DatabaseMssql.php

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<?php
class DatabaseMssql extends DatabaseBase {
    var $mInsertId = null;
    var $mLastResult = null;
    var $mAffectedRows = null;

    var $mPort;

    function cascadingDeletes() {
        return true;
    }

    function cleanupTriggers() {
        return true;
    }

    function strictIPs() {
        return true;
    }

    function realTimestamps() {
        return true;
    }

    function implicitGroupby() {
        return false;
    }

    function implicitOrderby() {
        return false;
    }

    function functionalIndexes() {
        return true;
    }

    function unionSupportsOrderAndLimit() {
        return false;
    }

    function open( $server, $user, $password, $dbName ) {
        # Test for driver support, to avoid suppressed fatal error
        if ( !function_exists( 'sqlsrv_connect' ) ) {
            throw new DBConnectionError( $this, "MS Sql Server Native (sqlsrv) functions missing. You can download the driver from: http://go.microsoft.com/fwlink/?LinkId=123470\n" );
        }

        global $wgDBport;

        if ( !strlen( $user ) ) { # e.g. the class is being loaded
            return;
        }

        $this->close();
        $this->mServer = $server;
        $this->mPort = $wgDBport;
        $this->mUser = $user;
        $this->mPassword = $password;
        $this->mDBname = $dbName;

        $connectionInfo = array();

        if ( $dbName ) {
            $connectionInfo['Database'] = $dbName;
        }

        // Start NT Auth Hack
        // Quick and dirty work around to provide NT Auth designation support.
        // Current solution requires installer to know to input 'ntauth' for both username and password
        // to trigger connection via NT Auth. - ugly, ugly, ugly
        // TO-DO: Make this better and add NT Auth choice to MW installer when SQL Server option is chosen.
        $ntAuthUserTest = strtolower( $user );
        $ntAuthPassTest = strtolower( $password );

        // Decide which auth scenerio to use
        if ( $ntAuthPassTest == 'ntauth' && $ntAuthUserTest == 'ntauth' ) {
            // Don't add credentials to $connectionInfo
        } else {
            $connectionInfo['UID'] = $user;
            $connectionInfo['PWD'] = $password;
        }
        // End NT Auth Hack

        wfSuppressWarnings();
        $this->mConn = sqlsrv_connect( $server, $connectionInfo );
        wfRestoreWarnings();

        if ( $this->mConn === false ) {
            wfDebug( "DB connection error\n" );
            wfDebug( "Server: $server, Database: $dbName, User: $user, Password: " . substr( $password, 0, 3 ) . "...\n" );
            wfDebug( $this->lastError() . "\n" );
            return false;
        }

        $this->mOpened = true;
        return $this->mConn;
    }

    protected function closeConnection() {
        return sqlsrv_close( $this->mConn );
    }

    protected function doQuery( $sql ) {
        wfDebug( "SQL: [$sql]\n" );
        $this->offset = 0;

        // several extensions seem to think that all databases support limits via LIMIT N after the WHERE clause
        // well, MSSQL uses SELECT TOP N, so to catch any of those extensions we'll do a quick check for a LIMIT
        // clause and pass $sql through $this->LimitToTopN() which parses the limit clause and passes the result to
        // $this->limitResult();
        if ( preg_match( '/\bLIMIT\s*/i', $sql ) ) {
            // massage LIMIT -> TopN
            $sql = $this->LimitToTopN( $sql );
        }

        // MSSQL doesn't have EXTRACT(epoch FROM XXX)
        if ( preg_match( '#\bEXTRACT\s*?\(\s*?EPOCH\s+FROM\b#i', $sql, $matches ) ) {
            // This is same as UNIX_TIMESTAMP, we need to calc # of seconds from 1970
            $sql = str_replace( $matches[0], "DATEDIFF(s,CONVERT(datetime,'1/1/1970'),", $sql );
        }

        // perform query
        $stmt = sqlsrv_query( $this->mConn, $sql );
        if ( $stmt == false ) {
            $message = "A database error has occurred. Did you forget to run maintenance/update.php after upgrading?  See: http://www.mediawiki.org/wiki/Manual:Upgrading#Run_the_update_script\n" .
                "Query: " . htmlentities( $sql ) . "\n" .
                "Function: " . __METHOD__ . "\n";
            // process each error (our driver will give us an array of errors unlike other providers)
            foreach ( sqlsrv_errors() as $error ) {
                $message .= $message . "ERROR[" . $error['code'] . "] " . $error['message'] . "\n";
            }

            throw new DBUnexpectedError( $this, $message );
        }
        // remember number of rows affected
        $this->mAffectedRows = sqlsrv_rows_affected( $stmt );

        // if it is a SELECT statement, or an insert with a request to output something we want to return a row.
        if ( ( preg_match( '#\bSELECT\s#i', $sql ) ) ||
            ( preg_match( '#\bINSERT\s#i', $sql ) && preg_match( '#\bOUTPUT\s+INSERTED\b#i', $sql ) ) ) {
            // this is essentially a rowset, but Mediawiki calls these 'result'
            // the rowset owns freeing the statement
            $res = new MssqlResult( $stmt );
        } else {
            // otherwise we simply return it was successful, failure throws an exception
            $res = true;
        }
        return $res;
    }

    function freeResult( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        $res->free();
    }

    function fetchObject( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        $row = $res->fetch( 'OBJECT' );
        return $row;
    }

    function getErrors() {
        $strRet = '';
        $retErrors = sqlsrv_errors( SQLSRV_ERR_ALL );
        if ( $retErrors != null ) {
            foreach ( $retErrors as $arrError ) {
                $strRet .= "SQLState: " . $arrError['SQLSTATE'] . "\n";
                $strRet .= "Error Code: " . $arrError['code'] . "\n";
                $strRet .= "Message: " . $arrError['message'] . "\n";
            }
        } else {
            $strRet = "No errors found";
        }
        return $strRet;
    }

    function fetchRow( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        $row = $res->fetch( SQLSRV_FETCH_BOTH );
        return $row;
    }

    function numRows( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        return ( $res ) ? $res->numrows() : 0;
    }

    function numFields( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        return ( $res ) ? $res->numfields() : 0;
    }

    function fieldName( $res, $n ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        return ( $res ) ? $res->fieldname( $n ) : 0;
    }

    function insertId() {
        return $this->mInsertId;
    }

    function dataSeek( $res, $row ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        return ( $res ) ? $res->seek( $row ) : false;
    }

    function lastError() {
        if ( $this->mConn ) {
            return $this->getErrors();
        } else {
            return "No database connection";
        }
    }

    function lastErrno() {
        $err = sqlsrv_errors( SQLSRV_ERR_ALL );
        if ( $err[0] ) {
            return $err[0]['code'];
        } else {
            return 0;
        }
    }

    function affectedRows() {
        return $this->mAffectedRows;
    }

    function select( $table, $vars, $conds = '', $fname = __METHOD__, $options = array(), $join_conds = array() )
    {
        $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
        if ( isset( $options['EXPLAIN'] ) ) {
            sqlsrv_query( $this->mConn, "SET SHOWPLAN_ALL ON;" );
            $ret = $this->query( $sql, $fname );
            sqlsrv_query( $this->mConn, "SET SHOWPLAN_ALL OFF;" );
            return $ret;
        }
        return $this->query( $sql, $fname );
    }

    function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__, $options = array(), $join_conds = array() ) {
        if ( isset( $options['EXPLAIN'] ) ) {
            unset( $options['EXPLAIN'] );
        }
        return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
    }

    function estimateRowCount( $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array() ) {
        $options['EXPLAIN'] = true;// http://msdn2.microsoft.com/en-us/library/aa259203.aspx
        $res = $this->select( $table, $vars, $conds, $fname, $options );

        $rows = -1;
        if ( $res ) {
            $row = $this->fetchRow( $res );
            if ( isset( $row['EstimateRows'] ) ) {
                $rows = $row['EstimateRows'];
            }
        }
        return $rows;
    }

    function indexInfo( $table, $index, $fname = __METHOD__ ) {
        # This does not return the same info as MYSQL would, but that's OK because MediaWiki never uses the
        # returned value except to check for the existance of indexes.
        $sql = "sp_helpindex '" . $table . "'";
        $res = $this->query( $sql, $fname );
        if ( !$res ) {
            return null;
        }

