Set column comment when create table for mssql database

dialects/mssql.go

@@ -216,10 +216,12 @@ type mssql struct {
 	Base
 	defaultVarchar string
 	defaultChar    string
+	defaultSchema  string
 }
 
 func (db *mssql) Init(uri *URI) error {
 	db.quoter = mssqlQuoter
+	db.defaultSchema = "dbo"
 	return db.Base.Init(db, uri)
 }
 
@@ -249,10 +251,21 @@ func (db *mssql) SetParams(params map[string]string) {
 	} else {
 		db.defaultChar = "CHAR"
 	}
+
+	if defaultSchema, ok := params["DEFAULT_SCHEMA"]; ok && defaultSchema != "" {
+		db.defaultSchema = defaultSchema
+	} else {
+		db.defaultSchema = "dbo"
+	}
+
 }
 
 func (db *mssql) SQLType(c *schemas.Column) string {
 	var res string
+	var defaultVarchar string = schemas.Varchar
+	if db.defaultVarchar != "" {
+		defaultVarchar = db.defaultVarchar
+	}
 	switch t := c.SQLType.Name; t {
 	case schemas.Bool:
 		res = schemas.Bit
@@ -285,7 +298,7 @@ func (db *mssql) SQLType(c *schemas.Column) string {
 	case schemas.MediumInt:
 		res = schemas.Int
 	case schemas.Text, schemas.MediumText, schemas.TinyText, schemas.LongText, schemas.Json:
-		res = db.defaultVarchar + "(MAX)"
+		res = defaultVarchar + "(MAX)"
 	case schemas.Double:
 		res = schemas.Real
 	case schemas.Uuid:
@@ -303,7 +316,7 @@ func (db *mssql) SQLType(c *schemas.Column) string {
 			res += "(MAX)"
 		}
 	case schemas.Varchar:
-		res = db.defaultVarchar
+		res = defaultVarchar
 		if c.Length == -1 {
 			res += "(MAX)"
 		}
@@ -567,12 +580,23 @@ func (db *mssql) CreateTableSQL(table *schemas.Table, tableName string) ([]strin
 
 	pkList := table.PrimaryKeys
 
+	var multiCommentSql []string
+
 	for _, colName := range table.ColumnsSeq() {
 		col := table.GetColumn(colName)
 		s, _ := ColumnString(db, col, col.IsPrimaryKey && len(pkList) == 1)
 		sql += s
 		sql = strings.TrimSpace(sql)
 		sql += ", "
+
+		if col.Comment != "" {
+			commentSql := fmt.Sprintf("EXEC sys.sp_addextendedproperty @name=N'MS_Description', "+
+				"@value=N'%s' , "+
+				"@level0type=N'SCHEMA',@level0name=N'%s', "+
+				"@level1type=N'TABLE',@level1name=N'%s', "+
+				"@level2type=N'COLUMN',@level2name=N'%s'; ", col.Comment, db.defaultSchema, tableName, col.FieldName)
+			multiCommentSql = append(multiCommentSql, commentSql)
+		}
 	}
 
 	if len(pkList) > 1 {
@@ -583,7 +607,13 @@ func (db *mssql) CreateTableSQL(table *schemas.Table, tableName string) ([]strin
 
 	sql = sql[:len(sql)-2] + ")"
 	sql += ";"
-	return []string{sql}, true
+
+	multiSql := []string{sql}
+	if len(multiCommentSql) > 0 {
+		multiSql = append(multiSql, multiCommentSql...)
+	}
+
+	return multiSql, true
 }
 
 func (db *mssql) ForUpdateSQL(query string) string {