Question

我想查询数据，列（大陆）的值为'Africa'或Null。

我想在我的查询中使用此列名称，但对于名称不是非洲的国家/地区，我没有数据。

这是我尝试的但没有返回数据。

SqlDataAdapter dba = new SqlDataAdapter(@"SELECT * from [tblCountries] 
                     WHERE [Continent] = '' order by [Common Name]", connection);
                    //WHERE [Continent]<>'Africa' order by [Common Name]", connection);
                   //WHERE [Continent] IS null order by [Common Name]", connection);
dba.Fill(ds);

drpNonAfricanCountries.DataSource = ds;

这样做的正确方法是什么？

Answer 1

我想查询数据，列（Continent）的值为 '非洲'或无。

WHERE [Continent] = 'Africa' OR  [Continent] IS NULL

使用NULL使用IS NULL

比较列

所以你的最终代码应该是：

SqlDataAdapter dba = new SqlDataAdapter(@"SELECT * from [tblCountries] 
               WHERE [Continent] = 'Africa' OR  [Continent] IS NULL order by [Common Name]", connection);

Answer 2

试试这个

SqlDataAdapter dba = new SqlDataAdapter(@"SELECT * from [tblCountries] 
                                     WHERE [Continent] IS NULL order by [Common Name]", connection);
            dba.Fill(ds);
            drpNonAfricanCountries.DataSource = ds;

Answer 3

select * from tblCountries where (Continent = 'Africa' or Continent is null)

Answer 4

试试这个：

SELECT [from [tblCountries] WHERE [Continent] IS NULL或[Continent] ='Africa'的顺序由[Common Name];

选择column ='null'的数据

4 个答案: