FM / db

/var/www/vhosts/nabawater/vendor/yiisoft/yii2/db/

/var/www/vhosts/nabawater/vendor/yiisoft/yii2/db

Name	Size	Mode	Actions
conditions/	-	0755	rm
cubrid/	-	0755	rm
mssql/	-	0755	rm
mysql/	-	0755	rm
oci/	-	0755	rm
pgsql/	-	0755	rm
sqlite/	-	0755	rm
ActiveQuery.php	31506	0644	edit dl rm
ActiveQueryInterface.php	4542	0644	edit dl rm
ActiveQueryTrait.php	6315	0644	edit dl rm
ActiveRecord.php	29789	0644	edit dl rm
ActiveRecordInterface.php	21207	0644	edit dl rm
ActiveRelationTrait.php	23292	0644	edit dl rm
AfterSaveEvent.php	553	0644	edit dl rm
ArrayExpression.php	5400	0644	edit dl rm
BaseActiveRecord.php	69538	0644	edit dl rm
BatchQueryResult.php	4905	0644	edit dl rm
CheckConstraint.php	458	0644	edit dl rm
ColumnSchema.php	5356	0644	edit dl rm
ColumnSchemaBuilder.php	13287	0644	edit dl rm
Command.php	52026	0644	edit dl rm
Connection.php	45376	0644	edit dl rm
Constraint.php	566	0644	edit dl rm
ConstraintFinderInterface.php	6454	0644	edit dl rm
ConstraintFinderTrait.php	11204	0644	edit dl rm
DataReader.php	8518	0644	edit dl rm
DefaultValueConstraint.php	472	0644	edit dl rm
Exception.php	1457	0644	edit dl rm
Expression.php	1909	0644	edit dl rm
ExpressionBuilder.php	741	0644	edit dl rm
ExpressionBuilderInterface.php	860	0644	edit dl rm
ExpressionBuilderTrait.php	707	0644	edit dl rm
ExpressionInterface.php	615	0644	edit dl rm
ForeignKeyConstraint.php	937	0644	edit dl rm
IndexConstraint.php	553	0644	edit dl rm
IntegrityException.php	546	0644	edit dl rm
JsonExpression.php	2684	0644	edit dl rm
Migration.php	26933	0644	edit dl rm
MigrationInterface.php	1226	0644	edit dl rm
PdoValue.php	1370	0644	edit dl rm
PdoValueBuilder.php	692	0644	edit dl rm
Query.php	49520	0644	edit dl rm
QueryBuilder.php	74240	0644	edit dl rm
QueryExpressionBuilder.php	1044	0644	edit dl rm
QueryInterface.php	12820	0644	edit dl rm
QueryTrait.php	15155	0644	edit dl rm
Schema.php	31377	0644	edit dl rm
SchemaBuilderTrait.php	11495	0644	edit dl rm
SqlToken.php	9676	0644	edit dl rm
SqlTokenizer.php	14208	0644	edit dl rm
StaleObjectException.php	447	0644	edit dl rm
TableSchema.php	3129	0644	edit dl rm
Transaction.php	9365	0644	edit dl rm
ViewFinderTrait.php	1614	0644	edit dl rm

Edit: /var/www/vhosts/nabawater/vendor/yiisoft/yii2/db/Schema.php (31377B)

<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\db;

use Yii;
use yii\base\BaseObject;
use yii\base\InvalidCallException;
use yii\base\InvalidConfigException;
use yii\base\NotSupportedException;
use yii\caching\Cache;
use yii\caching\CacheInterface;
use yii\caching\TagDependency;
use yii\helpers\StringHelper;

/**
 * Schema is the base class for concrete DBMS-specific schema classes.
 *
 * Schema represents the database schema information that is DBMS specific.
 *
 * @property string $lastInsertID The row ID of the last row inserted, or the last value retrieved from the
 * sequence object. This property is read-only.
 * @property QueryBuilder $queryBuilder The query builder for this connection. This property is read-only.
 * @property string[] $schemaNames All schema names in the database, except system schemas. This property is
 * read-only.
 * @property string $serverVersion Server version as a string. This property is read-only.
 * @property string[] $tableNames All table names in the database. This property is read-only.
 * @property TableSchema[] $tableSchemas The metadata for all tables in the database. Each array element is an
 * instance of [[TableSchema]] or its child class. This property is read-only.
 * @property string $transactionIsolationLevel The transaction isolation level to use for this transaction.
 * This can be one of [[Transaction::READ_UNCOMMITTED]], [[Transaction::READ_COMMITTED]],
 * [[Transaction::REPEATABLE_READ]] and [[Transaction::SERIALIZABLE]] but also a string containing DBMS specific
 * syntax to be used after `SET TRANSACTION ISOLATION LEVEL`. This property is write-only.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @author Sergey Makinen <sergey@makinen.ru>
 * @since 2.0
 */
abstract class Schema extends BaseObject
{
    // The following are the supported abstract column data types.
    const TYPE_PK = 'pk';
    const TYPE_UPK = 'upk';
    const TYPE_BIGPK = 'bigpk';
    const TYPE_UBIGPK = 'ubigpk';
    const TYPE_CHAR = 'char';
    const TYPE_STRING = 'string';
    const TYPE_TEXT = 'text';
    const TYPE_TINYINT = 'tinyint';
    const TYPE_SMALLINT = 'smallint';
    const TYPE_INTEGER = 'integer';
    const TYPE_BIGINT = 'bigint';
    const TYPE_FLOAT = 'float';
    const TYPE_DOUBLE = 'double';
    const TYPE_DECIMAL = 'decimal';
    const TYPE_DATETIME = 'datetime';
    const TYPE_TIMESTAMP = 'timestamp';
    const TYPE_TIME = 'time';
    const TYPE_DATE = 'date';
    const TYPE_BINARY = 'binary';
    const TYPE_BOOLEAN = 'boolean';
    const TYPE_MONEY = 'money';
    const TYPE_JSON = 'json';
    /**
     * Schema cache version, to detect incompatibilities in cached values when the
     * data format of the cache changes.
     */
    const SCHEMA_CACHE_VERSION = 1;

/**
     * @var Connection the database connection
     */
    public $db;
    /**
     * @var string the default schema name used for the current session.
     */
    public $defaultSchema;
    /**
     * @var array map of DB errors and corresponding exceptions
     * If left part is found in DB error message exception class from the right part is used.
     */
    public $exceptionMap = [
        'SQLSTATE[23' => 'yii\db\IntegrityException',
    ];
    /**
     * @var string|array column schema class or class config
     * @since 2.0.11
     */
    public $columnSchemaClass = 'yii\db\ColumnSchema';

/**
     * @var string|string[] character used to quote schema, table, etc. names.
     * An array of 2 characters can be used in case starting and ending characters are different.
     * @since 2.0.14
     */
    protected $tableQuoteCharacter = "'";
    /**
     * @var string|string[] character used to quote column names.
     * An array of 2 characters can be used in case starting and ending characters are different.
     * @since 2.0.14
     */
    protected $columnQuoteCharacter = '"';

/**
     * @var array list of ALL schema names in the database, except system schemas
     */
    private $_schemaNames;
    /**
     * @var array list of ALL table names in the database
     */
    private $_tableNames = [];
    /**
     * @var array list of loaded table metadata (table name => metadata type => metadata).
     */
    private $_tableMetadata = [];
    /**
     * @var QueryBuilder the query builder for this database
     */
    private $_builder;
    /**
     * @var string server version as a string.
     */
    private $_serverVersion;

/**
     * Resolves the table name and schema name (if any).
     * @param string $name the table name
     * @return TableSchema [[TableSchema]] with resolved table, schema, etc. names.
     * @throws NotSupportedException if this method is not supported by the DBMS.
     * @since 2.0.13
     */
    protected function resolveTableName($name)
    {
        throw new NotSupportedException(get_class($this) . ' does not support resolving table names.');
    }

