# And $ symbols in ibatis2.3 (conversion)

Source: Internet
Author: User

在Ibatis中我们使用SqlMap进行Sql查询时需要引用参数,在参数引用中遇到的符号#和$之间的区分为,#可以进行与编译,进行类型匹配,而$不进行数据类型匹配,例如: select * from table where id = #id# ,其中如果字段id为字符型,那么#id#表示的就是‘id‘类型,如果id为整型,那么#id#就是id类型。 select * from table where id = $id$ ,如果字段id为整型,Sql语句就不会出错,但是如果字段id为字符型,那么Sql语句应该写成 select * from table where id = ‘$id$‘$ 的作用实际上是字符串拼接, 
select * from $tableName$ 
StringBuffer sb = new StringBuffer(256); 
sb.append("select * from ").append(tableName); 

select * from table where id = #id# 
prepareStement = stmt.createPrepareStement("select * from table where id = ?") 


说道这里, 总结一下, 什么时候用$,什么时候 用 # 

对于变量部分, 应当使用#, 这样可以有效的防止sql注入, 未来,# 都是用到了prepareStement,这样对效率也有一定的提升 

$只是简单的字符拼接而已,对于非变量部分, 那只能使用$, 实际上, 在很多场合,$也是有很多实际意义的 
select * from $tableName$ 对于不同的表执行统一的查询 
update $tableName$ set status = #status# 每个实体一张表,改变不用实体的状态 
特别提醒一下, $只是字符串拼接, 所以要特别小心sql注入问题。

# And $ symbols in ibatis2.3 (conversion)

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