SQL中select带括号语句怎么表达? 请问SQL语句中若字段名本身包含有方括号的SELECT语句该...
SQL\u4e2dselect\u5e26\u62ec\u53f7\u8bed\u53e5\u600e\u4e48\u8868\u8fbeCURRENT \u5f62\u5f0f\u7684UPDATE \u8bed\u53e5\u548cDELETE \u8bed\u53e5\u7684\u7528\u9014\u662f\u9762\u5411\u96c6\u5408\u7684\u64cd\u4f5c\uff0c\u4e00\u6b21\u64cd\u4f5c\u6240\u6709\u8bb0\u5f55\u3002\u5982\u679c\u53ea\u60f3\u4fee\u6539\u6216\u5220\u9664\u5176\u4e2d\u67d0\u4e2a\u8bb0\u5f55\uff0c\u7528\u5e26\u6e38\u6807\u7684SELECT \u8bed\u53e5\u67e5\u51fa\u6240\u6709\u6ee1\u8db3\u6761\u4ef6\u7684\u8bb0\u5f55\uff0c\u4ece\u4e2d\u8fdb\u4e00\u6b65\u627e\u51fa\u8981\u4fee\u6539\u6216\u5220\u9664\u7684\u8bb0\u5f55\uff0c\u7528CURRENT \u5f62\u5f0f\u7684UPDATE \u8bed\u53e5\u548cDELETE \u8bed\u53e5\u4fee\u6539\u6216\u5220\u9664\u4e4b \u3002
\u8bd5\u8bd5\u4f7f\u7528\u540e\u9762\u52a0\u53c2\u6570\u7684\u65b9\u5f0f\uff0c \u4ee5ASP.NET c#\u4e3a\u4f8b
\u9996\u5148\u5efa\u7acb\u4e00\u4e2aCOMMAND\u5bf9\u8c61
OleDbCommand mycmd = new OleDbCommand("select @canshu1,@canshu2 from \u8868\u540d\u201c, con);
\u5176\u4e2d@\u540e\u9762\u7684\u5c31\u662f\u53c2\u6570\uff0c
mycmd.Parameters.AddWithValue("@canshu1", \u201d[sssd]\u201c); \u8fd9\u6837\u5c31\u628a[sssd]\u6362\u5230\u4ee5\u524d\u7684\u8bed\u53e5\u91cc\u4e86 \uff0c\u8fd9\u79cd\u65b9\u5f0f\u53ef\u4ee5\u907f\u514d\u65b9\u62ec\u53f7\uff0c\u5355\u5f15\u53f7\u7b49\u654f\u611f\u5b57\u7b26
(select xxx from table b where a.sno=b.sno)是作为一个独立的显示的，你可以把它假设为out_name
即out_name是select xxx from table b where a.sno=b.sno;
总的是：select a.sno,out_name from table a；可以理解为先select xxx from table b where a.sno=b.sno,把它的结果和a.sno一起显示
select a.sno,a.sname from (select xxx from table x)里面,
把select xxx from table x查询的结果作为你个表（设为a_table），然后select a.sno,a.sname from a_table
select a.sno,
(select xxx from table b where a.sno=b.sno)
from table a
--其实就是一个字段而已 上面的等同于下面的
select a.sno
xxx
From table a,table b
Where a.sno=b.sno
--第二个
select a.sno,
a.sname
from (select xxx from table x)b
--也就是把select xxx from table x得到的结果作为一个表,记为b
--然后从b表里查询数据
1.
select a.sno,(select xxx from table b where a.sno=b.sno) from table a
这相当于一种连接方式，解析如下，a表等值连接b表
select a.sno,b.xxx from table a,table b where a.sno=b.sno;
2.
select a.sno,a.sname from (select xxx from table x)
这是一种子查询方式，解析：当直接从表里取数据时，不能得到想要的结果，就需要子查询来实现，把 (select xxx from table x)当做一个表来看
select a.sno,a.sname from (select xxx from table x) a
第一个主查A表，但是需要B表中个别字段
第二个先查询X表获取一张新表，在对新表查询。
明白？
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