/**
     * Returns all schema names in the database, including the default one but not system schemas.
     * This method should be overridden by child classes in order to support this feature
     * because the default implementation simply throws an exception.
     * @return array all schema names in the database, except system schemas.
     * @throws NotSupportedException if this method is not supported by the DBMS.
     * @since 2.0.4
     */
    protected function findSchemaNames()
    {
        throw new NotSupportedException(get_class($this) . ' does not support fetching all schema names.');
    }

/**
     * Returns all table names in the database.
     * This method should be overridden by child classes in order to support this feature
     * because the default implementation simply throws an exception.
     * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
     * @return array all table names in the database. The names have NO schema name prefix.
     * @throws NotSupportedException if this method is not supported by the DBMS.
     */
    protected function findTableNames($schema = '')
    {
        throw new NotSupportedException(get_class($this) . ' does not support fetching all table names.');
    }

/**
     * Loads the metadata for the specified table.
     * @param string $name table name
     * @return TableSchema|null DBMS-dependent table metadata, `null` if the table does not exist.
     */
    abstract protected function loadTableSchema($name);

/**
     * Creates a column schema for the database.
     * This method may be overridden by child classes to create a DBMS-specific column schema.
     * @return ColumnSchema column schema instance.
     * @throws InvalidConfigException if a column schema class cannot be created.
     */
    protected function createColumnSchema()
    {
        return Yii::createObject($this->columnSchemaClass);
    }

/**
     * Obtains the metadata for the named table.
     * @param string $name table name. The table name may contain schema name if any. Do not quote the table name.
     * @param bool $refresh whether to reload the table schema even if it is found in the cache.
     * @return TableSchema|null table metadata. `null` if the named table does not exist.
     */
    public function getTableSchema($name, $refresh = false)
    {
        return $this->getTableMetadata($name, 'schema', $refresh);
    }

/**
     * Returns the metadata for all tables in the database.
     * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema name.
     * @param bool $refresh whether to fetch the latest available table schemas. If this is `false`,
     * cached data may be returned if available.
     * @return TableSchema[] the metadata for all tables in the database.
     * Each array element is an instance of [[TableSchema]] or its child class.
     */
    public function getTableSchemas($schema = '', $refresh = false)
    {
        return $this->getSchemaMetadata($schema, 'schema', $refresh);
    }

/**
     * Returns all schema names in the database, except system schemas.
     * @param bool $refresh whether to fetch the latest available schema names. If this is false,
     * schema names fetched previously (if available) will be returned.
     * @return string[] all schema names in the database, except system schemas.
     * @since 2.0.4
     */
    public function getSchemaNames($refresh = false)
    {
        if ($this->_schemaNames === null || $refresh) {
            $this->_schemaNames = $this->findSchemaNames();
        }

return $this->_schemaNames;
    }

/**
     * Returns all table names in the database.
     * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema name.
     * If not empty, the returned table names will be prefixed with the schema name.
     * @param bool $refresh whether to fetch the latest available table names. If this is false,
     * table names fetched previously (if available) will be returned.
     * @return string[] all table names in the database.
     */
    public function getTableNames($schema = '', $refresh = false)
    {
        if (!isset($this->_tableNames[$schema]) || $refresh) {
            $this->_tableNames[$schema] = $this->findTableNames($schema);
        }

return $this->_tableNames[$schema];
    }

/**
     * @return QueryBuilder the query builder for this connection.
     */
    public function getQueryBuilder()
    {
        if ($this->_builder === null) {
            $this->_builder = $this->createQueryBuilder();
        }

