/// <summary>
/// 执行选择操作，返回SqlDataReader
/// </summary>
/// <param name="connectionString"></param>
/// <param name="creator"></param>
/// <returns></returns>
public static SqlDataReader SelectReader(string connectionString, SqlCreator creator)
{
string sql = creator.GetSelectSql();
var par = new SqlParameter[creator.WhereColumns.Length];
for (int i = 0; i < creator.WhereColumns.Length; i++)
{
Column parm = creator.WhereColumns[i];
par[i] = MakeInputParam(parm.ParameterName, parm.DbType, parm.Size, parm.Value);
}
return ExecuteReader(connectionString, CommandType.Text, sql, par);
}
/// <summary>
/// 判断是否存在一条记录
/// </summary>
/// <param name="connectionString">连接字符串</param>
/// <param name="creator">判断条件</param>
/// <returns></returns>
public static bool Exists(string connectionString, SqlCreator creator)
{
creator.Columns = new[]
{
new Column("count(1)")
};
var par = new SqlParameter[creator.WhereColumns.Length];
for (int i = 0; i < creator.WhereColumns.Length; i++)
{
Column parm = creator.WhereColumns[i];
par[i] = MakeInputParam(parm.ParameterName, parm.DbType, parm.Size, parm.Value);
}
object obj = ExecuteScalar(connectionString, CommandType.Text,
creator.GetSelectSql(),
par);
int count = int.Parse(obj.ToString());
return count > 0;
}