        $result = array();
        foreach ( $res as $row ) {
            if ( $row->index_name == $index ) {
                $row->Non_unique = !stristr( $row->index_description, "unique" );
                $cols = explode( ", ", $row->index_keys );
                foreach ( $cols as $col ) {
                    $row->Column_name = trim( $col );
                    $result[] = clone $row;
                }
            } elseif ( $index == 'PRIMARY' && stristr( $row->index_description, 'PRIMARY' ) ) {
                $row->Non_unique = 0;
                $cols = explode( ", ", $row->index_keys );
                foreach ( $cols as $col ) {
                    $row->Column_name = trim( $col );
                    $result[] = clone $row;
                }
            }
        }
        return empty( $result ) ? false : $result;
    }

    function insert( $table, $arrToInsert, $fname = __METHOD__, $options = array() ) {
        # No rows to insert, easy just return now
        if ( !count( $arrToInsert ) ) {
            return true;
        }

        if ( !is_array( $options ) ) {
            $options = array( $options );
        }

        $table = $this->tableName( $table );

        if ( !( isset( $arrToInsert[0] ) && is_array( $arrToInsert[0] ) ) ) {// Not multi row
            $arrToInsert = array( 0 => $arrToInsert );// make everything multi row compatible
        }

        $allOk = true;

        // We know the table we're inserting into, get its identity column
        $identity = null;
        $tableRaw = preg_replace( '#\[([^\]]*)\]#', '$1', $table ); // strip matching square brackets from table name
        $res = $this->doQuery( "SELECT NAME AS idColumn FROM SYS.IDENTITY_COLUMNS WHERE OBJECT_NAME(OBJECT_ID)='{$tableRaw}'" );
        if ( $res && $res->numrows() ) {
            // There is an identity for this table.
            $identity = array_pop( $res->fetch( SQLSRV_FETCH_ASSOC ) );
        }
        unset( $res );

        foreach ( $arrToInsert as $a ) {
            // start out with empty identity column, this is so we can return it as a result of the insert logic
            $sqlPre = '';
            $sqlPost = '';
            $identityClause = '';

            // if we have an identity column
            if ( $identity ) {
                // iterate through
                foreach ( $a as $k => $v ) {
                    if ( $k == $identity ) {
                        if ( !is_null( $v ) ) {
                            // there is a value being passed to us, we need to turn on and off inserted identity
                            $sqlPre = "SET IDENTITY_INSERT $table ON;";
                            $sqlPost = ";SET IDENTITY_INSERT $table OFF;";

                        } else {
                            // we can't insert NULL into an identity column, so remove the column from the insert.
                            unset( $a[$k] );
                        }
                    }
                }
                $identityClause = "OUTPUT INSERTED.$identity "; // we want to output an identity column as result
            }

            $keys = array_keys( $a );

            // INSERT IGNORE is not supported by SQL Server
            // remove IGNORE from options list and set ignore flag to true
            $ignoreClause = false;
            foreach ( $options as $k => $v ) {
                if ( strtoupper( $v ) == "IGNORE" ) {
                    unset( $options[$k] );
                    $ignoreClause = true;
                }
            }

            // translate MySQL INSERT IGNORE to something SQL Server can use
            // example:
            // MySQL: INSERT IGNORE INTO user_groups (ug_user,ug_group) VALUES ('1','sysop')
            // MSSQL: IF NOT EXISTS (SELECT * FROM user_groups WHERE ug_user = '1') INSERT INTO user_groups (ug_user,ug_group) VALUES ('1','sysop')
            if ( $ignoreClause ) {
                $prival = $a[$keys[0]];
                $sqlPre .= "IF NOT EXISTS (SELECT * FROM $table WHERE $keys[0] = '$prival')";
            }

            // Build the actual query
            $sql = $sqlPre . 'INSERT ' . implode( ' ', $options ) .
                " INTO $table (" . implode( ',', $keys ) . ") $identityClause VALUES (";

