diff --git a/builder/table.go b/builder/table.go
index 1777451..27713d0 100644
--- a/builder/table.go
+++ b/builder/table.go
@@ -7,8 +7,10 @@ import (
 	"github.com/go-rel/rel"
 )
 
-type ColumnMapper func(*rel.Column) (string, int, int)
-type DefinitionFilter func(table rel.Table, def rel.TableDefinition) bool
+type (
+	ColumnMapper     func(*rel.Column) (string, int, int)
+	DefinitionFilter func(table rel.Table, def rel.TableDefinition) bool
+)
 
 // Table builder.
 type Table struct {
@@ -19,9 +21,7 @@ type Table struct {
 
 // Build SQL query for table creation and modification.
 func (t Table) Build(table rel.Table) string {
-	var (
-		buffer = t.BufferFactory.Create()
-	)
+	buffer := t.BufferFactory.Create()
 
 	switch table.Op {
 	case rel.SchemaCreate:
@@ -86,6 +86,10 @@ func (t Table) WriteAlterTable(buffer *Buffer, table rel.Table) {
 			case rel.SchemaCreate:
 				buffer.WriteString("ADD COLUMN ")
 				t.WriteColumn(buffer, v)
+			case rel.SchemaAlter:
+				buffer.WriteString("ALTER COLUMN ")
+				buffer.WriteEscape(v.Name)
+				t.WriteAlterColumn(buffer, v)
 			case rel.SchemaRename:
 				// Add Change
 				buffer.WriteString("RENAME COLUMN ")
@@ -131,14 +135,10 @@ func (t Table) WriteDropTable(buffer *Buffer, table rel.Table) {
 	buffer.WriteByte(';')
 }
 
-// WriteColumn definition to buffer.
-func (t Table) WriteColumn(buffer *Buffer, column rel.Column) {
-	var (
-		typ, m, n = t.ColumnMapper(&column)
-	)
+// WriteColumnType definition to buffer.
+func (t Table) WriteColumnType(buffer *Buffer, column rel.Column) {
+	typ, m, n := t.ColumnMapper(&column)
 
-	buffer.WriteEscape(column.Name)
-	buffer.WriteByte(' ')
 	buffer.WriteString(typ)
 
 	if m != 0 {
@@ -156,6 +156,14 @@ func (t Table) WriteColumn(buffer *Buffer, column rel.Column) {
 	if column.Unsigned {
 		buffer.WriteString(" UNSIGNED")
 	}
+}
+
+// WriteColumn definition to buffer.
+func (t Table) WriteColumn(buffer *Buffer, column rel.Column) {
+	buffer.WriteEscape(column.Name)
+	buffer.WriteByte(' ')
+
+	t.WriteColumnType(buffer, column)
 
 	if column.Unique {
 		buffer.WriteString(" UNIQUE")
@@ -177,11 +185,31 @@ func (t Table) WriteColumn(buffer *Buffer, column rel.Column) {
 	t.WriteOptions(buffer, column.Options)
 }
 
+// WriteAlterColumn definition to buffer.
+func (t Table) WriteAlterColumn(buffer *Buffer, column rel.Column) {
+	switch column.Constr {
+	case rel.AlterColumnType:
+		buffer.WriteString(" TYPE ")
+		t.WriteColumnType(buffer, column)
+	case rel.AlterColumnDefault:
+		if column.Default != nil {
+			buffer.WriteString(" SET DEFAULT ")
+			buffer.WriteValue(column.Default)
+		} else {
+			buffer.WriteString(" DROP DEFAULT")
+		}
+	case rel.AlterColumnRequired:
+		if column.Required {
+			buffer.WriteString(" SET NOT NULL")
+		} else {
+			buffer.WriteString(" DROP NOT NULL")
+		}
+	}
+}
+
 // WriteKey definition to buffer.
 func (t Table) WriteKey(buffer *Buffer, key rel.Key) {
-	var (
-		typ = string(key.Type)
-	)
+	typ := string(key.Type)
 
 	buffer.WriteString(typ)
 
diff --git a/builder/table_test.go b/builder/table_test.go
index 2cbf657..73c06b4 100644
--- a/builder/table_test.go
+++ b/builder/table_test.go
@@ -10,12 +10,10 @@ import (
 )
 