return $this->_builder;
    }

/**
     * Determines the PDO type for the given PHP data value.
     * @param mixed $data the data whose PDO type is to be determined
     * @return int the PDO type
     * @see http://www.php.net/manual/en/pdo.constants.php
     */
    public function getPdoType($data)
    {
        static $typeMap = [
            // php type => PDO type
            'boolean' => \PDO::PARAM_BOOL,
            'integer' => \PDO::PARAM_INT,
            'string' => \PDO::PARAM_STR,
            'resource' => \PDO::PARAM_LOB,
            'NULL' => \PDO::PARAM_NULL,
        ];
        $type = gettype($data);

return isset($typeMap[$type]) ? $typeMap[$type] : \PDO::PARAM_STR;
    }

/**
     * Refreshes the schema.
     * This method cleans up all cached table schemas so that they can be re-created later
     * to reflect the database schema change.
     */
    public function refresh()
    {
        /* @var $cache CacheInterface */
        $cache = is_string($this->db->schemaCache) ? Yii::$app->get($this->db->schemaCache, false) : $this->db->schemaCache;
        if ($this->db->enableSchemaCache && $cache instanceof CacheInterface) {
            TagDependency::invalidate($cache, $this->getCacheTag());
        }
        $this->_tableNames = [];
        $this->_tableMetadata = [];
    }

/**
     * Refreshes the particular table schema.
     * This method cleans up cached table schema so that it can be re-created later
     * to reflect the database schema change.
     * @param string $name table name.
     * @since 2.0.6
     */
    public function refreshTableSchema($name)
    {
        $rawName = $this->getRawTableName($name);
        unset($this->_tableMetadata[$rawName]);
        $this->_tableNames = [];
        /* @var $cache CacheInterface */
        $cache = is_string($this->db->schemaCache) ? Yii::$app->get($this->db->schemaCache, false) : $this->db->schemaCache;
        if ($this->db->enableSchemaCache && $cache instanceof CacheInterface) {
            $cache->delete($this->getCacheKey($rawName));
        }
    }

/**
     * Creates a query builder for the database.
     * This method may be overridden by child classes to create a DBMS-specific query builder.
     * @return QueryBuilder query builder instance
     */
    public function createQueryBuilder()
    {
        return new QueryBuilder($this->db);
    }

/**
     * Create a column schema builder instance giving the type and value precision.
     *
     * This method may be overridden by child classes to create a DBMS-specific column schema builder.
     *
     * @param string $type type of the column. See [[ColumnSchemaBuilder::$type]].
     * @param int|string|array $length length or precision of the column. See [[ColumnSchemaBuilder::$length]].
     * @return ColumnSchemaBuilder column schema builder instance
     * @since 2.0.6
     */
    public function createColumnSchemaBuilder($type, $length = null)
    {
        return new ColumnSchemaBuilder($type, $length);
    }

/**
     * Returns all unique indexes for the given table.
     *
     * Each array element is of the following structure:
     *
     * ```php
     * [
     *  'IndexName1' => ['col1' [, ...]],
     *  'IndexName2' => ['col2' [, ...]],
     * ]
     * ```
     *
     * This method should be overridden by child classes in order to support this feature
     * because the default implementation simply throws an exception
     * @param TableSchema $table the table metadata
     * @return array all unique indexes for the given table.
     * @throws NotSupportedException if this method is called
     */
    public function findUniqueIndexes($table)
    {
        throw new NotSupportedException(get_class($this) . ' does not support getting unique indexes information.');
    }

/**
     * Returns the ID of the last inserted row or sequence value.
     * @param string $sequenceName name of the sequence object (required by some DBMS)
     * @return string the row ID of the last row inserted, or the last value retrieved from the sequence object
     * @throws InvalidCallException if the DB connection is not active
     * @see http://www.php.net/manual/en/function.PDO-lastInsertId.php
     */
    public function getLastInsertID($sequenceName = '')
    {
        if ($this->db->isActive) {
            return $this->db->pdo->lastInsertId($sequenceName === '' ? null : $this->quoteTableName($sequenceName));
        }

throw new InvalidCallException('DB Connection is not active.');
    }

/**
     * @return bool whether this DBMS supports [savepoint](http://en.wikipedia.org/wiki/Savepoint).
     */
    public function supportsSavepoint()
    {
        return $this->db->enableSavepoint;
    }

