SQLServerPlatform.php

<?php

/*
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the LGPL. For more information, see
 * <http://www.doctrine-project.org>.
 */

namespace Doctrine\DBAL\Platforms;

use Doctrine\DBAL\Schema\TableDiff;
use Doctrine\DBAL\DBALException;
use Doctrine\DBAL\Schema\Index,
    Doctrine\DBAL\Schema\Table;

/**
 * The SQLServerPlatform provides the behavior, features and SQL dialect of the
 * Microsoft SQL Server database platform.
 *
 * @since 2.0
 * @author Roman Borschel <roman@code-factory.org>
 * @author Jonathan H. Wage <jonwage@gmail.com>
 * @author Benjamin Eberlei <kontakt@beberlei.de>
 */
class SQLServerPlatform extends AbstractPlatform
{
    /**
     * {@inheritDoc}
     */
    public function getDateDiffExpression($date1, $date2)
    {
        return 'DATEDIFF(day, ' . $date2 . ',' . $date1 . ')';
    }

    public function getDateAddDaysExpression($date, $days)
    {
        return 'DATEADD(day, ' . $days . ', ' . $date . ')';
    }

    public function getDateSubDaysExpression($date, $days)
    {
        return 'DATEADD(day, -1 * ' . $days . ', ' . $date . ')';
    }

    public function getDateAddMonthExpression($date, $months)
    {
        return 'DATEADD(month, ' . $months . ', ' . $date . ')';
    }

    public function getDateSubMonthExpression($date, $months)
    {
        return 'DATEADD(month, -1 * ' . $months . ', ' . $date . ')';
    }

    /**
     * Whether the platform prefers identity columns for ID generation.
     * MsSql prefers "autoincrement" identity columns since sequences can only
     * be emulated with a table.
     *
     * @return boolean
     * @override
     */
    public function prefersIdentityColumns()
    {
        return true;
    }

    /**
     * Whether the platform supports identity columns.
     * MsSql supports this through AUTO_INCREMENT columns.
     *
     * @return boolean
     * @override
     */
    public function supportsIdentityColumns()
    {
        return true;
    }

    /**
     * Whether the platform supports releasing savepoints.
     *
     * @return boolean
     */
    public function supportsReleaseSavepoints()
    {
        return false;
    }

    /**
     * create a new database
     *
     * @param string $name name of the database that should be created
     * @return string
     * @override
     */
    public function getCreateDatabaseSQL($name)
    {
        return 'CREATE DATABASE ' . $name;
    }

    /**
     * drop an existing database
     *
     * @param string $name name of the database that should be dropped
     * @return string
     * @override
     */
    public function getDropDatabaseSQL($name)
    {
        return 'DROP DATABASE ' . $name;
    }

    /**
     * @override
     */
    public function supportsCreateDropDatabase()
    {
        return false;
    }

    /**
     * @override
     */
    public function getDropForeignKeySQL($foreignKey, $table)
    {
        if ($foreignKey instanceof \Doctrine\DBAL\Schema\ForeignKeyConstraint) {
            $foreignKey = $foreignKey->getQuotedName($this);
        }

        if ($table instanceof \Doctrine\DBAL\Schema\Table) {
            $table = $table->getQuotedName($this);
        }

        return 'ALTER TABLE ' . $table . ' DROP CONSTRAINT ' . $foreignKey;
    }

    /**
     * @override
     */
    public function getDropIndexSQL($index, $table=null)
    {
        if ($index instanceof \Doctrine\DBAL\Schema\Index) {
            $index = $index->getQuotedName($this);
        } else if (!is_string($index)) {
            throw new \InvalidArgumentException('AbstractPlatform::getDropIndexSQL() expects $index parameter to be string or \Doctrine\DBAL\Schema\Index.');
        }

        if (!isset($table)) {
            return 'DROP INDEX ' . $index;
        } else {
            if ($table instanceof \Doctrine\DBAL\Schema\Table) {
                $table = $table->getQuotedName($this);
            }

            return "IF EXISTS (SELECT * FROM sysobjects WHERE name = '$index')
						ALTER TABLE " . $table . " DROP CONSTRAINT " . $index . "
					ELSE
						DROP INDEX " . $index . " ON " . $table;
        }
    }

    /**
     * @override
     */
    protected function _getCreateTableSQL($tableName, array $columns, array $options = array())
    {
        // @todo does other code breaks because of this?
        // foce primary keys to be not null
        foreach ($columns as &$column) {
            if (isset($column['primary']) && $column['primary']) {
                $column['notnull'] = true;
            }
        }

        $columnListSql = $this->getColumnDeclarationListSQL($columns);

        if (isset($options['uniqueConstraints']) && !empty($options['uniqueConstraints'])) {
            foreach ($options['uniqueConstraints'] as $name => $definition) {
                $columnListSql .= ', ' . $this->getUniqueConstraintDeclarationSQL($name, $definition);
            }
        }

        if (isset($options['primary']) && !empty($options['primary'])) {
            $flags = '';
            if (isset($options['primary_index']) && $options['primary_index']->hasFlag('nonclustered')) {
                $flags = ' NONCLUSTERED';
            }
            $columnListSql .= ', PRIMARY KEY' . $flags . ' (' . implode(', ', array_unique(array_values($options['primary']))) . ')';
        }

        $query = 'CREATE TABLE ' . $tableName . ' (' . $columnListSql;

        $check = $this->getCheckDeclarationSQL($columns);
        if (!empty($check)) {
            $query .= ', ' . $check;
        }
        $query .= ')';

        $sql[] = $query;

        if (isset($options['indexes']) && !empty($options['indexes'])) {
            foreach ($options['indexes'] as $index) {
                $sql[] = $this->getCreateIndexSQL($index, $tableName);
            }
        }

        if (isset($options['foreignKeys'])) {
            foreach ((array) $options['foreignKeys'] as $definition) {
                $sql[] = $this->getCreateForeignKeySQL($definition, $tableName);
            }
        }

        return $sql;
    }

    /**
     * Get SQL to create an unnamed primary key constraint.
     *
     * @param Index $index
     * @param string|Table $table
     * @return string
     */
    public function getCreatePrimaryKeySQL(Index $index, $table)
    {
        $flags = '';
        if ($index->hasFlag('nonclustered')) {
            $flags = ' NONCLUSTERED';
        }
        return 'ALTER TABLE ' . $table . ' ADD PRIMARY KEY' . $flags . ' (' . $this->getIndexFieldDeclarationListSQL($index->getColumns()) . ')';
    }

    /**
     * @override
     */
    public function getUniqueConstraintDeclarationSQL($name, Index $index)
    {
        $constraint = parent::getUniqueConstraintDeclarationSQL($name, $index);

        $constraint = $this->_appendUniqueConstraintDefinition($constraint, $index);

        return $constraint;
    }

    /**
     * @override
     */
    public function getCreateIndexSQL(Index $index, $table)
    {
        $constraint = parent::getCreateIndexSQL($index, $table);

        if ($index->isUnique()) {
            $constraint = $this->_appendUniqueConstraintDefinition($constraint, $index);
        }

        return $constraint;
    }

    /**
     * @override
     */
    protected function getCreateIndexSQLFlags(Index $index)
    {
        $type = '';
        if ($index->isUnique()) {
            $type .= 'UNIQUE ';
        }

        if ($index->hasFlag('clustered')) {
            $type .= 'CLUSTERED ';
        } else if ($index->hasFlag('nonclustered')) {
            $type .= 'NONCLUSTERED ';
        }

        return $type;
    }

    /**
     * Extend unique key constraint with required filters
     *
     * @param string $sql
     * @param Index $index
     * @return string
     */
    private function _appendUniqueConstraintDefinition($sql, Index $index)
    {
        $fields = array();
        foreach ($index->getColumns() as $field => $definition) {
            if (!is_array($definition)) {
                $field = $definition;
            }

            $fields[] = $field . ' IS NOT NULL';
        }

        return $sql . ' WHERE ' . implode(' AND ', $fields);
    }

    /**
     * @override
     */
    public function getAlterTableSQL(TableDiff $diff)
    {
        $queryParts = array();
        $sql = array();
        $columnSql = array();

        if ($diff->newName !== false) {
            $queryParts[] = 'RENAME TO ' . $diff->newName;
        }

        foreach ($diff->addedColumns as $column) {
            if ($this->onSchemaAlterTableAddColumn($column, $diff, $columnSql)) {
                continue;
            }