 func TestTable_Build(t *testing.T) {
-	var (
-		tableBuilder = Table{
-			BufferFactory: BufferFactory{InlineValues: true, BoolTrueValue: "true", BoolFalseValue: "false", Quoter: Quote{IDPrefix: "`", IDSuffix: "`", IDSuffixEscapeChar: "`", ValueQuote: "'", ValueQuoteEscapeChar: "'"}},
-			ColumnMapper:  sql.ColumnMapper,
-		}
-	)
+	tableBuilder := Table{
+		BufferFactory: BufferFactory{InlineValues: true, BoolTrueValue: "true", BoolFalseValue: "false", Quoter: Quote{IDPrefix: "`", IDSuffix: "`", IDSuffixEscapeChar: "`", ValueQuote: "'", ValueQuoteEscapeChar: "'"}},
+		ColumnMapper:  sql.ColumnMapper,
+	}
 
 	tests := []struct {
 		result string
@@ -80,14 +78,13 @@ func TestTable_Build(t *testing.T) {
 			},
 		},
 		{
-			result: "ALTER TABLE `columns` ADD COLUMN `verified` BOOL;ALTER TABLE `columns` RENAME COLUMN `string` TO `name`;ALTER TABLE `columns` ;ALTER TABLE `columns` DROP COLUMN `blob`;",
+			result: "ALTER TABLE `columns` ADD COLUMN `verified` BOOL;ALTER TABLE `columns` RENAME COLUMN `string` TO `name`;ALTER TABLE `columns` DROP COLUMN `blob`;",
 			table: rel.Table{
 				Op:   rel.SchemaAlter,
 				Name: "columns",
 				Definitions: []rel.TableDefinition{
 					rel.Column{Name: "verified", Type: rel.Bool, Op: rel.SchemaCreate},
 					rel.Column{Name: "string", Rename: "name", Op: rel.SchemaRename},
-					rel.Column{Name: "bool", Type: rel.Int, Op: rel.SchemaAlter},
 					rel.Column{Name: "blob", Op: rel.SchemaDrop},
 				},
 			},
@@ -102,6 +99,29 @@ func TestTable_Build(t *testing.T) {
 				},
 			},
 		},
+		{
+			result: "ALTER TABLE `columns` ALTER COLUMN `name` TYPE VARCHAR(100);",
+			table: rel.Table{
+				Op:   rel.SchemaAlter,
+				Name: "columns",
+				Definitions: []rel.TableDefinition{
+					rel.Column{Name: "name", Type: rel.String, Limit: 100, Op: rel.SchemaAlter, Constr: rel.AlterColumnType},
+				},
+			},
+		},
+		{
+			result: "ALTER TABLE `columns` ALTER COLUMN `bool` SET DEFAULT 1;ALTER TABLE `columns` ALTER COLUMN `bool` SET NOT NULL;ALTER TABLE `columns` ALTER COLUMN `verified` DROP DEFAULT;ALTER TABLE `columns` ALTER COLUMN `verified` DROP NOT NULL;",
+			table: rel.Table{
+				Op:   rel.SchemaAlter,
+				Name: "columns",
+				Definitions: []rel.TableDefinition{
+					rel.Column{Name: "bool", Default: 1, Op: rel.SchemaAlter, Constr: rel.AlterColumnDefault},
+					rel.Column{Name: "bool", Required: true, Op: rel.SchemaAlter, Constr: rel.AlterColumnRequired},
+					rel.Column{Name: "verified", Default: nil, Op: rel.SchemaAlter, Constr: rel.AlterColumnDefault},
+					rel.Column{Name: "verified", Op: rel.SchemaAlter, Constr: rel.AlterColumnRequired},
+				},
+			},
+		},
 		{
 			result: "ALTER TABLE `table` RENAME TO `table1`;",
 			table: rel.Table{
@@ -143,6 +163,11 @@ func TestTable_BuildWithDefinitionFilter(t *testing.T) {
 			if ok && table.Op == rel.SchemaAlter {
 				return false
 			}
+			// > Other kinds of ALTER TABLE operations such as ALTER COLUMN, ADD CONSTRAINT, and so forth are omitted.
+			col, ok := def.(rel.Column)
+			if ok && col.Op == rel.SchemaAlter {
+				return false
+			}
 
