<?php
/**
* @package DATA_MySQL5
*/
/**
* This class provides information about the current schema in
* a MySQL5 database.
*
* Field types returned are those provided by MySQL:
* int,
* varchar,
* text,
* ...etc
*/
class DATA_MySQL5_Schema {
/**
* Cached results of primary keys information.
* @var array
*/
static protected $primaryKeys;
/**
* Cached results of fields information.
* @var array
*/
static protected $fields;
/**
* Cached results of fields with unique indexes information.
* @var array
*/
static protected $uniqueFields;
/**
* Cached results of field definition information.
* @var array
*/
static protected $fieldDefs;
/**
* SQL Type Factories instanciated.
* @var array
*/
static protected $sqlTypeFactories;
/**
* Cached results of auto-increment fields information.
* @var array
*/
static protected $autoIncrementFields;
/**
* Returns the primary key of the indicated table.
* @param string $table The table we would like to know its primary key.
* @return array An array of the columns that compose the primary key.
*/
static public function getPrimaryKey($table) {
if (isset(self::$primaryKeys[$table])) return self::$primaryKeys[$table];
$query = DATA_MySQL5_Access::query("
SELECT column_name
FROM information_schema.columns
WHERE table_schema = DATABASE()
AND table_name = '" . DATA_MySQL5_Access::escape($table) . "'
AND column_key = 'PRI'
");
$keys = array();
while (list($columnName) = DATA_MySQL5_Access::fetchRow($query)) {
$keys[] = $columnName;
}
self::$primaryKeys[$table] = $keys;
return $keys;
}
/**
* Indicates if the specified field is part of the primary key.
* @param string $table The table name.
* @param string $field The field.
* @return bool True if part of the primary key.
*/
public function isPrimaryKey($table, $field) {
return in_array($field, self::getPrimaryKey($table));
}
/**
* Returns the fields of the indicated table.
* @param string $table The table we would like to know its fields.
* @return array An array with the name of the fields.
*/
static public function getFields($table) {
if (isset(self::$fields[$table])) return self::$fields[$table];
$query = DATA_MySQL5_Access::query("
SELECT column_name
FROM information_schema.columns
WHERE table_schema = DATABASE()
AND table_name = '" . DATA_MySQL5_Access::escape($table) . "'
");
$fields = array();
while (list($columnName) = DATA_MySQL5_Access::fetchRow($query)) {
$fields[] = $columnName;
}
self::$fields[$table] = $fields;
return $fields;
}
/**
* Returns the unique indexed fields of the indicated table.
* @param string $table The table we would like to know its unique indexed fields.
* @return array An array with the name of the unique indexed fields.
*/
static public function getUniqueFields($table) {
if (isset(self::$uniqueFields[$table])) return self::$uniqueFields[$table];
$query = DATA_MySQL5_Access::query("
SELECT column_name
FROM information_schema.columns
WHERE table_schema = DATABASE()
AND table_name = '" . DATA_MySQL5_Access::escape($table) . "'
AND column_key = 'UNI'
");
$fields = array();
while (list($columnName) = DATA_MySQL5_Access::fetchRow($query)) {
$fields[] = $columnName;
}
self::$uniqueFields[$table] = $fields;
return $fields;
}
/**
* Returns the type of a field.
* @param string $table The table name.
* @param string $field The field.
* @return string A string representation of the field type.
*/
static public function getFieldType($table, $field) {
$fieldDefinition = self::getFieldDefinition($table, $field);
return $fieldDefinition['data_type'];
}
/**
* Returns the size of a character field.
* @param string $table The table name.
* @param string $field The field.
* @return int The size of the character field.
*/
static public function getCharFieldSize($table, $field) {
$fieldDefinition = self::getFieldDefinition($table, $field);
return (int)$fieldDefinition['character_maximum_length'];
}
/**
* Returns the precision of a numeric field.
* @param string $table The table name.
* @param string $field The field.
* @return int The precision of the numeric field.
*/
static public function getNumericFieldPrecision($table, $field) {
$fieldDefinition = self::getFieldDefinition($table, $field);
return (int)$fieldDefinition['numeric_precision'];
}
/**
* Returns the scale of a numeric field.
* @param string $table The table name.
* @param string $field The field.
* @return int The scale of the numeric field.
*/
static public function getNumericFieldScale($table, $field) {
$fieldDefinition = self::getFieldDefinition($table, $field);
return (int)$fieldDefinition['numeric_scale'];
}
/**
* Indicates if a field is an auto-incremented index.
