判断数据查询结果

[diamond_back]

select top 1 "column name1" from table where column name2= 123456
用什么方法判断查询结果,如有数据则TEXTBOX.TEXT = column_name1查询出来的值,如果找不到数据则提示信息

[纯唇Yu弄]

[Quote=引用 1 楼 q107770540 的回复:]
string sql = "select top 1 "column name1" from table where column name2= 123456";
using (SqlConnection conn = new SqlConnection(connString))
{
SqlCommand cmd = new SqlCommand(sq……
[/Quote]

顶 +1

TEXTBOX.TEXT =cmd.ExecuteScalar()==null?"提示信息!":(string)cmd.ExecuteScalar();

[kingdom_0]

[Quote=引用 7 楼 li_1042237864 的回复:]

引用 1 楼 q107770540 的回复:
string sql = "select top 1 "column name1" from table where column name2= 123456";
using (SqlConnection conn = new SqlConnection(connString))
{
SqlCommand cmd = new SqlComma……
[/Quote]
+1.

[jodem]

string sql = "select top 1 "column name1" from table where column name2= 123456";
using (SqlConnection conn = new SqlConnection(connString))
{
SqlCommand cmd = new SqlCommand(sq……

[davidcoffee]

[Quote=引用 1 楼 q107770540 的回复:]
string sql = "select top 1 "column name1" from table where column name2= 123456";
using (SqlConnection conn = new SqlConnection(connString))
{
SqlCommand cmd = new SqlCommand(sql, conn);
……
[/Quote]
cmd.ExecuteScalar();

[q107770540]

string sql = "select top 1 "column name1" from table where column name2= 123456";
using (SqlConnection conn = new SqlConnection(connString))
{
SqlCommand cmd = new SqlCommand(sql, conn);

try
{
conn.Open();
TEXTBOX.TEXT =cmd.ExecuteScalar()==null?"":(string)cmd.ExecuteScalar();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}

[sfxdawn]

查Top 1 的話，而且只查詢一個字段的話，用樓上的ExecuteScalar()方法來獲取第一行第一列的值最好不過了。

[diamond_back]

如果不用try ... catch...呢?

[堆代码的爱因斯坦]

[Quote=引用 3 楼 diamond_back 的回复:]
如果不用try ... catch...呢?
[/Quote]
那错了，就抛出异常呗

[gio301]

复制了q107770540,这个最适合了

string message = cmd.ExecuteScalar();
TEXTBOX.TEXT =String.IsNullOrEmpty(message)?message:"提示信息！";

[diamond_back]

可能误会了
create table staff
(staff_id varchar (13),
staff_name varchar (15))

insert INTO STAFF values
('1234','apple')
insert INTO STAFF values
('1235','MAY')
insert INTO STAFF values
('1236','ORANGE')

select top 1 staff_name from STAFF where staff_id = ‘1236’
输入正确的staff_id，则将orange显示在textbox.text上

select top 1 staff_name from STAFF where staff_id = ‘1238’
输入错误的staff_id，则显示"1238不是有效的staff_id"