            $queryParts[] = 'ADD ' . $this->getColumnDeclarationSQL($column->getQuotedName($this), $column->toArray());
        }

        foreach ($diff->removedColumns as $column) {
            if ($this->onSchemaAlterTableRemoveColumn($column, $diff, $columnSql)) {
                continue;
            }

            $queryParts[] = 'DROP COLUMN ' . $column->getQuotedName($this);
        }

        foreach ($diff->changedColumns as $columnDiff) {
            if ($this->onSchemaAlterTableChangeColumn($columnDiff, $diff, $columnSql)) {
                continue;
            }

            /* @var $columnDiff Doctrine\DBAL\Schema\ColumnDiff */
            $column = $columnDiff->column;
            $queryParts[] = 'ALTER COLUMN ' .
                    $this->getColumnDeclarationSQL($column->getQuotedName($this), $column->toArray());
        }

        foreach ($diff->renamedColumns as $oldColumnName => $column) {
            if ($this->onSchemaAlterTableRenameColumn($oldColumnName, $column, $diff, $columnSql)) {
                continue;
            }

            $sql[] = "sp_RENAME '". $diff->name. ".". $oldColumnName . "' , '".$column->getQuotedName($this)."', 'COLUMN'";
            $queryParts[] = 'ALTER COLUMN ' .
                    $this->getColumnDeclarationSQL($column->getQuotedName($this), $column->toArray());
        }

        $tableSql = array();

        if ($this->onSchemaAlterTable($diff, $tableSql)) {
            return array_merge($tableSql, $columnSql);
        }

        foreach ($queryParts as $query) {
            $sql[] = 'ALTER TABLE ' . $diff->name . ' ' . $query;
        }

        $sql = array_merge($sql, $this->_getAlterTableIndexForeignKeySQL($diff));

        return array_merge($sql, $tableSql, $columnSql);
    }

    /**
     * @override
     */
    public function getEmptyIdentityInsertSQL($quotedTableName, $quotedIdentifierColumnName)
    {
        return 'INSERT INTO ' . $quotedTableName . ' DEFAULT VALUES';
    }

    /**
     * @override
     */
    public function getShowDatabasesSQL()
    {
        return 'SHOW DATABASES';
    }

    /**
     * @override
     */
    public function getListTablesSQL()
    {
        // "sysdiagrams" table must be ignored as it's internal SQL Server table for Database Diagrams
        return "SELECT name FROM sysobjects WHERE type = 'U' AND name != 'sysdiagrams' ORDER BY name";
    }

    /**
     * @override
     */
    public function getListTableColumnsSQL($table, $database = null)
    {
        return "exec sp_columns @table_name = '" . $table . "'";
    }

    /**
     * @override
     */
    public function getListTableForeignKeysSQL($table, $database = null)
    {
        return "SELECT f.name AS ForeignKey,
                SCHEMA_NAME (f.SCHEMA_ID) AS SchemaName,
                OBJECT_NAME (f.parent_object_id) AS TableName,
                COL_NAME (fc.parent_object_id,fc.parent_column_id) AS ColumnName,
                SCHEMA_NAME (o.SCHEMA_ID) ReferenceSchemaName,
                OBJECT_NAME (f.referenced_object_id) AS ReferenceTableName,
                COL_NAME(fc.referenced_object_id,fc.referenced_column_id) AS ReferenceColumnName,
                f.delete_referential_action_desc,
                f.update_referential_action_desc
                FROM sys.foreign_keys AS f
                INNER JOIN sys.foreign_key_columns AS fc
                INNER JOIN sys.objects AS o ON o.OBJECT_ID = fc.referenced_object_id
                ON f.OBJECT_ID = fc.constraint_object_id
                WHERE OBJECT_NAME (f.parent_object_id) = '" . $table . "'";
    }

    /**
     * @override
     */
    public function getListTableIndexesSQL($table, $currentDatabase = null)
    {
        return "exec sp_helpindex '" . $table . "'";
    }

