/// <summary>
/// 执行选择单个值的参数化SQL。
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="sql"></param>
/// <param name="parameters"></param>
/// <param name="commandType"></param>
/// <returns></returns>
public T ExecuteScalar <T>(string sql, DynamicParameters parameters = null, CommandType?commandType = null)
{
if (CurrentTransaction != null)
{
return(DbExecProxy <T>((param) => CurrentConnection.ExecuteScalar <T>(sql, param, CurrentTransaction, CommandTimeout, commandType), sql, parameters));
}
using var connection = GetDbConnection(DataSourceEnum.SLAVE);
return(DbExecProxy <T>((param) => connection.ExecuteScalar <T>(sql, param, CurrentTransaction, CommandTimeout, commandType), sql, parameters));
}
/// <summary>
/// 条件判断是否存在
/// </summary>
/// <returns>是否存在</returns>
/// <param name="predicate">判断条件委托</param>
public bool Exist <T>(Expression <Func <T, bool> > predicate = null)
where T : ModelBase
{
string tableName = GetTableName <T>();
QueryResult queryResult = DynamicQuery.GetDynamicQuery(tableName, predicate);
object result = CurrentConnection.ExecuteScalar(queryResult.Sql, (object)queryResult.Param, CurrentTransaction);
return(result != null);
}