diff --git a/framework/db/ColumnSchemaBuilder.php b/framework/db/ColumnSchemaBuilder.php
index edb28ef..cb0e849 100644
--- a/framework/db/ColumnSchemaBuilder.php
+++ b/framework/db/ColumnSchemaBuilder.php
@@ -331,35 +331,46 @@ class ColumnSchemaBuilder extends BaseObject
     }
 
     /**
-     * Builds the default value specification for the column.
-     * @return string string with default value of column.
+     * Return the default value for the column.
+     * @return string|null string with default value of column.
      */
-    protected function buildDefaultString()
+    protected function buildDefaultValue()
     {
         if ($this->default === null) {
-            return $this->isNotNull === false ? ' DEFAULT NULL' : '';
+            return $this->isNotNull === false ? 'NULL' : null;
         }
 
-        $string = ' DEFAULT ';
         switch (gettype($this->default)) {
-            case 'integer':
-                $string .= (string) $this->default;
-                break;
             case 'double':
                 // ensure type cast always has . as decimal separator in all locales
-                $string .= StringHelper::floatToString($this->default);
+                $defaultValue = StringHelper::floatToString($this->default);
                 break;
             case 'boolean':
-                $string .= $this->default ? 'TRUE' : 'FALSE';
+                $defaultValue = $this->default ? 'TRUE' : 'FALSE';
                 break;
+            case 'integer':
             case 'object':
-                $string .= (string) $this->default;
+                $defaultValue = (string) $this->default;
                 break;
             default:
-                $string .= "'{$this->default}'";
+                $defaultValue = "'{$this->default}'";
+        }
+
+        return $defaultValue;
+    }
+
+    /**
+     * Builds the default value specification for the column.
+     * @return string string with default value of column.
+     */
+    protected function buildDefaultString()
+    {
+        $defaultValue = $this->buildDefaultValue();
+        if ($defaultValue === null) {
+            return '';
         }
 
-        return $string;
+        return ' DEFAULT ' . $defaultValue;
     }
 
     /**
diff --git a/framework/db/mssql/ColumnSchemaBuilder.php b/framework/db/mssql/ColumnSchemaBuilder.php
new file mode 100644
index 0000000..c6f8f54
--- /dev/null
+++ b/framework/db/mssql/ColumnSchemaBuilder.php
@@ -0,0 +1,77 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\db\mssql;
+
+use yii\db\ColumnSchemaBuilder as AbstractColumnSchemaBuilder;
+use yii\db\Expression;
+
+/**
+ * ColumnSchemaBuilder is the schema builder for MySQL databases.
+ *
+ * @author Chris Harris <chris@buckshotsoftware.com>
+ * @since 2.0.8
+ */
+class ColumnSchemaBuilder extends AbstractColumnSchemaBuilder
+{
+    protected $format = '{type}{length}{notnull}{unique}{default}{check}{append}';
+
+    /**
+     * Builds the full string for the column's schema.
+     * @return string
+     */
+    public function __toString()
+    {
+        switch ($this->getTypeCategory()) {
+            case self::CATEGORY_PK:
+                $format = '{type}{check}{comment}{append}';
+                break;
+            default:
+                $format = $this->format;
+        }
+
+        return $this->buildCompleteString($format);
+    }
+
+    /**
+     * Changes default format string for MSSQL ALTER COMMAND
+     */
+    public function isAlterColumn()
+    {
+        $this->format = '{type}{length}{notnull}{append}';
+    }
+
+    /**
+     * Getting the `Default` value for constraint
+     * @return string|Expression|null
+     */
+    public function getDefaultValue()
+    {
+        if ($this->default instanceof Expression) {
+            return $this->default;
+        }
+
+        return $this->buildDefaultValue();
+    }
+
+    /**
+     * Get the `Check` value for constraint
+     * @return string|null
+     */
+    public function getCheckValue()
+    {
+        return $this->check !== null ? "{$this->check}" : null;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isUnique()
+    {
+        return $this->isUnique;
+    }
+}
diff --git a/framework/db/mssql/QueryBuilder.php b/framework/db/mssql/QueryBuilder.php
index 66e169c..ddf752d 100644
--- a/framework/db/mssql/QueryBuilder.php
+++ b/framework/db/mssql/QueryBuilder.php
@@ -174,32 +174,28 @@ class QueryBuilder extends \yii\db\QueryBuilder
      */
     public function alterColumn($table, $column, $type)
     {
-        $sqlAfter = [];
+        $sqlAfter[] = $this->dropConstraintsForColumn($table, $column, 'D');
 
