diff --git a/README.md b/README.md
index f895e12..e96107b 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/aldy505/bob.svg)](https://pkg.go.dev/github.com/aldy505/bob) [![Go Report Card](https://goreportcard.com/badge/github.com/aldy505/bob)](https://goreportcard.com/report/github.com/aldy505/bob) ![GitHub](https://img.shields.io/github/license/aldy505/bob) [![CodeFactor](https://www.codefactor.io/repository/github/aldy505/bob/badge)](https://www.codefactor.io/repository/github/aldy505/bob) [![codecov](https://codecov.io/gh/aldy505/bob/branch/master/graph/badge.svg?token=Noeexg5xEJ)](https://codecov.io/gh/aldy505/bob) [![Codacy Badge](https://app.codacy.com/project/badge/Grade/9b78970127c74c1a923533e05f65848d)](https://www.codacy.com/gh/aldy505/bob/dashboard?utm_source=github.com&utm_medium=referral&utm_content=aldy505/bob&utm_campaign=Badge_Grade) [![Build test](https://github.com/aldy505/bob/actions/workflows/build.yml/badge.svg)](https://github.com/aldy505/bob/actions/workflows/build.yml) [![Test and coverage](https://github.com/aldy505/bob/actions/workflows/coverage.yml/badge.svg)](https://github.com/aldy505/bob/actions/workflows/coverage.yml)
 
-Think of this as an extension of [Squirrel](https://github.com/Masterminds/squirrel) with functionability like [Knex](https://knexjs.org/). I still use Squirrel for other types of queries (insert, select, and all that), but I needed some SQL builder for create table and some other stuffs.
+Think of this as an extension of [Squirrel](https://github.com/Masterminds/squirrel) with functionability like [Knex](https://knexjs.org/). I still use Squirrel for other types of queries (insert, select, and all that), but I needed some SQL builder for create table and some other stuffs. Including database creation & upsert.
 
 Oh, and of course, heavily inspired by [Bob the Builder](https://en.wikipedia.org/wiki/Bob_the_Builder).
 
@@ -116,6 +116,44 @@ func main() {
 }
 ```
 
+### Upsert
+
+```go
+func main() {
+  sql, args, err := bob.
+    // Notice that you should give database dialect on the second params.
+    // Available database dialect are MySQL, PostgreSQL, SQLite, and MSSQL.
+    Upsert("users", bob.MySQL).
+    Columns("name", "email", "age").
+    // You could do multiple Values() call, but I'd suggest to not do it.
+    // Because this is an upsert function, not an insert one.
+    Values("Thomas Mueler", "tmueler@something.com", 25).
+    Replace("age", 25).
+    PlaceholderFormat(bob.Question).
+    ToSql()
+
+  // Another example for PostgreSQL
+  sql, args, err = bob.
+    Upsert("users", bob.PostgreSQL).
+    Columns("name", "email", "age").
+    Values("Billy Urtha", "billu@something.com", 30).
+    Key("email").
+    Replace("age", 40).
+    PlaceholderFormat(bob.Dollar).
+    ToSql()
+  
+  // One more time, for MSSQL / SQL Server.
+  sql, args, err = bob.
+    Upsert("users", bob.MSSQL).
+    Columns("name", "email", "age").
+    Values("George Rust", "georgee@something.com", 19).
+    Key("email", "georgee@something.com").
+    Replace("age", 18).
+    PlaceholderFormat(bob.AtP).
+    ToSql()
+}
+```
+
 ### Placeholder format / Dialect
 
 Default placeholder is a question mark (MySQL-like). If you want to change it, simply use something like this:
@@ -222,12 +260,12 @@ func main() {
 * `bob.DropTableIfExists(tableName)` - Drop a table if exists (`drop table if exists "users"`)
 * `bob.RenameTable(currentTable, desiredName)` - Rename a table (`rename table "users" to "people"`)
 * `bob.Truncate(tableName)` - Truncate a table (`truncate "users"`)
+* `bob.Upsert(tableName, dialect)` - UPSERT function (`insert into "users" ("name", "email") values (?, ?) on duplicate key update email = ?`)
 
 ### TODO
 
 Meaning these are some ideas for the future development of Bob.
 
-* `bob.Upsert(tableName)` - UPSERT function (`insert into "users" ("name", "email") values (?, ?) on duplicate key update email = ?`)
 * `bob.ExecWith()` - Just like Squirrel's [ExecWith](https://pkg.go.dev/github.com/Masterminds/squirrel?utm_source=godoc#ExecWith)
 * `bob.Count(tableName, columnName)` - Count query (`select count("active") from "users"`)
 
diff --git a/bob.go b/bob.go
index 57df6c6..a010263 100644
--- a/bob.go
+++ b/bob.go
@@ -14,10 +14,10 @@ var ErrEmptyTablePgx = errors.New("no rows in result set")
 var ErrDialectNotSupported = errors.New("provided database dialect is not supported")
 
 const (
-	Mysql int = iota
-	Postgresql
-	Sqlite
-	MSSql
+	MySQL int = iota
+	PostgreSQL
+	SQLite
+	MSSQL
 )
 
 // BobBuilderType is the type for BobBuilder
@@ -76,6 +76,23 @@ func (b BobBuilderType) Upsert(table string, dialect int) UpsertBuilder {
 var BobStmtBuilder = BobBuilderType(builder.EmptyBuilder)
 
 // CreateTable creates a table with CreateBuilder interface.
+// Refer to README for available column definition types.
+//
+//      // Note that CREATE TABLE doesn't returns args params.
+//      sql, _, err := bob.
+//        CreateTable("tableName").
+//        // The first parameter is the column's name.
+//        // The second parameters and so on forth are extras.
+//        StringColumn("id", "NOT NULL", "PRIMARY KEY", "AUTOINCREMENT").
+//        StringColumn("email", "NOT NULL", "UNIQUE").
+//        // See the list of available column definition types through pkg.go.dev or README.
+//        TextColumn("password").
+//        // Or add your custom type.
+//        AddColumn(bob.ColumnDef{Name: "tableName", Type: "customType", Extras: []string{"NOT NULL"}}).
+//        ToSql()
+//      if err != nil {
+//      // handle your error
+//      }
 func CreateTable(table string) CreateBuilder {
 	return BobStmtBuilder.CreateTable(table)
 }
@@ -117,6 +134,39 @@ func Truncate(table string) TruncateBuilder {
 
 // Upsert performs a UPSERT query with specified database dialect.
 // Supported database includes MySQL, PostgreSQL, SQLite and MSSQL.
+//
+//       // MySQL example:
+//       sql, args, err := bob.
+//         // Notice that you should give database dialect on the second params.
+//         // Available database dialect are MySQL, PostgreSQL, SQLite, and MSSQL.
+//         Upsert("users", bob.MySQL).
+//         Columns("name", "email", "age").
+//         // You could do multiple Values() call, but I'd suggest to not do it.
+//         // Because this is an upsert function, not an insert one.
+//         Values("Thomas Mueler", "tmueler@something.com", 25).
+//         Replace("age", 25).
+//         PlaceholderFormat(bob.Question).
+//         ToSql()
+//      
+//       // Another example for PostgreSQL:
+//       sql, args, err = bob.
+//         Upsert("users", bob.PostgreSQL).
+//         Columns("name", "email", "age").
+//         Values("Billy Urtha", "billu@something.com", 30).
+//         Key("email").
+//         Replace("age", 40).
+//         PlaceholderFormat(bob.Dollar).
+//         ToSql()
+//      
+//       // One more time, for MSSQL / SQL Server:
+//       sql, args, err = bob.
+//         Upsert("users", bob.MSSQL).
+//         Columns("name", "email", "age").
+//         Values("George Rust", "georgee@something.com", 19).
+//         Key("email", "georgee@something.com").
+//         Replace("age", 18).
+//         PlaceholderFormat(bob.AtP).
+//         ToSql()
 func Upsert(table string, dialect int) UpsertBuilder {
 	return BobStmtBuilder.Upsert(table, dialect)
 }
\ No newline at end of file
diff --git a/upsert.go b/upsert.go
index 5f3ef4b..43b3a43 100644
--- a/upsert.go
+++ b/upsert.go
@@ -100,7 +100,7 @@ func (d *upsertData) ToSql() (sqlStr string, args []interface{}, err error) {
 
 	sql := &bytes.Buffer{}
 
-	if d.Dialect == MSSql {
+	if d.Dialect == MSSQL {
 		if len(d.Key) == 0 {
 			err = errors.New("unique key and value must be provided for MS SQL")
 			return
@@ -145,12 +145,12 @@ func (d *upsertData) ToSql() (sqlStr string, args []interface{}, err error) {
 		replaces = append(replaces, replace)
 	}
 
-	if d.Dialect == Mysql {
+	if d.Dialect == MySQL {
 		// INSERT INTO table (col) VALUES (values) ON DUPLICATE KEY UPDATE col = value
 		
 		sql.WriteString("ON DUPLICATE KEY UPDATE ")
 		sql.WriteString(strings.Join(replaces, ", "))
-	} else if d.Dialect == Postgresql || d.Dialect == Sqlite {
+	} else if d.Dialect == PostgreSQL || d.Dialect == SQLite {
 		// INSERT INTO players (user_name, age) VALUES('steven', 32) ON CONFLICT(user_name) DO UPDATE SET age=excluded.age;
 		
 		if len(d.Key) == 0 {
@@ -163,7 +163,7 @@ func (d *upsertData) ToSql() (sqlStr string, args []interface{}, err error) {
 		sql.WriteString("DO UPDATE SET ")
 		sql.WriteString(strings.Join(replaces, ", "))
 
-	} else if d.Dialect == MSSql {
+	} else if d.Dialect == MSSQL {
 		// IF NOT EXISTS (SELECT * FROM dbo.Table1 WHERE ID = @ID)
     //    INSERT INTO dbo.Table1(ID, Name, ItemName, ItemCatName, ItemQty)
     //    VALUES(@ID, @Name, @ItemName, @ItemCatName, @ItemQty)
diff --git a/upsert_test.go b/upsert_test.go
index ab4f8a5..925b20f 100644
--- a/upsert_test.go
+++ b/upsert_test.go
@@ -10,7 +10,7 @@ import (
 func TestUpsert(t *testing.T) {
 	t.Run("should be able to generate upsert query for mysql", func(t *testing.T) {
 		sql, args, err := bob.
