row[0]] = array();
+		}
+
+		foreach ($tables as $table_name => $fields) {
+
+			$result = mysql_query("SHOW COLUMNS FROM " . $table_name, $db);
+			while ($row = mysql_fetch_assoc($result)) {
+				$tables[$table_name][$row['Field']] = $row;
+			}
+		}
+
+		mysql_close();
+
+		$data = array(
+			'name' => $name,
+			'time' => time(),
+			'tables' => $tables
+		);
+
+		return $data;
+	}
+
+	/**
+	 * Compare two schemas (as generated by the 'export' method.)
+	 *
+	 * @param string $schema1 The first database schema.
+	 * @param string $schema2 The second database schema.
+	 * @return array The results of the comparison.
+	 */
+	function compare($schema1, $schema2) {
+
+		$tables1 = array_keys($schema1['tables']);
+		$tables2 = array_keys($schema2['tables']);
+
+		$tables = array_unique(array_merge($tables1, $tables2));
+
+		$results = array();
+
+		foreach ($tables as $table_name) {
+
+			// Check tables exist in both databases
+
+			if (!isset($schema1['tables'][$table_name])) {
+
+				$results[$table_name][] = '<em>' . $schema1['name']
+					. '</em> is missing table: <code>' . $table_name
+					. '</code>.';
+
+				continue;
+			}
+
+			if (!isset($schema2['tables'][$table_name])) {
+
+				$results[$table_name][] = '<em>' . $schema2['name']
+					. '</em> is missing table: <code>' . $table_name
+					. '</code>.';
+
+				continue;
+			}
+
+			// Check fields exist in both tables
+
+			$fields = array_merge($schema1['tables'][$table_name],
+				$schema2['tables'][$table_name]);
+
+			foreach ($fields as $field_name => $field) {
+
+				if (!isset($schema1['tables'][$table_name][$field_name])) {
+
+					$results[$table_name][] = '<em>' . $schema1['name']
+						. '</em> is missing field: <code>' . $field_name
+						. '</code>';
+
+					continue;
+				}
+
+				if (!isset($schema2['tables'][$table_name][$field_name])) {
+
+					$results[$table_name][] = '<em>' . $schema2['name']
+						. '</em> is missing field: <code>' . $field_name
+						. '</code>';
+
+					continue;
+				}
+
+				// Check that the specific parameters of the fields match
+
+				$s1_params = $schema1['tables'][$table_name][$field_name];
+				$s2_params = $schema2['tables'][$table_name][$field_name];
+
+				foreach ($s1_params as $name => $details) {
+					if ($s1_params[$name] != $s2_params[$name]) {
+						$results[$table_name][] = 'Field <code>' . $field_name
+							. '</code> differs between databases for parameter \''
+							. $name . '\'. <em>' . $schema1['name']
+							. '</em> has \'' . $s1_params[$name]
+							. '\' and <em>' . $schema2['name']
+							. '</em> has \'' . $s2_params[$name] . '\'.';
+					}
+				}
+			}
+		}
+
+		return $results;
+	}
+}
+
+?>