请教SQL语言中单引号和双引号的区别

xuxiabiao

我要修改一张表的一条记录
update aaa set col1='select * from bbb ';报语法错误
update aaa set col1="select * from bbb";update成功
我就很奇怪为什么单引号执行失败而双引号执行成功。
而以下的sql语句的单引号和双引号效果一样
select * from aaa where col1='abc';
select * from aaa where col1="abc";

liaosnet

原帖由 xuxiabiao 于 2008-10-10 16:02 发表
我要修改一张表的一条记录
update aaa set col1='select * from bbb ';报语法错误
update aaa set col1="select * from bbb";update成功
我就很奇怪为什么单引号执行失败而双引号执行成功。
而以下的sql语句 ...

有这样的情况?~??

<56 www [informix] :/opt/informix>dbaccess testdb -

Database selected.

> update t1 set des = "select * from t1 where id=2;" ;

2 row(s) updated.

> update t1 set des = 'select * from t1 where id=1;';

2 row(s) updated.

liaosnet

到是应该如果设置了DELIMIDENT变量的话可以导致........
> update t1 set des="select * from t1 where id=1";

  217: Column (select * from t1 where id=1) not found in any table in the query (or SLV is undefined).
Error in line 1
Near character position 47

xuxiabiao

DELIMIDENT这个变量如何修改啊