FreeMarker复杂用法记录

完整教程：

什么是 FreeMarker? - FreeMarker 中文官方参考手册

用法一

 //先初始化要拼接的字符串头
<#assign sqlCol=" sum(if(classify_name = '塑料',sum_quantity,0)) as '塑料' ">
//定于需要拼接的字符串，上面哪个熟料也属于这个分类，如果后面，直接在数组后面加就行了
<#assign classify = ['废木板','废铜','木板','水泥','泡沫','炼钢','炼铁','玻璃','瓷砖','电池','纸皮','陶瓷'] >
<#list classify as cName>
	//拼接select 后面的列查询，如果该分类为cName,那么这列就加值
   <#assign sqlCol=sqlCol+", sum(if(classify_name = '${cName}',sum_quantity,0)) as '${cName}' ">

//前端发来的条件
 <#if monthAt??>

    <#assign substrConditionMain="SUBSTR(main.create_time,9 , 2)">
    <#assign substrConditionSlave="SUBSTR(create_time,9 , 2)">
    <#assign timeSuffixStart=monthAt+"-01">
  //freemarkter里面的语法，截取字符串5-6号位置字符，从0开始
    <#assign currentMonth = monthAt[5..6]>
      select 
      //强行填充一列自定义的数据进去
         IFNULL(null,'${timeSuffixStart}') as 'create_time', -- string -- 日期
         ${sqlCol}
      from iot.weight_statistic_ads 
      where 
         create_time = '${timeSuffixStart}' and project_code = "${projectCode}"
//产生一个循环，从2-get_days_in_month(monthAt[0..3]?number,monthAt[5..6]?number)
//get_days_in_month是一个函数
   <#list 2..get_days_in_month(monthAt[0..3]?number,monthAt[5..6]?number) as num>
      
      <#if num < 10 >
         <#assign qTime = monthAt+'-0'+num>
      <#else>
         <#assign qTime = monthAt+'-'+num>
      
      
      UNION ALL
           
               select 
               IFNULL(create_time,'${qTime}') as 'create_time',
               ${sqlCol}
               from iot.weight_statistic_ads 
               where 
                  create_time = '${qTime}' and project_code = "${projectCode}"
          

   
 

 <#if yearAt??>
    <#assign substrConditionMain="SUBSTR(main.create_time,1 , 7)">
    <#assign substrConditionSlave="SUBSTR(create_time,1 , 7)">
    <#assign timeSuffixStart=yearAt+"-01">

      select 
         IFNULL(null,'${timeSuffixStart}') as 'create_time', -- string -- 日期
         ${sqlCol}
      from iot.weight_statistic_ads 
      where
         create_time >= '${timeSuffixStart+"-01"}' and create_time <= '${timeSuffixStart+"-31"}' 
         and project_code = "${projectCode}"

   <#list 2..12 as num>
      
      <#if num < 10 >
         <#assign qTime = yearAt+'-0'+num >
      <#else>
         <#assign qTime = yearAt+'-'+num>
      
      
      UNION ALL
           
               select 
               IFNULL(create_time,'${qTime}') as 'create_time',
               ${sqlCol}
               from iot.weight_statistic_ads 
               where 
                  create_time >= '${qTime+"-01"}' and create_time <= '${qTime+"-31"}' 
                  and project_code = "${projectCode}"
   
 

//定义函数，函数名称  参数1，参数2
<#function get_days_in_month year month>  
   <#assign days = 0>  
   <#if month==2 >  
       <#if (year % 4)==0 >  
             <#assign days = 28>  
       <#else>  
             <#if (year % 100)==0>  
                <#assign days = 29>  
             <#else>  
                <#if (year % 400)==0>  
                   <#assign days = 28>  
                <#else>  
                   <#assign days = 29>  
                  
               
         
   <#else>  
       <#if (month == 4)||(month == 6)||(month == 9)||(month == 11) >  
             <#assign days = 30>  
       <#else>  
             <#assign days = 31>  
         
     
   <#return days >