ISNULL

Question

我有一个表，其中列levdat是DateTime数据类型。它的值由文本框插入。有时它可以为null。我希望每当textbox为空时将null插入到数据库列中。但它正在插入 0001-01-01 00:00:00 。我的代码是

string date3=txt_lev_dat.Text;
if (date3 != "")
{
    if ((!DateTime.TryParse(date3, out datetime)) && (date3 != ""))
    {
        lbl_lev_war.Text = "Incorrect Date";
        lbl_lev_war.ToolTip = "Please Enter Correct Date";
    }
    else
    {
        objprp.p_tchlevdat = Convert.ToDateTime(date3);
    }
}

我试图输入DBnull.value。但它给了我错误。提前致谢。我的商店程序是

DELIMITER $$

 DROP PROCEDURE IF EXISTS `db_school_management`.`ins_tch`$$

       CREATE PROCEDURE `db_school_management`.`ins_tch`(citycod INT,_statecod INT,_tchfstnam       VARCHAR(50),_tchlstnam VARCHAR(50),_tchfatnam VARCHAR(50),
    _tchmotnam VARCHAR(50),_tchdob DATETIME,_tchgen VARCHAR(5),_tchadd VARCHAR(200),_tchmob VARCHAR(20),_tchphn VARCHAR(20),_tchzipcod VARCHAR(10),
    _tchedu VARCHAR(50),_tchsal INT,_tcheml VARCHAR(50),_tchusrnam VARCHAR(50),_tchpwd VARCHAR(50),_tchjoindat DATETIME,_tchpic VARCHAR(50),_tchlevdat DATETIME,_flag VARCHAR(5))
        BEGIN
    INSERT INTO tbteacher(citycod,statecod,tchfstnam,tchlstnam,tchfatnam,tchmotnam,tchdob,tchgen,tchadd,tchmob,tchphn,tchzipcod,tchedu,tchsal,
    tcheml,tchusrnam,tchpwd,tchjoindat,tchpic,tchlevdat,flag) VALUES(_citycod,_statecod,_tchfstnam,_tchlstnam,_tchfatnam,_tchmotnam,_tchdob,_tchgen,
    _tchadd,_tchmob,_tchphn,_tchzipcod,_tchedu,_tchsal,_tcheml,_tchusrnam,_tchpwd,_tchjoindat,_tchpic,_tchlevdat,_flag);
        END

Answer 1

您可以在MySQL中使用ISNULL属性

ISNULL

喜欢这个

ISNULL(levdat,'')

试试这个

DELIMITER $$

 DROP PROCEDURE IF EXISTS `db_school_management`.`ins_tch`$$

 CREATE PROCEDURE `db_school_management`.`ins_tch`
     (citycod INT,_statecod INT,_tchfstnam       VARCHAR(50),_tchlstnam VARCHAR(50),_tchfatnam   VARCHAR(50),
    _tchmotnam VARCHAR(50),_tchdob DATETIME,_tchgen VARCHAR(5),_tchadd VARCHAR(200),_tchmob VARCHAR(20),_tchphn VARCHAR(20),_tchzipcod VARCHAR(10),
    _tchedu VARCHAR(50),_tchsal INT,_tcheml VARCHAR(50),_tchusrnam VARCHAR(50),_tchpwd VARCHAR(50),_tchjoindat DATETIME,_tchpic VARCHAR(50),_tchlevdat DATETIME,_flag VARCHAR(5))
 BEGIN
    INSERT INTO tbteacher(citycod,statecod,tchfstnam,tchlstnam,tchfatnam,tchmotnam,tchdob,tchgen,tchadd,tchmob,tchphn,tchzipcod,tchedu,tchsal,
    tcheml,tchusrnam,tchpwd,tchjoindat,tchpic,tchlevdat,flag) VALUES(_citycod,_statecod,_tchfstnam,_tchlstnam,_tchfatnam,_tchmotnam,ISNULL(_tchdob,''),_tchgen,        _tchadd,_tchmob,_tchphn,_tchzipcod,_tchedu,_tchsal,_tcheml,_tchusrnam,_tchpwd,_tchjoindat,_tchpic,ISNULL(_tchlevdat,''),_flag);
 END

如何在c＃中的mysql的datetime列中插入null值

1 个答案:

ISNULL