ssql="select * from 123 where user_name='"&user_name&"' and user_password ='"&user_password&"'"能详细说明每个引号的意思吗?

ssql=select * from 123 where user_name='&user_name&' and user_password ='&user_password&'能详细说明每个引号的意思吗? select * from (select a.*,rownum aa from table a ) where aa=10 select * from book limit , String strSQL = SELECT * FROM Login +WHERE XM= ' + Login + '; 请问sql=select * from 招聘信息 order by id sql=select * from x where Min>2 and max oracle 子查询:select *,(select account from t_ps_member m where m.mid = po.mid) account from t_ps select c.*,d* from ( select 图号 from ( SELECT a.*,b.存货编码 FROM 未明图号 as a left OUTER JOIN 存select c.*,d* from ( select 图号 from (SELECT a.*,b.存货编码FROM 未明图号 as a left OUTER JOIN 存货档案 as bON a.图号=b.规 select * from a union select * from b 能详细说下么 select from 表 和select from [表]有什么不同? select count(*) from 怎么使用 select count(1) from emp select * into dept2 from dept 这个能合并成一句吗?select count(ITEMKIND) from ITEM where ITEMKIND='1' ; select count(ITEMKIND) from ITEM where ITEMKIND='2 ;select count(ITEMKIND) from ITEM where ITEMKIND='3' ;select count(ITEMKIND) from ITEM where ITEMKIND='4' ; select co 这句SQL语句是什么意思.ql=select distinct(selabel) from.sql=select distinct(selabel) from kcwl_labprosellog where isdel=0 &sqlfile& and selabel not in (select distinct(selabel) from kcwl_labprosell) 这个语句是什么作用的.说具 sql语句：去掉最大值,去掉最小值,算平均值SELECT AVG(Scores.Score)FROM ScoresWHERE ( ( (Scores.[ID]) = @id)AND (Score < (SELECT MAX(Score) From Scores WHERE Scores.[ID] = @id) )AND (Score > (SELECT MIN(Score) From Scores WHERE Scores.[I 列名acct_month ,acct_year,表名acct_vouch查询最大、小月,最小月要对应最小年select min(acct_month) as start_month from acct_vouch where acct_year=(select min(acct_year) from acct_vouch) select max(acct_month) as cur_month from acct_ 1' union select * from [ADM] union select *