-			Upsert("users", bob.Mysql).
+			Upsert("users", bob.MySQL).
 			Columns("name", "email").
 			Values("John Doe", "john@doe.com").
 			Replace("name", "John Does").
@@ -32,7 +32,7 @@ func TestUpsert(t *testing.T) {
 
 	t.Run("should be able to generate upsert query for postgres", func(t *testing.T) {
 		sql, args, err := bob.
-			Upsert("users", bob.Postgresql).
+			Upsert("users", bob.PostgreSQL).
 			Columns("name", "email").
 			Values("John Doe", "john@doe.com").
 			Key("email").
@@ -56,7 +56,7 @@ func TestUpsert(t *testing.T) {
 
 	t.Run("should be able to generate upsert query for sqlite", func(t *testing.T) {
 		sql, args, err := bob.
-			Upsert("users", bob.Sqlite).
+			Upsert("users", bob.SQLite).
 			Columns("name", "email").
 			Values("John Doe", "john@doe.com").
 			Key("email").
@@ -80,7 +80,7 @@ func TestUpsert(t *testing.T) {
 
 	t.Run("should be able to generate upsert query for mssql", func(t *testing.T) {
 		sql, args, err := bob.
-			Upsert("users", bob.MSSql).
+			Upsert("users", bob.MSSQL).
 			Columns("name", "email").
 			Values("John Doe", "john@doe.com").
 			Key("email", "john@doe.com").
@@ -103,42 +103,42 @@ func TestUpsert(t *testing.T) {
 	})
 
 	t.Run("should emit error without table name", func(t *testing.T) {
-		_, _, err := bob.Upsert("", bob.Mysql).ToSql()
+		_, _, err := bob.Upsert("", bob.MySQL).ToSql()
 		if err == nil && err.Error() != "upsert statement must specify a table" {
 			t.Error(err)
 		}
 	})
 
 	t.Run("should emit error without columns", func(t *testing.T) {
-		_, _, err := bob.Upsert("users", bob.Postgresql).ToSql()
+		_, _, err := bob.Upsert("users", bob.PostgreSQL).ToSql()
 		if err.Error() != "upsert statement must have at least one column" {
 			t.Error(err)
 		}
 	})
 
 	t.Run("should emit error without values", func(t *testing.T) {
-		_, _, err := bob.Upsert("users", bob.Postgresql).Columns("name", "email").ToSql()
+		_, _, err := bob.Upsert("users", bob.PostgreSQL).Columns("name", "email").ToSql()
 		if err.Error() != "upsert statements must have at least one set of values" {
 			t.Error(err)
 		}
 	})
 
 	t.Run("should emit error without replaces", func(t *testing.T) {
-		_, _, err := bob.Upsert("users", bob.Postgresql).Columns("name", "email").Values("James", "james@mail.com").ToSql()
+		_, _, err := bob.Upsert("users", bob.PostgreSQL).Columns("name", "email").Values("James", "james@mail.com").ToSql()
 		if err.Error() != "upsert statement must have at least one key value pair to be replaced" {
 			t.Error(err)
 		}
 	})
 
 	t.Run("should emit error without key and value for mssql", func(t *testing.T) {
-		_, _, err := bob.Upsert("users", bob.MSSql).Columns("name", "email").Values("James", "james@mail.com").Replace("name", "Thomas").ToSql()
+		_, _, err := bob.Upsert("users", bob.MSSQL).Columns("name", "email").Values("James", "james@mail.com").Replace("name", "Thomas").ToSql()
 		if err.Error() != "unique key and value must be provided for MS SQL" {
 			t.Error(err)
 		}
 	})
 
 	t.Run("should emit error without key and value for mssql", func(t *testing.T) {
-		_, _, err := bob.Upsert("users", bob.Sqlite).Columns("name", "email").Values("James", "james@mail.com").Replace("name", "Thomas").ToSql()
+		_, _, err := bob.Upsert("users", bob.SQLite).Columns("name", "email").Values("James", "james@mail.com").Replace("name", "Thomas").ToSql()
 		if err.Error() != "unique key must be provided for PostgreSQL and SQLite" {
 			t.Log(err.Error())
 			t.Error(err)