您的 SQL 语法错误，.net 的 mysql 连接器

Question

存储过程：

CREATE DEFINER=`newdb`@`%` PROCEDURE `GetMaximumIDsCount`(IN AppID INT,IN isBurnCenter INT,IN BurnCenterID INT)
BEGIN

    IF isBurnCenter = 1 THEN

    SELECT MAX(CAST(b.hospitalid AS SIGNED))

    FROM tblhosipital b

    WHERE b.appId = AppID AND b.burncenterid IS NULL;

    END IF;


    IF isBurnCenter = 0 THEN

    SELECT MAX(CAST(h.hospitalid AS SIGNED))

    FROM tblhosipital h

    WHERE h.appId = AppID AND h.burncenterid <> '' AND h.burncenterid = BurnCenterID;

    END IF;
END

从 ApplicationDbContext 调用（代码优先）

public virtual ObjectResult<long?> GetMaximumIDsCount2(Nullable<int> appID, Nullable<int> isBurnCenter, Nullable<int> burnCenterID)
        {
            var appIDParameter = appID.HasValue ?
                new ObjectParameter("AppID", appID) :
                new ObjectParameter("AppID", typeof(int));

            var isBurnCenterParameter = isBurnCenter.HasValue ?
                new ObjectParameter("isBurnCenter", isBurnCenter) :
                new ObjectParameter("isBurnCenter", typeof(int));

            var burnCenterIDParameter = burnCenterID.HasValue ?
                new ObjectParameter("BurnCenterID", burnCenterID) :
                new ObjectParameter("BurnCenterID", typeof(int));

            return ((IObjectContextAdapter)this).ObjectContext.ExecuteStoreQuery<Nullable<long>>("GetMaximumIDsCount @AppID, @isBurnCenter, @BurnCenterID", appIDParameter, isBurnCenterParameter, burnCenterIDParameter);
        }

获取异常：

您的 SQL 语法有错误；检查手册 对应于您的 MySQL 服务器版本，以便使用正确的语法 在'GetMaximumIDsCount @AppID，@isBurnCenter，@BurnCenterID'附近 1

Answer 1

需要在存储过程名称前加上CALL [procedure_name]()方法：

return ((IObjectContextAdapter)this)
       .ObjectContext
       .ExecuteStoreQuery<List<long?>>("CALL GetMaximumIDsCount(@AppID, @isBurnCenter, @BurnCenterID)", 
       appIDParameter, isBurnCenterParameter, burnCenterIDParameter);

注意： MySQL 存储过程使用以下语法执行：

CALL procedure_name(parameter_list)

注意2：使用FirstOrDefault()或SingleOrDefault()从ObjectResult<T>返回一个结果集：

var x = db.GetMaximumIDsCount2(...).FirstOrDefault();

附带说明，您可以尝试使用MySqlParameter 而不是ObjectParameter 声明参数：

// you can change DBNull.Value with any appropriate value

var appIDParameter = new MySqlParameter("AppID", MySqlDbType.Int).Value = (appID.HasValue) ? appID : DBNull.Value;

var isBurnCenterParameter = new MySqlParameter("isBurnCenter", MySqlDbType.Int).Value = (isBurnCenter.HasValue) ? isBurnCenter : DBNull.Value;

var isBurnCenterParameter = new MySqlParameter("BurnCenterID", MySqlDbType.Int).Value = (burnCenterID.HasValue) ? burnCenterID : DBNull.Value;

参考：

CALL Syntax (MySQL)