            $first = true;
            foreach ( $a as $value ) {
                if ( $first ) {
                    $first = false;
                } else {
                    $sql .= ',';
                }
                if ( is_string( $value ) ) {
                    $sql .= $this->addQuotes( $value );
                } elseif ( is_null( $value ) ) {
                    $sql .= 'null';
                } elseif ( is_array( $value ) || is_object( $value ) ) {
                    if ( is_object( $value ) && strtolower( get_class( $value ) ) == 'blob' ) {
                        $sql .= $this->addQuotes( $value );
                    } else {
                        $sql .= $this->addQuotes( serialize( $value ) );
                    }
                } else {
                    $sql .= $value;
                }
            }
            $sql .= ')' . $sqlPost;

            // Run the query
            $ret = sqlsrv_query( $this->mConn, $sql );

            if ( $ret === false ) {
                throw new DBQueryError( $this, $this->getErrors(), $this->lastErrno(), $sql, $fname );
            } elseif ( $ret != null ) {
                // remember number of rows affected
                $this->mAffectedRows = sqlsrv_rows_affected( $ret );
                if ( !is_null( $identity ) ) {
                    // then we want to get the identity column value we were assigned and save it off
                    $row = sqlsrv_fetch_object( $ret );
                    $this->mInsertId = $row->$identity;
                }
                sqlsrv_free_stmt( $ret );
                continue;
            }
            $allOk = false;
        }
        return $allOk;
    }

    function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
        $insertOptions = array(), $selectOptions = array() ) {
        $ret = parent::insertSelect( $destTable, $srcTable, $varMap, $conds, $fname, $insertOptions, $selectOptions );

        if ( $ret === false ) {
            throw new DBQueryError( $this, $this->getErrors(), $this->lastErrno(), /*$sql*/ '', $fname );
        } elseif ( $ret != null ) {
            // remember number of rows affected
            $this->mAffectedRows = sqlsrv_rows_affected( $ret );
            return $ret;
        }
        return null;
    }

    function nextSequenceValue( $seqName ) {
        if ( !$this->tableExists( 'sequence_' . $seqName ) ) {
            sqlsrv_query( $this->mConn, "CREATE TABLE [sequence_$seqName] (id INT NOT NULL IDENTITY PRIMARY KEY, junk varchar(10) NULL)" );
        }
        sqlsrv_query( $this->mConn, "INSERT INTO [sequence_$seqName] (junk) VALUES ('')" );
        $ret = sqlsrv_query( $this->mConn, "SELECT TOP 1 id FROM [sequence_$seqName] ORDER BY id DESC" );
        $row = sqlsrv_fetch_array( $ret, SQLSRV_FETCH_ASSOC );// KEEP ASSOC THERE, weird weird bug dealing with the return value if you don't

        sqlsrv_free_stmt( $ret );
        $this->mInsertId = $row['id'];
        return $row['id'];
    }

    function currentSequenceValue( $seqName ) {
        $ret = sqlsrv_query( $this->mConn, "SELECT TOP 1 id FROM [sequence_$seqName] ORDER BY id DESC" );
        if ( $ret !== false ) {
            $row = sqlsrv_fetch_array( $ret );
            sqlsrv_free_stmt( $ret );
            return $row['id'];
        } else {
            return $this->nextSequenceValue( $seqName );
        }
    }

    # Returns the size of a text field, or -1 for "unlimited"
    function textFieldSize( $table, $field ) {
        $table = $this->tableName( $table );
        $sql = "SELECT CHARACTER_MAXIMUM_LENGTH,DATA_TYPE FROM INFORMATION_SCHEMA.Columns
            WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'";
        $res = $this->query( $sql );
        $row = $this->fetchRow( $res );
        $size = -1;
        if ( strtolower( $row['DATA_TYPE'] ) != 'text' ) {
            $size = $row['CHARACTER_MAXIMUM_LENGTH'];
        }
        return $size;
    }

    function limitResult( $sql, $limit, $offset = false ) {
        if ( $offset === false || $offset == 0 ) {
            if ( strpos( $sql, "SELECT" ) === false ) {
                return "TOP {$limit} " . $sql;
            } else {
                return preg_replace( '/\bSELECT(\s*DISTINCT)?\b/Dsi', 'SELECT$1 TOP ' . $limit, $sql, 1 );
            }
        } else {
            $sql = '
                SELECT * FROM (
                    SELECT sub2.*, ROW_NUMBER() OVER(ORDER BY sub2.line2) AS line3 FROM (
                        SELECT 1 AS line2, sub1.* FROM (' . $sql . ') AS sub1
                    ) as sub2
                ) AS sub3
                WHERE line3 BETWEEN ' . ( $offset + 1 ) . ' AND ' . ( $offset + $limit );
            return $sql;
        }
    }