-        $columnName = $this->db->quoteColumnName($column);
-        $tableName = $this->db->quoteTableName($table);
+        if ($type instanceof \yii\db\mssql\ColumnSchemaBuilder) {
+            $type->isAlterColumn();
 
-        $constraintBase = preg_replace('/[^a-z0-9_]/i', '', $table . '_' . $column);
+            $columnName = $this->db->quoteColumnName($column);
+            $tableName = $this->db->quoteTableName($table);
+            $constraintBase = preg_replace('/[^a-z0-9_]/i', '', $table . '_' . $column);
 
-        $type = $this->getColumnType($type);
-
-        if (preg_match('/\s+DEFAULT\s+(["\']?\w*["\']?)/i', $type, $matches)) {
-            $value = strtolower($matches[1]) === 'null' ? null : $matches[1];
-            $type = preg_replace('/\s+DEFAULT\s+(["\']?\w*["\']?)/i', '', $type);
-            $sqlAfter[] = $this->dropConstraintsForColumn($table, $column, 'D');
-            $sqlAfter[] = $this->addDefaultValue("DF_{$constraintBase}", $table, $column, $value);
-        } else {
-            $sqlAfter[] = $this->dropConstraintsForColumn($table, $column, 'D');
-        }
+            $defaultValue = $type->getDefaultValue();
+            if ($defaultValue !== null) {
+                $sqlAfter[] = $this->addDefaultValue("DF_{$constraintBase}", $table, $column, $defaultValue instanceof Expression ?  $defaultValue : new Expression($defaultValue));
+            }
 
-        if (preg_match('/\s+CHECK\s+\((.+)\)/i', $type, $matches)) {
-            $type = preg_replace('/\s+CHECK\s+\((.+)\)/i', '', $type);
-            $sqlAfter[] = "ALTER TABLE {$tableName} ADD CONSTRAINT " . $this->db->quoteColumnName("CK_{$constraintBase}") . " CHECK ({$matches[1]})";
-        }
+            $checkValue = $type->getCheckValue();
+            if ($checkValue !== null) {
+                $sqlAfter[] = "ALTER TABLE {$tableName} ADD CONSTRAINT " . $this->db->quoteColumnName("CK_{$constraintBase}") . " CHECK ({$checkValue})";
+            }
 
-        $type = preg_replace('/\s+UNIQUE/i', '', $type, -1, $count);
-        if ($count) {
-            $sqlAfter[] = "ALTER TABLE {$tableName} ADD CONSTRAINT " . $this->db->quoteColumnName("UQ_{$constraintBase}") . " UNIQUE ({$columnName})";
+            if ($type->isUnique()) {
+                $sqlAfter[] = "ALTER TABLE {$tableName} ADD CONSTRAINT " . $this->db->quoteColumnName("UQ_{$constraintBase}") . " UNIQUE ({$columnName})";
+            }
         }
 
         return 'ALTER TABLE ' . $this->db->quoteTableName($table) . ' ALTER COLUMN '
@@ -214,7 +210,7 @@ class QueryBuilder extends \yii\db\QueryBuilder
     public function addDefaultValue($name, $table, $column, $value)
     {
         return 'ALTER TABLE ' . $this->db->quoteTableName($table) . ' ADD CONSTRAINT '
-            . $this->db->quoteColumnName($name) . ' DEFAULT ' . ($value === null ? 'NULL' : $this->db->quoteValue($value)) . ' FOR '
+            . $this->db->quoteColumnName($name) . ' DEFAULT ' . $this->db->quoteValue($value) . ' FOR '
             . $this->db->quoteColumnName($column);
     }
 
@@ -662,5 +658,4 @@ END";
         return $this->dropConstraintsForColumn($table, $column) . "\nALTER TABLE " . $this->db->quoteTableName($table)
             . " DROP COLUMN " . $this->db->quoteColumnName($column);
     }
-
 }
diff --git a/framework/db/mssql/Schema.php b/framework/db/mssql/Schema.php
index 365d96e..a2ad449 100644
--- a/framework/db/mssql/Schema.php
+++ b/framework/db/mssql/Schema.php
@@ -804,4 +804,12 @@ SQL;
 
         return $result;
     }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function createColumnSchemaBuilder($type, $length = null)
+    {
+        return new ColumnSchemaBuilder($type, $length, $this->db);
+    }
 }
diff --git a/tests/framework/db/mssql/QueryBuilderTest.php b/tests/framework/db/mssql/QueryBuilderTest.php
index df16edc..3a17357 100644
--- a/tests/framework/db/mssql/QueryBuilderTest.php
+++ b/tests/framework/db/mssql/QueryBuilderTest.php
@@ -552,7 +552,7 @@ WHILE 1=1 BEGIN
     IF @constraintName IS NULL BREAK
     EXEC (N'ALTER TABLE ' + @tableName + ' DROP CONSTRAINT [' + @constraintName + ']')
 END
-ALTER TABLE [foo1] ADD CONSTRAINT [DF_foo1_bar] DEFAULT '''''' FOR [bar]";
+ALTER TABLE [foo1] ADD CONSTRAINT [DF_foo1_bar] DEFAULT '' FOR [bar]";
         $sql = $qb->alterColumn('foo1', 'bar', $this->string(255)->defaultValue(''));
         $this->assertEquals($expected, $sql);
 
