to_char(actual_create_time,'yyyy-mm-dd') >= to_char(sysdate - 5,'yyyy-mm-dd') 是什么意识

这是一条 SQL 语句，它的作用是将 actual_create_time 字段转换为年-月-日格式，并与当前日期减去 5 天后的日期比较，如果 actual_create_time 字段日期大于或等于当前日期减去 5 天后的日期，则返回 true，否则返回 false。换句话说，它的意思是选择 actual_create_time 字段在过去 5 天内的记录。

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帮我解释一下 PID_TypeDef g_location_pid; /* 位置PID参数结构体*/ /** * @brief 初始化PID参数 * @param 无 * @retval 无 / void pid_init(void) { /位置环初始化/ g_location_pid.SetPoint = (float)(50PPM); /* 设定目标Desired Value*/ g_location_pid.ActualValue = 0.0; /* 期望值*/ g_location_pid.SumError = 0.0; /* 积分值*/ g_location_pid.Error = 0.0; /* Error[1]/ g_location_pid.LastError = 0.0; / Error[-1]/ g_location_pid.PrevError = 0.0; / Error[-2]/ g_location_pid.Proportion = L_KP; / 比例常数 Proportional Const*/ g_location_pid.Integral = L_KI; /* 积分常数 Integral Const*/ g_location_pid.Derivative = L_KD; /* 微分常数 Derivative Const*/ g_location_pid.IngMax = 20; g_location_pid.IngMin = -20; g_location_pid.OutMax = 150; /* 输出限制 / g_location_pid.OutMin = -150; } /* * 函数名称：位置闭环PID控制设计 * 输入参数：当前控制量 * 返 回 值：目标控制量 * 说 明：无 */ int32_t increment_pid_ctrl(PID_TypeDef PID,float Feedback_value) { PID->Error = (float)(PID->SetPoint - Feedback_value); / 偏差 / #if INCR_LOCT_SELECT PID->ActualValue += (PID->Proportion * (PID->Error - PID->LastError)) / E[k]项 / + (PID->Integral * PID->Error) / E[k-1]项 / + (PID->Derivative * (PID->Error - 2 * PID->LastError + PID->PrevError)); / E[k-2]项 / PID->PrevError = PID->LastError; / 存储误差，用于下次计算 / PID->LastError = PID->Error; #else PID->SumError += PID->Error; if(PID->SumError > PID->IngMax) { PID->SumError = PID->IngMax; } else if(PID->SumError < PID->IngMin) { PID->SumError = PID->IngMin; } PID->ActualValue = (PID->Proportion * PID->Error) / E[k]项 / + (PID->Integral * PID->SumError) / E[k-1]项 / + (PID->Derivative * (PID->Error - PID->LastError)); / E[k-2]项 / PID->LastError = PID->Error; #endif if(PID->ActualValue > PID->OutMax) { PID->ActualValue = PID->OutMax; } else if(PID->ActualValue < PID->OutMin) { PID->ActualValue = PID->OutMin; } return ((int32_t)(PID->ActualValue)); / 返回实际控制数值 */ }

这段代码是一个PID控制器的实现，用于控制某个系统的输出值达到设定值。PID控制器包含比例、积分、微分三个控制参数，分别代表了控制器对于当前误差的处理方式。在这段代码中，PID控制器的参数结构体为`PID_TypeDef`，包含了设定目标值、实际值、误差、累积误差、上一次误差、上上次误差以及比例、积分、微分三个控制参数。`pid_init()`函数用于初始化PID参数，`increment_pid_ctrl()`函数是PID控制器的主要实现函数，在该函数中根据不同的控制方式（增量式或位置式），计算出实际控制值并返回。其中，增量式控制方式需要多个误差值的参与计算，而位置式控制方式只需要当前误差值即可。

帮我优化这段sql：SELECT asewo.code_s as code,asewo.order_type_s as orderType,asewo.equipment_name_s as equipmentName,asewo.executor_s as executor, asewo.plan_start_time_T as planStartTime,asewo.plan_finish_time_T as planFinishTime,asewo.tpm_key_s as tpmKey,asewo.shop_s as shop, asewo.line_S as line,asewo.actual_start_time_t as startTime,asewo.actual_finish_time_t as finishTime,asewo.executor_account_s as executorAccounts, asewo.source_type_s as sourceType,asewo.SOURCE_ORDER_S as sourceOrder,asewo.CREATION_TIME as creationTime FROM AT_AS_EM_Work_Order asewo WHERE to_char(asewo.plan_start_time_T,'yyyy_mm-dd hh24:mi') <= to_char(plan_finish_time_T,'yyyy_mm_dd hh24:mi') AND asewo.ORDER_STATUS_S='创建' AND asewo.executor_s='H007063' AND asewo.EQUIPMENT_NAME_S like '%机%' GROUP BY asewo.shop_s, asewo.line_S

可以尝试以下几种优化方式：

1. 建立索引：为了让查询更快速，可以在 `AT_AS_EM_Work_Order` 表中建立索引，包括 `plan_start_time_T`、`plan_finish_time_T`、`ORDER_STATUS_S`、`executor_s` 和 `EQUIPMENT_NAME_S` 字段。

2. 修改查询条件：可以将日期格式化的操作移动到查询条件外部，在查询条件内直接比较日期类型的字段。同时可以将 `GROUP BY` 字段减少到仅保留 `shop_s` 字段，这样可以让查询更快速。

修改后的 SQL 可以是这样的：

SELECT asewo.code_s as code,
       asewo.order_type_s as orderType,
       asewo.equipment_name_s as equipmentName,
       asewo.executor_s as executor,
       asewo.plan_start_time_T as planStartTime,
       asewo.plan_finish_time_T as planFinishTime,
       asewo.tpm_key_s as tpmKey,
       asewo.shop_s as shop,
       asewo.line_S as line,
       asewo.actual_start_time_t as startTime,
       asewo.actual_finish_time_t as finishTime,
       asewo.executor_account_s as executorAccounts,
       asewo.source_type_s as sourceType,
       asewo.SOURCE_ORDER_S as sourceOrder,
       asewo.CREATION_TIME as creationTime
FROM AT_AS_EM_Work_Order asewo
WHERE asewo.plan_start_time_T <= asewo.plan_finish_time_T
  AND asewo.ORDER_STATUS_S = '创建'
  AND asewo.executor_s = 'H007063'
  AND asewo.EQUIPMENT_NAME_S LIKE '%机%'
GROUP BY asewo.shop_s

3. 分批查询：如果数据量非常大，可以将查询分批进行，每次查询一部分数据，然后将结果合并。这样可以减少单次查询的数据量，从而提高查询效率。