/**
     * Creates a new savepoint.
     * @param string $name the savepoint name
     */
    public function createSavepoint($name)
    {
        $this->db->createCommand("SAVEPOINT $name")->execute();
    }

/**
     * Releases an existing savepoint.
     * @param string $name the savepoint name
     */
    public function releaseSavepoint($name)
    {
        $this->db->createCommand("RELEASE SAVEPOINT $name")->execute();
    }

/**
     * Rolls back to a previously created savepoint.
     * @param string $name the savepoint name
     */
    public function rollBackSavepoint($name)
    {
        $this->db->createCommand("ROLLBACK TO SAVEPOINT $name")->execute();
    }

/**
     * Sets the isolation level of the current transaction.
     * @param string $level The transaction isolation level to use for this transaction.
     * This can be one of [[Transaction::READ_UNCOMMITTED]], [[Transaction::READ_COMMITTED]], [[Transaction::REPEATABLE_READ]]
     * and [[Transaction::SERIALIZABLE]] but also a string containing DBMS specific syntax to be used
     * after `SET TRANSACTION ISOLATION LEVEL`.
     * @see http://en.wikipedia.org/wiki/Isolation_%28database_systems%29#Isolation_levels
     */
    public function setTransactionIsolationLevel($level)
    {
        $this->db->createCommand("SET TRANSACTION ISOLATION LEVEL $level")->execute();
    }

/**
     * Executes the INSERT command, returning primary key values.
     * @param string $table the table that new rows will be inserted into.
     * @param array $columns the column data (name => value) to be inserted into the table.
     * @return array|false primary key values or false if the command fails
     * @since 2.0.4
     */
    public function insert($table, $columns)
    {
        $command = $this->db->createCommand()->insert($table, $columns);
        if (!$command->execute()) {
            return false;
        }
        $tableSchema = $this->getTableSchema($table);
        $result = [];
        foreach ($tableSchema->primaryKey as $name) {
            if ($tableSchema->columns[$name]->autoIncrement) {
                $result[$name] = $this->getLastInsertID($tableSchema->sequenceName);
                break;
            }

$result[$name] = isset($columns[$name]) ? $columns[$name] : $tableSchema->columns[$name]->defaultValue;
        }

return $result;
    }

/**
     * Quotes a string value for use in a query.
     * Note that if the parameter is not a string, it will be returned without change.
     * @param string $str string to be quoted
     * @return string the properly quoted string
     * @see http://www.php.net/manual/en/function.PDO-quote.php
     */
    public function quoteValue($str)
    {
        if (!is_string($str)) {
            return $str;
        }

if (($value = $this->db->getSlavePdo()->quote($str)) !== false) {
            return $value;
        }

// the driver doesn't support quote (e.g. oci)
        return "'" . addcslashes(str_replace("'", "''", $str), "\000\n\r\\\032") . "'";
    }

/**
     * Quotes a table name for use in a query.
     * If the table name contains schema prefix, the prefix will also be properly quoted.
     * If the table name is already quoted or contains '(' or '{{',
     * then this method will do nothing.
     * @param string $name table name
     * @return string the properly quoted table name
     * @see quoteSimpleTableName()
     */
    public function quoteTableName($name)
    {
        if (strpos($name, '(') !== false || strpos($name, '{{') !== false) {
            return $name;
        }
        if (strpos($name, '.') === false) {
            return $this->quoteSimpleTableName($name);
        }
        $parts = explode('.', $name);
        foreach ($parts as $i => $part) {
            $parts[$i] = $this->quoteSimpleTableName($part);
        }

