Function check_B(ByVal b As String) As Boolean '定义一个函数，判断数据库中是否存在当前 id Dim con A

Function check_B(ByVal b As String) As Boolean '定义一个函数，判断数据库中是否存在当前 id
Dim con As New OleDbCommand
Dim cmd As OleDbCommand
Dim strsql As String
Dim conn As OleDbConnection
strsql = "select * from reader where userid='" & b & "'" '注释：查询数据库中的reader表
cmd = New OleDbCommand(strsql, con)（语句一）
cmd.Connection.Open()
con = cmd.ExecuteReader()
check_B = False
While con.Read
check_B = True
End While
End Function
请问这个里面的详细讲解

public class Test
{
public static void main(String[] args)
{
long l = 12334L;
boolean bl = true;
double db = 13253.3453d;
string s = "String";
System.out.println(l);
System.out.println(bl);
System.out.println(db);
System.out.println(s);
}
}
文件名为Test.java

也许是的。

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