    // If there is a limit clause, parse it, strip it, and pass the remaining sql through limitResult()
    // with the appropriate parameters. Not the prettiest solution, but better than building a whole new parser.
    // This exists becase there are still too many extensions that don't use dynamic sql generation.
    function LimitToTopN( $sql ) {
        // Matches: LIMIT {[offset,] row_count | row_count OFFSET offset}
        $pattern = '/\bLIMIT\s+((([0-9]+)\s*,\s*)?([0-9]+)(\s+OFFSET\s+([0-9]+))?)/i';
        if ( preg_match( $pattern, $sql, $matches ) ) {
            // row_count = $matches[4]
            $row_count = $matches[4];
            // offset = $matches[3] OR $matches[6]
            $offset = $matches[3] or
                $offset = $matches[6] or
                $offset = false;

            // strip the matching LIMIT clause out
            $sql = str_replace( $matches[0], '', $sql );
            return $this->limitResult( $sql, $row_count, $offset );
        }
        return $sql;
    }

    function timestamp( $ts = 0 ) {
        return wfTimestamp( TS_ISO_8601, $ts );
    }

    public function getSoftwareLink() {
        return "[{{int:version-db-mssql-url}} MS SQL Server]";
    }

    function getServerVersion() {
        $server_info = sqlsrv_server_info( $this->mConn );
        $version = 'Error';
        if ( isset( $server_info['SQLServerVersion'] ) ) {
            $version = $server_info['SQLServerVersion'];
        }
        return $version;
    }

    function tableExists( $table, $fname = __METHOD__, $schema = false ) {
        $res = sqlsrv_query( $this->mConn, "SELECT * FROM information_schema.tables
            WHERE table_type='BASE TABLE' AND table_name = '$table'" );
        if ( $res === false ) {
            print "Error in tableExists query: " . $this->getErrors();
            return false;
        }
        if ( sqlsrv_fetch( $res ) ) {
            return true;
        } else {
            return false;
        }
    }

    function fieldExists( $table, $field, $fname = __METHOD__ ) {
        $table = $this->tableName( $table );
        $res = sqlsrv_query( $this->mConn, "SELECT DATA_TYPE FROM INFORMATION_SCHEMA.Columns
            WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
        if ( $res === false ) {
            print "Error in fieldExists query: " . $this->getErrors();
            return false;
        }
        if ( sqlsrv_fetch( $res ) ) {
            return true;
        } else {
            return false;
        }
    }

    function fieldInfo( $table, $field ) {
        $table = $this->tableName( $table );
        $res = sqlsrv_query( $this->mConn, "SELECT * FROM INFORMATION_SCHEMA.Columns
            WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
        if ( $res === false ) {
            print "Error in fieldInfo query: " . $this->getErrors();
            return false;
        }
        $meta = $this->fetchRow( $res );
        if ( $meta ) {
            return new MssqlField( $meta );
        }
        return false;
    }

    protected function doBegin( $fname = __METHOD__ ) {
        sqlsrv_begin_transaction( $this->mConn );
        $this->mTrxLevel = 1;
    }

    protected function doCommit( $fname = __METHOD__ ) {
        sqlsrv_commit( $this->mConn );
        $this->mTrxLevel = 0;
    }

    protected function doRollback( $fname = __METHOD__ ) {
        sqlsrv_rollback( $this->mConn );
        $this->mTrxLevel = 0;
    }

    private function escapeIdentifier( $identifier ) {
        if ( strlen( $identifier ) == 0 ) {
            throw new MWException( "An identifier must not be empty" );
        }
        if ( strlen( $identifier ) > 128 ) {
            throw new MWException( "The identifier '$identifier' is too long (max. 128)" );
        }
        if ( ( strpos( $identifier, '[' ) !== false ) || ( strpos( $identifier, ']' ) !== false ) ) {
            // It may be allowed if you quoted with double quotation marks, but that would break if QUOTED_IDENTIFIER is OFF
            throw new MWException( "You can't use square brackers in the identifier '$identifier'" );
        }
        return "[$identifier]";
    }

    function initial_setup( $dbName, $newUser, $loginPassword ) {
        $dbName = $this->escapeIdentifier( $dbName );