return implode('.', $parts);
    }

/**
     * Quotes a column name for use in a query.
     * If the column name contains prefix, the prefix will also be properly quoted.
     * If the column name is already quoted or contains '(', '[[' or '{{',
     * then this method will do nothing.
     * @param string $name column name
     * @return string the properly quoted column name
     * @see quoteSimpleColumnName()
     */
    public function quoteColumnName($name)
    {
        if (strpos($name, '(') !== false || strpos($name, '[[') !== false) {
            return $name;
        }
        if (($pos = strrpos($name, '.')) !== false) {
            $prefix = $this->quoteTableName(substr($name, 0, $pos)) . '.';
            $name = substr($name, $pos + 1);
        } else {
            $prefix = '';
        }
        if (strpos($name, '{{') !== false) {
            return $name;
        }

return $prefix . $this->quoteSimpleColumnName($name);
    }

/**
     * Quotes a simple table name for use in a query.
     * A simple table name should contain the table name only without any schema prefix.
     * If the table name is already quoted, this method will do nothing.
     * @param string $name table name
     * @return string the properly quoted table name
     */
    public function quoteSimpleTableName($name)
    {
        if (is_string($this->tableQuoteCharacter)) {
            $startingCharacter = $endingCharacter = $this->tableQuoteCharacter;
        } else {
            list($startingCharacter, $endingCharacter) = $this->tableQuoteCharacter;
        }
        return strpos($name, $startingCharacter) !== false ? $name : $startingCharacter . $name . $endingCharacter;
    }

/**
     * Quotes a simple column name for use in a query.
     * A simple column name should contain the column name only without any prefix.
     * If the column name is already quoted or is the asterisk character '*', this method will do nothing.
     * @param string $name column name
     * @return string the properly quoted column name
     */
    public function quoteSimpleColumnName($name)
    {
        if (is_string($this->tableQuoteCharacter)) {
            $startingCharacter = $endingCharacter = $this->columnQuoteCharacter;
        } else {
            list($startingCharacter, $endingCharacter) = $this->columnQuoteCharacter;
        }
        return $name === '*' || strpos($name, $startingCharacter) !== false ? $name : $startingCharacter . $name . $endingCharacter;
    }

/**
     * Unquotes a simple table name.
     * A simple table name should contain the table name only without any schema prefix.
     * If the table name is not quoted, this method will do nothing.
     * @param string $name table name.
     * @return string unquoted table name.
     * @since 2.0.14
     */
    public function unquoteSimpleTableName($name)
    {
        if (is_string($this->tableQuoteCharacter)) {
            $startingCharacter = $this->tableQuoteCharacter;
        } else {
            $startingCharacter = $this->tableQuoteCharacter[0];
        }
        return strpos($name, $startingCharacter) === false ? $name : substr($name, 1, -1);
    }

/**
     * Unquotes a simple column name.
     * A simple column name should contain the column name only without any prefix.
     * If the column name is not quoted or is the asterisk character '*', this method will do nothing.
     * @param string $name column name.
     * @return string unquoted column name.
     * @since 2.0.14
     */
    public function unquoteSimpleColumnName($name)
    {
        if (is_string($this->columnQuoteCharacter)) {
            $startingCharacter = $this->columnQuoteCharacter;
        } else {
            $startingCharacter = $this->columnQuoteCharacter[0];
        }
        return strpos($name, $startingCharacter) === false ? $name : substr($name, 1, -1);
    }

/**
     * Returns the actual name of a given table name.
     * This method will strip off curly brackets from the given table name
     * and replace the percentage character '%' with [[Connection::tablePrefix]].
     * @param string $name the table name to be converted
     * @return string the real name of the given table name
     */
    public function getRawTableName($name)
    {
        if (strpos($name, '{{') !== false) {
            $name = preg_replace('/\\{\\{(.*?)\\}\\}/', '\1', $name);

