What is dynamic SQL?

Question

I just asked an SQL related question, and the first answer was: \"This is a situation where dynamic SQL is the way to go.\"

As I had never heard of

Answer 1

Dynamic SQL is a SQL built from strings at runtime. It is useful to dynamically set filters or other stuff.

An example:

declare @sql_clause varchar(1000)  
declare @sql varchar(5000)   


set @sql_clause = ' and '    
set @sql = ' insert into #tmp  
 select   
   *
from Table 
where propA = 1 '    

if @param1 <> ''    
begin    
   set @sql = @sql + @sql_clause + ' prop1 in (' + @param1 + ')'    
end    
if @param2 <> ''    
begin    
   set @sql = @sql + @sql_clause + ' prop2 in (' + @param2 + ')'    
end 

exec(@sql)