    /**
     * @override
     */
    public function getCreateViewSQL($name, $sql)
    {
        return 'CREATE VIEW ' . $name . ' AS ' . $sql;
    }

    /**
     * @override
     */
    public function getListViewsSQL($database)
    {
        return "SELECT name FROM sysobjects WHERE type = 'V' ORDER BY name";
    }

    /**
     * @override
     */
    public function getDropViewSQL($name)
    {
        return 'DROP VIEW ' . $name;
    }

    /**
     * Returns the regular expression operator.
     *
     * @return string
     * @override
     */
    public function getRegexpExpression()
    {
        return 'RLIKE';
    }

    /**
     * Returns global unique identifier
     *
     * @return string to get global unique identifier
     * @override
     */
    public function getGuidExpression()
    {
        return 'UUID()';
    }

    /**
     * @override
     */
    public function getLocateExpression($str, $substr, $startPos = false)
    {
        if ($startPos == false) {
            return 'CHARINDEX(' . $substr . ', ' . $str . ')';
        } else {
            return 'CHARINDEX(' . $substr . ', ' . $str . ', ' . $startPos . ')';
        }
    }

    /**
     * @override
     */
    public function getModExpression($expression1, $expression2)
    {
        return $expression1 . ' % ' . $expression2;
    }

    /**
     * @override
     */
    public function getTrimExpression($str, $pos = self::TRIM_UNSPECIFIED, $char = false)
    {
        $trimFn = '';

        if ( ! $char) {
            if ($pos == self::TRIM_LEADING) {
                $trimFn = 'LTRIM';
            } else if ($pos == self::TRIM_TRAILING) {
                $trimFn = 'RTRIM';
            } else {
                return 'LTRIM(RTRIM(' . $str . '))';
            }

            return $trimFn . '(' . $str . ')';
        } else {
            /** Original query used to get those expressions
              declare @c varchar(100) = 'xxxBarxxx', @trim_char char(1) = 'x';
              declare @pat varchar(10) = '%[^' + @trim_char + ']%';
              select @c as string
              , @trim_char as trim_char
              , stuff(@c, 1, patindex(@pat, @c) - 1, null) as trim_leading
              , reverse(stuff(reverse(@c), 1, patindex(@pat, reverse(@c)) - 1, null)) as trim_trailing
              , reverse(stuff(reverse(stuff(@c, 1, patindex(@pat, @c) - 1, null)), 1, patindex(@pat, reverse(stuff(@c, 1, patindex(@pat, @c) - 1, null))) - 1, null)) as trim_both;
             */
            $pattern = "'%[^' + $char + ']%'";

            if ($pos == self::TRIM_LEADING) {
                return 'stuff(' . $str . ', 1, patindex(' . $pattern . ', ' . $str . ') - 1, null)';
            } else if ($pos == self::TRIM_TRAILING) {
                return 'reverse(stuff(reverse(' . $str . '), 1, patindex(' . $pattern . ', reverse(' . $str . ')) - 1, null))';
            } else {
                return 'reverse(stuff(reverse(stuff(' . $str . ', 1, patindex(' . $pattern . ', ' . $str . ') - 1, null)), 1, patindex(' . $pattern . ', reverse(stuff(' . $str . ', 1, patindex(' . $pattern . ', ' . $str . ') - 1, null))) - 1, null))';
            }
        }
    }

    /**
     * @override
     */
    public function getConcatExpression()
    {
        $args = func_get_args();
        return '(' . implode(' + ', $args) . ')';
    }

    public function getListDatabasesSQL()
    {
        return 'SELECT * FROM SYS.DATABASES';
    }

    /**
     * @override
     */
    public function getSubstringExpression($value, $from, $len = null)
    {
        if (!is_null($len)) {
            return 'SUBSTRING(' . $value . ', ' . $from . ', ' . $len . ')';
        }
        return 'SUBSTRING(' . $value . ', ' . $from . ', LEN(' . $value . ') - ' . $from . ' + 1)';
    }

    /**
     * @override
     */
    public function getLengthExpression($column)
    {
        return 'LEN(' . $column . ')';
    }

