如何让这个IF语句跳到另一个语句？

Question

我该如何让这个If语句跳到下面的if语句？然后，我尝试了其他方法，但它不起作用。无论输入是否传入变量，我都希望它显示。

declare @sql varchar(8000) 
declare @sql_where varchar(8000) 

declare @ww varchar(10) 
declare @plant varchar(10) 
declare @plnr_id varchar(10) 

set @plant = 'CS58' 
set @ww = '201240' 
set @plnr_id = 'G37' 

set @sql_where = 'where' 
set @sql = 'select * from rout_sub_doi ' 

if len(@plant) > 0 
    set @sql_where = @sql_where + ' plant = ''' + @plant + ''' ' 

if len(@ww) > 0 
    set @sql_where = @sql_where + 'AND sys_intel_ww = ''' + @ww + ''' ' 

if len(@plnr_id) > 0 

    set @sql_where = @sql_where + ' AND plnr_id = ''' + @plnr_id + ''' ' 


print @sql 
print @sql_where 

exec (@sql + @sql_where) 

Answer 1

处理未知数量的条件的常用方法是使第一个WHERE 1=1或良性的东西，如WHERE id IS NOT NULL当ID被称为是不是空的。

declare @sql varchar(8000) 
declare @sql_where varchar(8000) 

declare @ww varchar(10) 
declare @plant varchar(10) 
declare @plnr_id varchar(10) 

set @plant = 'CS58' 
set @ww = '201240' 
set @plnr_id = 'G37' 

set @sql_where = '' 
set @sql = 'select * from rout_sub_doi where 1=1 ' 

if len(@plant) > 0 
    set @sql_where = @sql_where + 'AND plant = ''' + @plant + ''' ' 

if len(@ww) > 0 
    set @sql_where = @sql_where + 'AND sys_intel_ww = ''' + @ww + ''' ' 

if len(@plnr_id) > 0 
    set @sql_where = @sql_where + 'AND plnr_id = ''' + @plnr_id + ''' ' 

print @sql 
print @sql_where 

exec (@sql + @sql_where)