@@ -579,7 +579,7 @@ WHILE 1=1 BEGIN
     IF @constraintName IS NULL BREAK
     EXEC (N'ALTER TABLE ' + @tableName + ' DROP CONSTRAINT [' + @constraintName + ']')
 END
-ALTER TABLE [foo1] ADD CONSTRAINT [DF_foo1_bar] DEFAULT '''AbCdE''' FOR [bar]";
+ALTER TABLE [foo1] ADD CONSTRAINT [DF_foo1_bar] DEFAULT 'AbCdE' FOR [bar]";
         $sql = $qb->alterColumn('foo1', 'bar', $this->string(255)->defaultValue('AbCdE'));
         $this->assertEquals($expected, $sql);
 
@@ -606,7 +606,7 @@ WHILE 1=1 BEGIN
     IF @constraintName IS NULL BREAK
     EXEC (N'ALTER TABLE ' + @tableName + ' DROP CONSTRAINT [' + @constraintName + ']')
 END
-ALTER TABLE [foo1] ADD CONSTRAINT [DF_foo1_bar] DEFAULT 'CURRENT_TIMESTAMP' FOR [bar]";
+ALTER TABLE [foo1] ADD CONSTRAINT [DF_foo1_bar] DEFAULT CURRENT_TIMESTAMP FOR [bar]";
         $sql = $qb->alterColumn('foo1', 'bar', $this->timestamp()->defaultExpression('CURRENT_TIMESTAMP'));
         $this->assertEquals($expected, $sql);
 
@@ -688,6 +688,38 @@ ALTER TABLE [foo1] ADD CONSTRAINT [DF_foo1_bar] DEFAULT NULL FOR [bar]";
         $this->assertEquals($expected, $sql);
     }
 
+    public function testAlterColumnWithExpression()
+    {
+        $qb = $this->getQueryBuilder();
+
+        $expected = "ALTER TABLE [foo1] ALTER COLUMN [bar] int NULL
+DECLARE @tableName VARCHAR(MAX) = '[foo1]'
+DECLARE @columnName VARCHAR(MAX) = 'bar'
+
+WHILE 1=1 BEGIN
+    DECLARE @constraintName NVARCHAR(128)
+    SET @constraintName = (SELECT TOP 1 OBJECT_NAME(cons.[object_id])
+        FROM (
+            SELECT sc.[constid] object_id
+            FROM [sys].[sysconstraints] sc
+            JOIN [sys].[columns] c ON c.[object_id]=sc.[id] AND c.[column_id]=sc.[colid] AND c.[name]=@columnName
+            WHERE sc.[id] = OBJECT_ID(@tableName)
+            UNION
+            SELECT object_id(i.[name]) FROM [sys].[indexes] i
+            JOIN [sys].[columns] c ON c.[object_id]=i.[object_id] AND c.[name]=@columnName
+            JOIN [sys].[index_columns] ic ON ic.[object_id]=i.[object_id] AND i.[index_id]=ic.[index_id] AND c.[column_id]=ic.[column_id]
+            WHERE i.[is_unique_constraint]=1 and i.[object_id]=OBJECT_ID(@tableName)
+        ) cons
+        JOIN [sys].[objects] so ON so.[object_id]=cons.[object_id]
+         WHERE so.[type]='D')
+    IF @constraintName IS NULL BREAK
+    EXEC (N'ALTER TABLE ' + @tableName + ' DROP CONSTRAINT [' + @constraintName + ']')
+END
+ALTER TABLE [foo1] ADD CONSTRAINT [DF_foo1_bar] DEFAULT CAST(GETDATE() AS INT) FOR [bar]";
+        $sql = $qb->alterColumn('foo1', 'bar', $this->integer()->null()->defaultValue(new Expression('CAST(GETDATE() AS INT)')));
+        $this->assertEquals($expected, $sql);
+    }
+
     public function testAlterColumnWithCheckConstraintOnDb()
     {
         $connection = $this->getConnection();