        // It is not clear what can be used as a login,
        // From http://msdn.microsoft.com/en-us/library/ms173463.aspx
        // a sysname may be the same as an identifier.
        $newUser = $this->escapeIdentifier( $newUser );
        $loginPassword = $this->addQuotes( $loginPassword );

        $this->doQuery( "CREATE DATABASE $dbName;" );
        $this->doQuery( "USE $dbName;" );
        $this->doQuery( "CREATE SCHEMA $dbName;" );
        $this->doQuery( "
                        CREATE
                            LOGIN $newUser
                        WITH
                            PASSWORD=$loginPassword
                        ;
                    " );
        $this->doQuery( "
                        CREATE
                            USER $newUser
                        FOR
                            LOGIN $newUser
                        WITH
                            DEFAULT_SCHEMA=$dbName
                        ;
                    " );
        $this->doQuery( "
                        GRANT
                            BACKUP DATABASE,
                            BACKUP LOG,
                            CREATE DEFAULT,
                            CREATE FUNCTION,
                            CREATE PROCEDURE,
                            CREATE RULE,
                            CREATE TABLE,
                            CREATE VIEW,
                            CREATE FULLTEXT CATALOG
                        ON
                            DATABASE::$dbName
                        TO $newUser
                        ;
                    " );
        $this->doQuery( "
                        GRANT
                            CONTROL
                        ON
                            SCHEMA::$dbName
                        TO $newUser
                        ;
                    " );
    }

    function encodeBlob( $b ) {
    // we can't have zero's and such, this is a simple encoding to make sure we don't barf
        return base64_encode( $b );
    }

    function decodeBlob( $b ) {
    // we can't have zero's and such, this is a simple encoding to make sure we don't barf
    return base64_decode( $b );
    }

    function tableNamesWithUseIndexOrJOIN( $tables, $use_index = array(), $join_conds = array() ) {
        $ret = array();
        $retJOIN = array();
        $use_index_safe = is_array( $use_index ) ? $use_index : array();
        $join_conds_safe = is_array( $join_conds ) ? $join_conds : array();
        foreach ( $tables as $table ) {
            // Is there a JOIN and INDEX clause for this table?
            if ( isset( $join_conds_safe[$table] ) && isset( $use_index_safe[$table] ) ) {
                $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
                $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
                $tableClause .= ' ON (' . $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND ) . ')';
                $retJOIN[] = $tableClause;
            // Is there an INDEX clause?
            } elseif ( isset( $use_index_safe[$table] ) ) {
                $tableClause = $this->tableName( $table );
                $tableClause .= ' ' . $this->useIndexClause( implode( ',', (array)$use_index_safe[$table] ) );
                $ret[] = $tableClause;
            // Is there a JOIN clause?
            } elseif ( isset( $join_conds_safe[$table] ) ) {
                $tableClause = $join_conds_safe[$table][0] . ' ' . $this->tableName( $table );
                $tableClause .= ' ON (' . $this->makeList( (array)$join_conds_safe[$table][1], LIST_AND ) . ')';
                $retJOIN[] = $tableClause;
            } else {
                $tableClause = $this->tableName( $table );
                $ret[] = $tableClause;
            }
        }
        // We can't separate explicit JOIN clauses with ',', use ' ' for those
        $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
        $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
        // Compile our final table clause
        return implode( ' ', array( $straightJoins, $otherJoins ) );
    }

    function strencode( $s ) { # Should not be called by us
        return str_replace( "'", "''", $s );
    }

    function addQuotes( $s ) {
        if ( $s instanceof Blob ) {
            return "'" . $s->fetch( $s ) . "'";
        } else {
            return parent::addQuotes( $s );
        }
    }

    public function addIdentifierQuotes( $s ) {
        // http://msdn.microsoft.com/en-us/library/aa223962.aspx
        return '[' . $s . ']';
    }

    public function isQuotedIdentifier( $name ) {
        return $name[0] == '[' && substr( $name, -1, 1 ) == ']';
    }

    function selectDB( $db ) {
        return ( $this->query( "SET DATABASE $db" ) !== false );
    }

    function makeSelectOptions( $options ) {
        $tailOpts = '';
        $startOpts = '';

