Update .net core project

Src/Asp.NetCore2/SqlSugar.MySqlConnectorCore/MySql/DbMaintenance/MySqlDbMaintenance.cs

@@ -454,10 +454,10 @@ namespace SqlSugar.MySqlConnector
             }
             if (defaultValue.ToLower().IsIn("now()", "current_timestamp") || defaultValue.ToLower().Contains("current_timestamp"))
             {
-                string template = "ALTER table {0} CHANGE COLUMN {1} {1} {3} default {2}";
+                string template = "ALTER table {0} CHANGE COLUMN {1} {1} {3} {4} default {2} COMMENT '{5}'";
                 var dbColumnInfo = this.Context.DbMaintenance.GetColumnInfosByTableName(tableName).First(it => it.DbColumnName.Equals(columnName, StringComparison.CurrentCultureIgnoreCase));
                 var value = Regex.Match(defaultValue, @"\(\d\)$").Value;
-                string sql = string.Format(template, tableName, columnName, defaultValue, dbColumnInfo.DataType+ value);
+                string sql = string.Format(template, tableName, columnName, defaultValue, dbColumnInfo.DataType + value, dbColumnInfo.IsNullable ? " NULL " : " NOT NULL ", dbColumnInfo.ColumnDescription);
                 this.Context.Ado.ExecuteCommand(sql);
                 return true;
             }

Src/Asp.NetCore2/SqlSugar/Realization/MySql/DbMaintenance/MySqlDbMaintenance.cs

@@ -456,10 +456,10 @@ namespace SqlSugar
             }
             if (defaultValue.ToLower().IsIn("now()", "current_timestamp") || defaultValue.ToLower().Contains("current_timestamp"))
             {
-                string template = "ALTER table {0} CHANGE COLUMN {1} {1} {3} default {2}";
+                string template = "ALTER table {0} CHANGE COLUMN {1} {1} {3} {4} default {2} COMMENT '{5}'";
                 var dbColumnInfo = this.Context.DbMaintenance.GetColumnInfosByTableName(tableName).First(it => it.DbColumnName.Equals(columnName, StringComparison.CurrentCultureIgnoreCase));
                 var value = Regex.Match(defaultValue, @"\(\d\)$").Value;
-                string sql = string.Format(template, tableName, columnName, defaultValue, dbColumnInfo.DataType+ value);
+                string sql = string.Format(template, tableName, columnName, defaultValue, dbColumnInfo.DataType + value, dbColumnInfo.IsNullable ? " NULL " : " NOT NULL ", dbColumnInfo.ColumnDescription);
                 this.Context.Ado.ExecuteCommand(sql);
                 return true;
             }