return str_replace('%', $this->db->tablePrefix, $name);
        }

return $name;
    }

/**
     * Extracts the PHP type from abstract DB type.
     * @param ColumnSchema $column the column schema information
     * @return string PHP type name
     */
    protected function getColumnPhpType($column)
    {
        static $typeMap = [
            // abstract type => php type
            self::TYPE_TINYINT => 'integer',
            self::TYPE_SMALLINT => 'integer',
            self::TYPE_INTEGER => 'integer',
            self::TYPE_BIGINT => 'integer',
            self::TYPE_BOOLEAN => 'boolean',
            self::TYPE_FLOAT => 'double',
            self::TYPE_DOUBLE => 'double',
            self::TYPE_BINARY => 'resource',
            self::TYPE_JSON => 'array',
        ];
        if (isset($typeMap[$column->type])) {
            if ($column->type === 'bigint') {
                return PHP_INT_SIZE === 8 && !$column->unsigned ? 'integer' : 'string';
            } elseif ($column->type === 'integer') {
                return PHP_INT_SIZE === 4 && $column->unsigned ? 'string' : 'integer';
            }

return $typeMap[$column->type];
        }

return 'string';
    }

/**
     * Converts a DB exception to a more concrete one if possible.
     *
     * @param \Exception $e
     * @param string $rawSql SQL that produced exception
     * @return Exception
     */
    public function convertException(\Exception $e, $rawSql)
    {
        if ($e instanceof Exception) {
            return $e;
        }

$exceptionClass = '\yii\db\Exception';
        foreach ($this->exceptionMap as $error => $class) {
            if (strpos($e->getMessage(), $error) !== false) {
                $exceptionClass = $class;
            }
        }
        $message = $e->getMessage() . "\nThe SQL being executed was: $rawSql";
        $errorInfo = $e instanceof \PDOException ? $e->errorInfo : null;
        return new $exceptionClass($message, $errorInfo, (int) $e->getCode(), $e);
    }

/**
     * Returns a value indicating whether a SQL statement is for read purpose.
     * @param string $sql the SQL statement
     * @return bool whether a SQL statement is for read purpose.
     */
    public function isReadQuery($sql)
    {
        $pattern = '/^\s*(SELECT|SHOW|DESCRIBE)\b/i';
        return preg_match($pattern, $sql) > 0;
    }

/**
     * Returns a server version as a string comparable by [[\version_compare()]].
     * @return string server version as a string.
     * @since 2.0.14
     */
    public function getServerVersion()
    {
        if ($this->_serverVersion === null) {
            $this->_serverVersion = $this->db->getSlavePdo()->getAttribute(\PDO::ATTR_SERVER_VERSION);
        }
        return $this->_serverVersion;
    }

/**
     * Returns the cache key for the specified table name.
     * @param string $name the table name.
     * @return mixed the cache key.
     */
    protected function getCacheKey($name)
    {
        return [
            __CLASS__,
            $this->db->dsn,
            $this->db->username,
            $this->getRawTableName($name),
        ];
    }

/**
     * Returns the cache tag name.
     * This allows [[refresh()]] to invalidate all cached table schemas.
     * @return string the cache tag name
     */
    protected function getCacheTag()
    {
        return md5(serialize([
            __CLASS__,
            $this->db->dsn,
            $this->db->username,
        ]));
    }

/**
     * Returns the metadata of the given type for the given table.
     * If there's no metadata in the cache, this method will call
     * a `'loadTable' . ucfirst($type)` named method with the table name to obtain the metadata.
     * @param string $name table name. The table name may contain schema name if any. Do not quote the table name.
     * @param string $type metadata type.
     * @param bool $refresh whether to reload the table metadata even if it is found in the cache.
     * @return mixed metadata.
     * @since 2.0.13
     */
    protected function getTableMetadata($name, $type, $refresh)
    {
        $cache = null;
        if ($this->db->enableSchemaCache && !in_array($name, $this->db->schemaCacheExclude, true)) {
            $schemaCache = is_string($this->db->schemaCache) ? Yii::$app->get($this->db->schemaCache, false) : $this->db->schemaCache;
            if ($schemaCache instanceof CacheInterface) {
                $cache = $schemaCache;
            }
        }
        $rawName = $this->getRawTableName($name);
        if (!isset($this->_tableMetadata[$rawName])) {
            $this->loadTableMetadataFromCache($cache, $rawName);
        }
        if ($refresh || !array_key_exists($type, $this->_tableMetadata[$rawName])) {
            $this->_tableMetadata[$rawName][$type] = $this->{'loadTable' . ucfirst($type)}($rawName);
            $this->saveTableMetadataToCache($cache, $rawName);
        }