*
* @param string $table The table name.
* @param string $field The field.
* @return boolean True if the field is an auto-incremented index.
*/
static public function isAutoIncrement($table, $field) {
$fieldDefinition = self::getFieldDefinition($table, $field);
return $fieldDefinition['extra'] == 'auto_increment';
}
/**
* Indicates if a field is nullable.
*
* @param string $table The table name.
* @param string $field The field.
* @return boolean True if the field is nullable.
*/
static public function isNullable($table, $field) {
if (self::isAutoIncrement($table, $field)) return true;
$fieldDefinition = self::getFieldDefinition($table, $field);
return $fieldDefinition['is_nullable'] == 'YES';
}
/**
* Returns internal data regarding the definition of a field.
* @param string $table The table name.
* @param string $field The field.
* @return array Values from the columns definition table.
*/
static protected function getFieldDefinition($table, $field) {
if (isset(self::$fieldDefs[$table][$field])) return self::$fieldDefs[$table][$field];
$query = DATA_MySQL5_Access::query("
SELECT is_nullable, data_type, character_maximum_length, numeric_precision, numeric_scale, extra
FROM information_schema.columns
WHERE table_schema = DATABASE()
AND table_name = '" . DATA_MySQL5_Access::escape($table) . "'
AND column_name = '" . DATA_MySQL5_Access::escape($field) . "'
");
self::$fieldDefs[$table][$field] = DATA_MySQL5_Access::fetchAssoc($query);
return self::$fieldDefs[$table][$field];
}
/**
* Returns the auto-incremented field of a table.
*
* @param string $table The table name.
* @return string The auto-incremented field.
*/
static public function getAutoIncrementField($table) {
if (isset(self::$autoIncrementFields[$table])) return self::$autoIncrementFields[$table];
$query = DATA_MySQL5_Access::query("
SELECT column_name
FROM information_schema.columns
WHERE table_schema = DATABASE()
AND table_name = '" . DATA_MySQL5_Access::escape($table) . "'
AND extra = 'auto_increment'
");
list($field) = DATA_MySQL5_Access::fetchRow($query);
self::$autoIncrementFields[$table] = $field;
return $field;
}
/**
* Returns an internal hash identifying the sql data type of the field.
* @param string $table The table name.
* @param string $field The field.
* @return string Internal hash.
*/
static protected function getFieldTypeHash($table, $field) {
$nullable = self::isNullable($table, $field) ? 'null,' : '';
$fieldType = self::getFieldType($table, $field);
switch ($fieldType) {
case 'char':
case 'varchar':
return $nullable . $fieldType . ',' . self::getCharFieldSize($table, $field);
case 'decimal':
return $nullable . $fieldType . ',' . self::getNumericFieldPrecision($table, $field)
. ',' . self::getNumericFieldScale($table, $field);
default:
return $nullable . $fieldType;
}
}
/**
* Returns the factory used to create sql data types for the specified field.
*
* @param string $table The table name.
* @param string $field The field.
* @return DATA_SQLTypeFactory SQL data type factory.
*/
static public function getSQLTypeFactory($table, $field) {
$fieldHash = self::getFieldTypeHash($table, $field);
$nullable = self::isNullable($table, $field);
if (isset(self::$sqlTypeFactories[$fieldHash])) return self::$sqlTypeFactories[$fieldHash];
switch (self::getFieldType($table, $field)) {
case 'char':
$factory = new DATA_SQLCharFactory($nullable, self::getCharFieldSize($table, $field));
break;
case 'varchar':
$factory = new DATA_SQLVarcharFactory($nullable, self::getCharFieldSize($table, $field));
break;
case 'int':
$factory = new DATA_SQLIntFactory($nullable);
break;
case 'smallint':
$factory = new DATA_SQLSmallIntFactory($nullable);
break;
case 'decimal':
$factory = new DATA_SQLDecimalFactory($nullable, self::getNumericFieldPrecision($table, $field),
self::getNumericFieldScale($table, $field));
break;
case 'date':
$factory = new DATA_MySQL5_SQLDateFactory($nullable);
break;
case 'time':
$factory = new DATA_MySQL5_SQLTimeFactory($nullable);
break;
case 'datetime':
$factory = new DATA_MySQL5_SQLDatetimeFactory($nullable);
break;
default:
throw new DATA_NotImplemented("Factory for field of type '" . self::getFieldType($table, $field) . "'");
break;
}
self::$sqlTypeFactories[$fieldHash] = $factory;
return $factory;
}
}
?>
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