    /**
     * @override
     */
    public function getSetTransactionIsolationSQL($level)
    {
        return 'SET TRANSACTION ISOLATION LEVEL ' . $this->_getTransactionIsolationLevelSQL($level);
    }

    /**
     * @override
     */
    public function getIntegerTypeDeclarationSQL(array $field)
    {
        return 'INT' . $this->_getCommonIntegerTypeDeclarationSQL($field);
    }

    /**
     * @override
     */
    public function getBigIntTypeDeclarationSQL(array $field)
    {
        return 'BIGINT' . $this->_getCommonIntegerTypeDeclarationSQL($field);
    }

    /**
     * @override
     */
    public function getSmallIntTypeDeclarationSQL(array $field)
    {
        return 'SMALLINT' . $this->_getCommonIntegerTypeDeclarationSQL($field);
    }

    /**
     * Decleration for a UNIQUEIDENTIFIER (GUID) field in SQL Server
     *
     * @param array $field
     * @return string
     */
    public function getGuidTypeDeclartionSQL(array $field)
    {
        return 'UNIQUEIDENTIFIER';
    }

    /** @override */
    protected function getVarcharTypeDeclarationSQLSnippet($length, $fixed)
    {
        return $fixed ? ($length ? 'NCHAR(' . $length . ')' : 'CHAR(255)') : ($length ? 'NVARCHAR(' . $length . ')' : 'NVARCHAR(255)');
    }

    /** @override */
    public function getClobTypeDeclarationSQL(array $field)
    {
        return 'TEXT';
    }

    /**
     * @override
     */
    protected function _getCommonIntegerTypeDeclarationSQL(array $columnDef)
    {
        $autoinc = '';
        if (!empty($columnDef['autoincrement'])) {
            $autoinc = ' IDENTITY';
        }
        $unsigned = (isset($columnDef['unsigned']) && $columnDef['unsigned']) ? ' UNSIGNED' : '';

        return $unsigned . $autoinc;
    }

    /**
     * @override
     */
    public function getDateTimeTypeDeclarationSQL(array $fieldDeclaration)
    {
        return 'DATETIME';
    }

    /**
     * @override
     */
    public function getDateTypeDeclarationSQL(array $fieldDeclaration)
    {
        return 'DATETIME';
    }

    /**
     * @override
     */
    public function getTimeTypeDeclarationSQL(array $fieldDeclaration)
    {
        return 'DATETIME';
    }

    /**
     * @override
     */
    public function getBooleanTypeDeclarationSQL(array $field)
    {
        return 'BIT';
    }

    /**
     * Adds an adapter-specific LIMIT clause to the SELECT statement.
     *
     * @param string $query
     * @param integer $limit
     * @param integer $offset
     * @link http://lists.bestpractical.com/pipermail/rt-devel/2005-June/007339.html
     * @return string
     */
    protected function doModifyLimitQuery($query, $limit, $offset = null)
    {
        if ($limit > 0) {
            if ($offset == 0) {
                $query = preg_replace('/^(SELECT\s(DISTINCT\s)?)/i', '\1TOP ' . $limit . ' ', $query);
            } else {
                $orderby = stristr($query, 'ORDER BY');

                if ( ! $orderby) {
                    $over = 'ORDER BY (SELECT 0)';
                } else {
                    $over = preg_replace('/\"[^,]*\".\"([^,]*)\"/i', '"inner_tbl"."$1"', $orderby);
                }

                // Remove ORDER BY clause from $query
                $query = preg_replace('/\s+ORDER BY(.*)/', '', $query);
                $query = preg_replace('/^SELECT\s/', '', $query);

                $start = $offset + 1;
                $end = $offset + $limit;

                $query = "SELECT * FROM (SELECT ROW_NUMBER() OVER ($over) AS \"doctrine_rownum\", $query) AS doctrine_tbl WHERE \"doctrine_rownum\" BETWEEN $start AND $end";
            }
        }

        return $query;
    }

    /**
     * @override
     */
    public function supportsLimitOffset()
    {
        return false;
    }