return $this->_tableMetadata[$rawName][$type];
    }

/**
     * Returns the metadata of the given type for all tables in the given schema.
     * This method will call a `'getTable' . ucfirst($type)` named method with the table name
     * and the refresh flag to obtain the metadata.
     * @param string $schema the schema of the metadata. Defaults to empty string, meaning the current or default schema name.
     * @param string $type metadata type.
     * @param bool $refresh whether to fetch the latest available table metadata. If this is `false`,
     * cached data may be returned if available.
     * @return array array of metadata.
     * @since 2.0.13
     */
    protected function getSchemaMetadata($schema, $type, $refresh)
    {
        $metadata = [];
        $methodName = 'getTable' . ucfirst($type);
        foreach ($this->getTableNames($schema, $refresh) as $name) {
            if ($schema !== '') {
                $name = $schema . '.' . $name;
            }
            $tableMetadata = $this->$methodName($name, $refresh);
            if ($tableMetadata !== null) {
                $metadata[] = $tableMetadata;
            }
        }

return $metadata;
    }

/**
     * Sets the metadata of the given type for the given table.
     * @param string $name table name.
     * @param string $type metadata type.
     * @param mixed $data metadata.
     * @since 2.0.13
     */
    protected function setTableMetadata($name, $type, $data)
    {
        $this->_tableMetadata[$this->getRawTableName($name)][$type] = $data;
    }

/**
     * Changes row's array key case to lower if PDO's one is set to uppercase.
     * @param array $row row's array or an array of row's arrays.
     * @param bool $multiple whether multiple rows or a single row passed.
     * @return array normalized row or rows.
     * @since 2.0.13
     */
    protected function normalizePdoRowKeyCase(array $row, $multiple)
    {
        if ($this->db->getSlavePdo()->getAttribute(\PDO::ATTR_CASE) !== \PDO::CASE_UPPER) {
            return $row;
        }

if ($multiple) {
            return array_map(function (array $row) {
                return array_change_key_case($row, CASE_LOWER);
            }, $row);
        }

return array_change_key_case($row, CASE_LOWER);
    }

/**
     * Tries to load and populate table metadata from cache.
     * @param Cache|null $cache
     * @param string $name
     */
    private function loadTableMetadataFromCache($cache, $name)
    {
        if ($cache === null) {
            $this->_tableMetadata[$name] = [];
            return;
        }

$metadata = $cache->get($this->getCacheKey($name));
        if (!is_array($metadata) || !isset($metadata['cacheVersion']) || $metadata['cacheVersion'] !== static::SCHEMA_CACHE_VERSION) {
            $this->_tableMetadata[$name] = [];
            return;
        }

unset($metadata['cacheVersion']);
        $this->_tableMetadata[$name] = $metadata;
    }

/**
     * Saves table metadata to cache.
     * @param Cache|null $cache
     * @param string $name
     */
    private function saveTableMetadataToCache($cache, $name)
    {
        if ($cache === null) {
            return;
        }

$metadata = $this->_tableMetadata[$name];
        $metadata['cacheVersion'] = static::SCHEMA_CACHE_VERSION;
        $cache->set(
            $this->getCacheKey($name),
            $metadata,
            $this->db->schemaCacheDuration,
            new TagDependency(['tags' => $this->getCacheTag()])
        );
    }
}

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