解释一下这个sql,<if test=" source !=null"> and t.source=#{source}</if><if test=" participant !=null and participant.size()>0 ">AND EXISTS (SELECT1FROMims_roadshow_contact t2WHEREt2.roadshow_id = t.schedule_id AND t2.id_type = 2AND t2.participant_account IN (<foreach collection="participant" item="item" separator=", ">#{item.account}</foreach></if>
时间: 2024-03-29 18:39:52 浏览: 18
这是一个MyBatis中的动态SQL语句,主要作用是根据不同的条件动态生成SQL语句,其中if和foreach标签是MyBatis中的动态语句标签。
这个SQL语句的作用是根据条件筛选出符合要求的数据。其中,<if test=" source !=null">表示如果source不为空,则在SQL语句中加入and t.source=#{source}这个条件;<if test=" participant !=null and participant.size()>0 ">表示如果participant不为空且其长度大于0,则在SQL语句中加入AND EXISTS (SELECT 1 FROM ims_roadshow_contact t2 WHERE t2.roadshow_id = t.schedule_id AND t2.id_type = 2 AND t2.participant_account IN (<foreach collection="participant" item="item" separator=", ">#{item.account}</foreach>这个条件。
其中,<foreach>标签是遍历participant集合中的每个元素,将其拼接到SQL语句中,separator指定拼接时使用的分隔符,item指代集合中的元素,#{item.account}表示获取元素的account属性的值。
相关问题
优化这段sql:select `id`, `createDate`, `signalSourceSetValue`, `signalSourceTrueValue`, `receiveSignalAmplitude`, `transmitSignalAmplitude`, `simulationSetValue`, `simulationTrueValue`, `amplitude`, `frequency` from simulation_target_and_signal_source_truth_t <if test="frequency != null and frequency != '' "> where `createDate` = ( select Max(`createDate`) as 'createDate' from simulation_target_and_signal_source_truth_t where CONVERT (`frequency`,DECIMAL) = CONVERT( #{frequency},DECIMAL) ) </if> <if test="frequency == null or frequency == ''"> where `createDate` in ( SELECT DISTINCT FIRST_VALUE(`createDate`) over (PARTITION BY `frequency` ORDER BY `createDate`) AS 'createDate' FROM simulation_target_and_signal_source_truth_t ) </if>
首先,尝试将 `CONVERT (`frequency`,DECIMAL)` 改为 `CAST(frequency AS DECIMAL)`,这可以提高查询效率。
其次,可以把 `Max(`createDate`)` 改为 `SELECT TOP 1 createDate FROM ... ORDER BY createDate DESC` 的形式,也可以提高查询效率。这样查询最大的日期时不会返回所有日期,只会返回一个日期。
最后,如果 `frequency` 是一个经常被查询的字段,可以为该字段创建一个索引,以提高查询效率。
修改后的SQL如下:
```sql
SELECT `id`,
`createDate`,
`signalSourceSetValue`,
`signalSourceTrueValue`,
`receiveSignalAmplitude`,
`transmitSignalAmplitude`,
`simulationSetValue`,
`simulationTrueValue`,
`amplitude`,
`frequency`
FROM simulation_target_and_signal_source_truth_t
<if test="frequency != null and frequency != '' ">
WHERE `createDate` = (
SELECT TOP 1 createDate
FROM simulation_target_and_signal_source_truth_t
WHERE CAST(frequency AS DECIMAL) = CAST(#{frequency} AS DECIMAL)
ORDER BY createDate DESC
)
</if>
<if test="frequency == null or frequency == ''">
WHERE `createDate` IN (
SELECT DISTINCT
FIRST_VALUE(`createDate`) over (PARTITION BY `frequency` ORDER BY `createDate`) AS 'createDate'
FROM simulation_target_and_signal_source_truth_t
)
</if>
```
以上是一些简单的优化方法,根据实际情况可能还需要进一步的优化。
改如何修正: <select id="getCurrentTask" resultType="com.sottop.sokonmobile.sokonmobile.qingdao.entity.AsEmWorkOrderEntity"> 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=#{executor} <if test="orderType!=null and orderType!=''"> AND asewo.order_type_s=#{orderType} </if> ORDER BY asewo.creation_time DESC Union All 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.ORDER_STATUS_S='创建' AND asewo.executor_s=#{executor} <if test="orderType!=null and orderType!=''"> AND asewo.order_type_s=#{orderType} </if> ORDER BY asewo.creation_time DESC </select>
根据您提供的信息,似乎这个SQL语句存在一些问题,包括:
1. 在第一行的resultType中,应该使用全限定类名而非实体类名。
2. 在第6行的SQL语句中,应该使用小于等于(<=)而非HTML实体字符(<=)。
3. 在第18行和第30行的ORDER BY子句中,应该使用ORDER BY asewo.creation_time DESC,而非ORDER BY creation_time DESC。因为创建时间(creation_time)是AT_AS_EM_Work_Order表中的列,需要使用别名asewo来引用。
修正后的SQL语句如下所示:
```
<select id="getCurrentTask" resultType="com.sottop.sokonmobile.sokonmobile.qingdao.entity.AsEmWorkOrderEntity">
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(asewo.plan_finish_time_T,'yyyy_mm_dd hh24:mi')
AND asewo.ORDER_STATUS_S='创建'
AND asewo.executor_s=#{executor}
<if test="orderType!=null and orderType!=''">
AND asewo.order_type_s=#{orderType}
</if>
ORDER BY asewo.creation_time DESC
Union All
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.ORDER_STATUS_S='创建'
AND asewo.executor_s=#{executor}
<if test="orderType!=null and orderType!=''">
AND asewo.order_type_s=#{orderType}
</if>
ORDER BY asewo.creation_time DESC
</select>
```