        $noKeyOptions = array();
        foreach ( $options as $key => $option ) {
            if ( is_numeric( $key ) ) {
                $noKeyOptions[$option] = true;
            }
        }

        $tailOpts .= $this->makeGroupByWithHaving( $options );

        $tailOpts .= $this->makeOrderBy( $options );

        if ( isset( $noKeyOptions['DISTINCT'] ) && isset( $noKeyOptions['DISTINCTROW'] ) ) {
            $startOpts .= 'DISTINCT';
        }

        // we want this to be compatible with the output of parent::makeSelectOptions()
        return array( $startOpts, '', $tailOpts, '' );
    }

    function getType() {
        return 'mssql';
    }

    function buildConcat( $stringList ) {
        return implode( ' + ', $stringList );
    }

    public function getSearchEngine() {
        return "SearchMssql";
    }

    public function getInfinity() {
        return '3000-01-31 00:00:00.000';
    }

} // end DatabaseMssql class

class MssqlField implements Field {
    private $name, $tablename, $default, $max_length, $nullable, $type;
    function __construct( $info ) {
        $this->name = $info['COLUMN_NAME'];
        $this->tablename = $info['TABLE_NAME'];
        $this->default = $info['COLUMN_DEFAULT'];
        $this->max_length = $info['CHARACTER_MAXIMUM_LENGTH'];
        $this->nullable = !( strtolower( $info['IS_NULLABLE'] ) == 'no' );
        $this->type = $info['DATA_TYPE'];
    }

    function name() {
        return $this->name;
    }

    function tableName() {
        return $this->tableName;
    }

    function defaultValue() {
        return $this->default;
    }

    function maxLength() {
        return $this->max_length;
    }

    function isNullable() {
        return $this->nullable;
    }

    function type() {
        return $this->type;
    }
}

class MssqlResult {

    public function __construct( $queryresult = false ) {
        $this->mCursor = 0;
        $this->mRows = array();
        $this->mNumFields = sqlsrv_num_fields( $queryresult );
        $this->mFieldMeta = sqlsrv_field_metadata( $queryresult );

        $rows = sqlsrv_fetch_array( $queryresult, SQLSRV_FETCH_ASSOC );

        foreach ( $rows as $row ) {
            if ( $row !== null ) {
                foreach ( $row as $k => $v ) {
                    if ( is_object( $v ) && method_exists( $v, 'format' ) ) {// DateTime Object
                        $row[$k] = $v->format( "Y-m-d\TH:i:s\Z" );
                    }
                }
                $this->mRows[] = $row;// read results into memory, cursors are not supported
            }
        }
        $this->mRowCount = count( $this->mRows );
        sqlsrv_free_stmt( $queryresult );
    }

    private function array_to_obj( $array, &$obj ) {
        foreach ( $array as $key => $value ) {
            if ( is_array( $value ) ) {
                $obj->$key = new stdClass();
                $this->array_to_obj( $value, $obj->$key );
            } else {
                if ( !empty( $key ) ) {
                    $obj->$key = $value;
                }
            }
        }
        return $obj;
    }

    public function fetch( $mode = SQLSRV_FETCH_BOTH, $object_class = 'stdClass' ) {
        if ( $this->mCursor >= $this->mRowCount || $this->mRowCount == 0 ) {
            return false;
        }
        $arrNum = array();
        if ( $mode == SQLSRV_FETCH_NUMERIC || $mode == SQLSRV_FETCH_BOTH ) {
            foreach ( $this->mRows[$this->mCursor] as $value ) {
                $arrNum[] = $value;
            }
        }
        switch ( $mode ) {
            case SQLSRV_FETCH_ASSOC:
                $ret = $this->mRows[$this->mCursor];
                break;
            case SQLSRV_FETCH_NUMERIC:
                $ret = $arrNum;
                break;
            case 'OBJECT':
                $o = new $object_class;
                $ret = $this->array_to_obj( $this->mRows[$this->mCursor], $o );
                break;
            case SQLSRV_FETCH_BOTH:
            default:
                $ret = $this->mRows[$this->mCursor] + $arrNum;
                break;
        }