    /**
     * @override
     */
    public function convertBooleans($item)
    {
        if (is_array($item)) {
            foreach ($item as $key => $value) {
                if (is_bool($value) || is_numeric($item)) {
                    $item[$key] = ($value) ? 1 : 0;
                }
            }
        } else {
            if (is_bool($item) || is_numeric($item)) {
                $item = ($item) ? 1 : 0;
            }
        }
        return $item;
    }

    /**
     * @override
     */
    public function getCreateTemporaryTableSnippetSQL()
    {
        return "CREATE TABLE";
    }

    /**
     * @override
     */
    public function getTemporaryTableName($tableName)
    {
        return '#' . $tableName;
    }

    /**
     * @override
     */
    public function getDateTimeFormatString()
    {
        return 'Y-m-d H:i:s.000';
    }

    /**
     * @override
     */
    public function getDateFormatString()
    {
        return 'Y-m-d H:i:s.000';
    }

    /**
     * @override
     */
    public function getTimeFormatString()
    {
        return 'Y-m-d H:i:s.000';
    }

    /**
     * @override
     */
    public function getDateTimeTzFormatString()
    {
        return $this->getDateTimeFormatString();
    }

    /**
     * Get the platform name for this instance
     *
     * @return string
     */
    public function getName()
    {
        return 'mssql';
    }

    /**
     * @override
     */
    protected function initializeDoctrineTypeMappings()
    {
        $this->doctrineTypeMapping = array(
            'bigint' => 'bigint',
            'numeric' => 'decimal',
            'bit' => 'boolean',
            'smallint' => 'smallint',
            'decimal' => 'decimal',
            'smallmoney' => 'integer',
            'int' => 'integer',
            'tinyint' => 'smallint',
            'money' => 'integer',
            'float' => 'float',
            'real' => 'float',
            'double' => 'float',
            'double precision' => 'float',
            'datetimeoffset' => 'datetimetz',
            'smalldatetime' => 'datetime',
            'datetime' => 'datetime',
            'char' => 'string',
            'varchar' => 'string',
            'text' => 'text',
            'nchar' => 'string',
            'nvarchar' => 'string',
            'ntext' => 'text',
            'binary' => 'text',
            'varbinary' => 'blob',
            'image' => 'text',
            'uniqueidentifier' => 'guid',
        );
    }

    /**
     * Generate SQL to create a new savepoint
     *
     * @param string $savepoint
     * @return string
     */
    public function createSavePoint($savepoint)
    {
        return 'SAVE TRANSACTION ' . $savepoint;
    }

    /**
     * Generate SQL to release a savepoint
     *
     * @param string $savepoint
     * @return string
     */
    public function releaseSavePoint($savepoint)
    {
        return '';
    }

    /**
     * Generate SQL to rollback a savepoint
     *
     * @param string $savepoint
     * @return string
     */
    public function rollbackSavePoint($savepoint)
    {
        return 'ROLLBACK TRANSACTION ' . $savepoint;
    }

    /**
     * @override
     */
    public function appendLockHint($fromClause, $lockMode)
    {
        // @todo coorect
        if ($lockMode == \Doctrine\DBAL\LockMode::PESSIMISTIC_READ) {
            return $fromClause . ' WITH (tablockx)';
        } else if ($lockMode == \Doctrine\DBAL\LockMode::PESSIMISTIC_WRITE) {
            return $fromClause . ' WITH (tablockx)';
        } else {
            return $fromClause;
        }
    }

    /**
     * @override
     */
    public function getForUpdateSQL()
    {
        return ' ';
    }

    protected function getReservedKeywordsClass()
    {
        return 'Doctrine\DBAL\Platforms\Keywords\MsSQLKeywords';
    }

    /**
     * {@inheritDoc}
     */
    public function quoteSingleIdentifier($str)
    {
        return "[" . str_replace("]", "][", $str) . "]";
    }

    public function getTruncateTableSQL($tableName, $cascade = false)
    {
        return 'TRUNCATE TABLE '.$tableName;
    }

    /**
     * Gets the SQL Snippet used to declare a BLOB column type.
     */
    public function getBlobTypeDeclarationSQL(array $field)
    {
        return 'VARBINARY(MAX)';
    }
}