PgSql CodeFirst alter column bug

Src/Asp.Net/PgSqlTest/UnitTest/Main.cs

@@ -38,9 +38,9 @@ namespace OrmTest
             Ado();
             Queryable();
             QueryableAsync();
-            Thread();
+            //Thread();
-            Thread2();
+            //Thread2();
-            Thread3();
+            //Thread3();
         }
     }
 }

Src/Asp.Net/PgSqlTest/UnitTest/UCodeFirst.cs

@@ -13,7 +13,24 @@ namespace OrmTest
             if (Db.DbMaintenance.IsAnyTable("UnitCodeTest1", false))
                 Db.DbMaintenance.DropTable("UnitCodeTest1");
             Db.CodeFirst.InitTables<UnitCodeTest1>();
+            Db.CodeFirst.InitTables<UnitCodeTest22>();
+            Db.Insertable(new UnitCodeTest22()).ExecuteCommand();
+            Db.DbMaintenance.TruncateTable<UnitCodeTest22>();
+            Db.CodeFirst.InitTables<UnitCodeTest3>();
+            Db.Insertable(new UnitCodeTest22() {  id=1}).ExecuteCommand();
         }
+ 
+        public class UnitCodeTest22 {
+             [SqlSugar.SugarColumn(IsNullable =true)]
+             public decimal? id { get; set; }
+        }
+        [SqlSugar.SugarTable("UnitCodeTest22")]
+        public class UnitCodeTest3
+        {
+            [SqlSugar.SugarColumn(IsNullable = false)]
+            public int id { get; set; }
+        }
+
         public class UnitCodeTest1
         {
             [SqlSugar.SugarColumn(IndexGroupNameList = new string[] { "group1" })]

Src/Asp.Net/SqlSugar/Realization/PostgreSQL/DbMaintenance/PostgreSQLDbMaintenance.cs

@@ -237,9 +237,33 @@ namespace SqlSugar
                 return "serial";
             }
         }
-          #endregion
+        #endregion
 
         #region Methods
+        public override bool UpdateColumn(string tableName, DbColumnInfo columnInfo)
+        {
+            tableName = this.SqlBuilder.GetTranslationTableName(tableName);
+            var columnName= this.SqlBuilder.GetTranslationColumnName(columnInfo.DbColumnName);
+            string sql = GetUpdateColumnSql(tableName, columnInfo);
+            this.Context.Ado.ExecuteCommand(sql);
+            var isnull = columnInfo.IsNullable?" SET NOT NULL ":" DROP NOT NULL ";
+            this.Context.Ado.ExecuteCommand(string.Format("alter table {0} alter {1} {2}",tableName,columnName, isnull));
+            return true;
+        }
+
+        protected override string GetUpdateColumnSql(string tableName, DbColumnInfo columnInfo)
+        {
+            string columnName = this.SqlBuilder.GetTranslationColumnName(columnInfo.DbColumnName);
+            tableName = this.SqlBuilder.GetTranslationTableName(tableName);
+            string dataSize = GetSize(columnInfo);
+            string dataType = columnInfo.DataType;
+            string nullType = "";
+            string primaryKey = null;
+            string identity = null;
+            string result = string.Format(this.AlterColumnToTableSql, tableName, columnName, dataType, dataSize, nullType, primaryKey, identity);
+            return result;
+        }
+
         /// <summary>
         ///by current connection string
         /// </summary>