        $this->mCursor++;
        return $ret;
    }

    public function get( $pos, $fld ) {
        return $this->mRows[$pos][$fld];
    }

    public function numrows() {
        return $this->mRowCount;
    }

    public function seek( $iRow ) {
        $this->mCursor = min( $iRow, $this->mRowCount );
    }

    public function numfields() {
        return $this->mNumFields;
    }

    public function fieldname( $nr ) {
        $arrKeys = array_keys( $this->mRows[0] );
        return $arrKeys[$nr];
    }

    public function fieldtype( $nr ) {
        $i = 0;
        $intType = -1;
        foreach ( $this->mFieldMeta as $meta ) {
            if ( $nr == $i ) {
                $intType = $meta['Type'];
                break;
            }
            $i++;
        }
        // http://msdn.microsoft.com/en-us/library/cc296183.aspx contains type table
        switch ( $intType ) {
            case SQLSRV_SQLTYPE_BIGINT:
                $strType = 'bigint';
                break;
            case SQLSRV_SQLTYPE_BINARY:
                $strType = 'binary';
                break;
            case SQLSRV_SQLTYPE_BIT:
                $strType = 'bit';
                break;
            case SQLSRV_SQLTYPE_CHAR:
                $strType = 'char';
                break;
            case SQLSRV_SQLTYPE_DATETIME:
                $strType = 'datetime';
                break;
            case SQLSRV_SQLTYPE_DECIMAL: // ($precision, $scale)
                $strType = 'decimal';
                break;
            case SQLSRV_SQLTYPE_FLOAT:
                $strType = 'float';
                break;
            case SQLSRV_SQLTYPE_IMAGE:
                $strType = 'image';
                break;
            case SQLSRV_SQLTYPE_INT:
                $strType = 'int';
                break;
            case SQLSRV_SQLTYPE_MONEY:
                $strType = 'money';
                break;
            case SQLSRV_SQLTYPE_NCHAR: // ($charCount):
                $strType = 'nchar';
                break;
            case SQLSRV_SQLTYPE_NUMERIC: // ($precision, $scale):
                $strType = 'numeric';
                break;
            case SQLSRV_SQLTYPE_NVARCHAR: // ($charCount)
                $strType = 'nvarchar';
                break;
            // case SQLSRV_SQLTYPE_NVARCHAR('max'):
            //   $strType = 'nvarchar(MAX)';
            //   break;
            case SQLSRV_SQLTYPE_NTEXT:
                $strType = 'ntext';
                break;
            case SQLSRV_SQLTYPE_REAL:
                $strType = 'real';
                break;
            case SQLSRV_SQLTYPE_SMALLDATETIME:
                $strType = 'smalldatetime';
                break;
            case SQLSRV_SQLTYPE_SMALLINT:
                $strType = 'smallint';
                break;
            case SQLSRV_SQLTYPE_SMALLMONEY:
                $strType = 'smallmoney';
                break;
            case SQLSRV_SQLTYPE_TEXT:
                $strType = 'text';
                break;
            case SQLSRV_SQLTYPE_TIMESTAMP:
                $strType = 'timestamp';
                break;
            case SQLSRV_SQLTYPE_TINYINT:
                $strType = 'tinyint';
                break;
            case SQLSRV_SQLTYPE_UNIQUEIDENTIFIER:
                $strType = 'uniqueidentifier';
                break;
            case SQLSRV_SQLTYPE_UDT:
                $strType = 'UDT';
                break;
            case SQLSRV_SQLTYPE_VARBINARY: // ($byteCount)
                $strType = 'varbinary';
                break;
            // case SQLSRV_SQLTYPE_VARBINARY('max'):
            //   $strType = 'varbinary(MAX)';
            //   break;
            case SQLSRV_SQLTYPE_VARCHAR: // ($charCount)
                $strType = 'varchar';
                break;
            // case SQLSRV_SQLTYPE_VARCHAR('max'):
            //   $strType = 'varchar(MAX)';
            //   break;
            case SQLSRV_SQLTYPE_XML:
                $strType = 'xml';
                break;
            default:
                $strType = $intType;
        }
        return $strType;
    }

    public function free() {
        unset( $this->mRows );
    }
}