 			return true
 		}
@@ -182,18 +207,40 @@ func TestTable_BuildWithDefinitionFilter(t *testing.T) {
 			},
 		},
 		{
-			result: "ALTER TABLE `columns` ADD COLUMN `verified` BOOL;ALTER TABLE `columns` RENAME COLUMN `string` TO `name`;ALTER TABLE `columns` ;ALTER TABLE `columns` DROP COLUMN `blob`;",
+			result: "ALTER TABLE `columns` ADD COLUMN `verified` BOOL;ALTER TABLE `columns` RENAME COLUMN `string` TO `name`;ALTER TABLE `columns` DROP COLUMN `blob`;",
 			table: rel.Table{
 				Op:   rel.SchemaAlter,
 				Name: "columns",
 				Definitions: []rel.TableDefinition{
 					rel.Column{Name: "verified", Type: rel.Bool, Op: rel.SchemaCreate},
 					rel.Column{Name: "string", Rename: "name", Op: rel.SchemaRename},
-					rel.Column{Name: "bool", Type: rel.Int, Op: rel.SchemaAlter},
 					rel.Column{Name: "blob", Op: rel.SchemaDrop},
 				},
 			},
 		},
+		{
+			result: "",
+			table: rel.Table{
+				Op:   rel.SchemaAlter,
+				Name: "columns",
+				Definitions: []rel.TableDefinition{
+					rel.Column{Name: "name", Type: rel.String, Limit: 100, Op: rel.SchemaAlter, Constr: rel.AlterColumnType},
+				},
+			},
+		},
+		{
+			result: "",
+			table: rel.Table{
+				Op:   rel.SchemaAlter,
+				Name: "columns",
+				Definitions: []rel.TableDefinition{
+					rel.Column{Name: "bool", Default: 1, Op: rel.SchemaAlter, Constr: rel.AlterColumnDefault},
+					rel.Column{Name: "bool", Required: true, Op: rel.SchemaAlter, Constr: rel.AlterColumnRequired},
+					rel.Column{Name: "verified", Default: nil, Op: rel.SchemaAlter, Constr: rel.AlterColumnDefault},
+					rel.Column{Name: "verified", Op: rel.SchemaAlter, Constr: rel.AlterColumnRequired},
+				},
+			},
+		},
 		{
 			result: "",
 			table: rel.Table{
diff --git a/go.mod b/go.mod
index 6bc4400..38b74f7 100644
--- a/go.mod
+++ b/go.mod
@@ -19,3 +19,5 @@ require (
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
+
+replace github.com/go-rel/rel v0.39.0 => github.com/lafriks-fork/rel v0.39.1-0.20221108214643-1b07f1a5dddc
diff --git a/go.sum b/go.sum
index 307a430..1ec33bb 100644
--- a/go.sum
+++ b/go.sum
@@ -4,10 +4,10 @@ github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
 github.com/fsnotify/fsnotify v1.6.0 h1:n+5WquG0fcWoWp6xPWfHdbskMCQaFnG6PfBrh1Ky4HY=
 github.com/fsnotify/fsnotify v1.6.0/go.mod h1:sl3t1tCWJFWoRz9R8WJCbQihKKwmorjAbSClcnxKAGw=
-github.com/go-rel/rel v0.39.0 h1:2zmK8kazM82iRRfWX7+mm1MxDkGKDj2W+xJLjguli5U=
-github.com/go-rel/rel v0.39.0/go.mod h1:yN6+aimHyRIzbuWFe5DaxiZPuVuPfd7GlLpy/YTqTUg=
 github.com/jinzhu/inflection v1.0.0 h1:K317FqzuhWc8YvSVlFMCCUb36O/S9MCKRDI7QkRKD/E=
 github.com/jinzhu/inflection v1.0.0/go.mod h1:h+uFLlag+Qp1Va5pdKtLDYj+kHp5pxUVkryuEj+Srlc=
+github.com/lafriks-fork/rel v0.39.1-0.20221108214643-1b07f1a5dddc h1:DfFCMkOmGZw67NjY95zYLNLt13kW+P5+nM8pQUKR4c8=
+github.com/lafriks-fork/rel v0.39.1-0.20221108214643-1b07f1a5dddc/go.mod h1:ZmXMIRDQHbw29qOfWtO6HSq1UqNxthlsjmt++3FZSDs=
 github.com/nxadm/tail v1.4.8 h1:nPr65rt6Y5JFSKQO7qToXr7pePgD6Gwiw05lkbyAQTE=
 github.com/nxadm/tail v1.4.8/go.mod h1:+ncqLTQzXmGhMZNUePPaPqPvBxHAIsmXswZKocGu+AU=
 github.com/onsi/ginkgo v1.15.0 h1:1V1NfVQR87RtWAgp1lv9JZJ5Jap+XFGKPi00andXGi4=