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1.在数据库表里面设置一个唯一索引(唯一索引必须是不会重复的字段)2.使用 REPLACE INTO 语句 <insert id="listFireDeviceWaterInsert"> REPLACE INTO fire_control_water ( DEVICE_NO,//这个字段是你在数据库表里面定义的唯一索引 ID, DEVICE_NAME, COMPANY_ID, COMPANY_NAME ) value

一.sql语句查询分布在多张表内的字段相同的数据1.看代码select bi.basic_id as basicId, s.create_time as reportTimefrom construction_area_base_facility_supervise sleft join basic_info bi on bi.basic_id=s.basic_info_idwhere 1=1 and s.is_history=0union allselect

1.sql语句中使用if改变列的值和sql语句根据月份分组并判断高级条件的语法(1)使用if改变列的值的sql语句SELECT sum(( ( IF ( plan_invested_amount_centre IS NULL, 0, plan_invested_amount_centre ) ) * ( IF ( invest_money_unit_centre = 2, 6.992, 1 ) ) ) + ( ( IF ( plan_invested_amount_outer IS NULL,

1.sql语句，根据月份分组进行查询(1)数据库的格式CREATE TABLE `project_info` (`project_id` VARCHAR ( 64 ) NOT NULL COMMENT '项目信息表id',`project_name` VARCHAR ( 255 ) NOT NULL COMMENT '项目名称',`take_the_lead` VARCHAR ( 50 ) DEFAULT NULL COMMENT '牵头单位',`industry_id` INT ( 11

1.一条sql语句查询多个条件的写法(1)sql语句的使用SELECT p1.count1 AS todayAdd,p2.count2 AS todayReturns,p3.count3 AS sameMonthAdd,p4.count4 AS lastMonthAdd FROM (SELECT COUNT(create_time)count1 FROM project_info WHERE TO_DAYS(create_time)=TO_DAYS(SYSDATE())) AS p