① sql 条件只选择一个
如果是 SQL Server 或 Access：
select top 1 ...
如果是 MySql：
select ... limit 1
② 求一SQL选择语句
是要分别取6的前四条，7的前四条么？什么数据库？以下是sql server 05及以上版本取前2写法
declare @t table (ID varchar(10), CX varchar(10), CY varchar(10), Npts varchar(10), Pts varchar(10), Age varchar(10))
insert into @t
SELECT '959', '3016', '1430', '36', '23', '6' union all
SELECT '960', '3023', '1422', '24', '14', '6' union all
SELECT '950', '3013', '1419', '59', '37', '8' union all
SELECT '962', '3026', '1419', '24', '14', '6' union all
SELECT '1181', '3037', '1443', '109', '84', '7' union all
SELECT '949', '3010', '1423', '76', '52', '7' union all
SELECT '950', '3013', '1419', '59', '37', '7'
SELECT id,cx,cy,npts,pts,age from (
SELECT id,cx,cy,npts,pts,age,row_number() over (partition by age order by pts) as o
from @t
where age in ('6','7')
) as c
where c.o < 3
(7 行受影响)
id cx cy npts pts age
---------- ---------- ---------- ---------- ---------- ----------
960 3023 1422 24 14 6
962 3026 1419 24 14 6
950 3013 1419 59 37 7
949 3010 1423 76 52 7
(4 行受影响)
③ sql中的怎么选择数据
要效率建议给table1.项目建立个索引，想必table1.id 和 table2.id一定全是主键了，如果不是建立吧
语句上基本没有什么好优化的了
④ 急,SQL选择语句
sql="select * from anli where Elite=True or Elite=False order by Elite,ID desc"
或
sql="select * from anli where Elite=True or Elite=False order by Elite asc,ID desc"
⑤ SQL 选择查询
select * from 表名 order by 入学时间(时间格式） asc
⑥ sql选择语句
select id ,password into :idStr ,into :passwordStr from password where id = '1001'
⑦ SQL选择语句一个
left join $wpdb->postmeta meta_b on meta_a.post_id=meta_b.post_id
⑧ sql 选择语句 问题
用 in 表示 字符串是否存在字符串行表中；
（还有 not in)
sql="select top 28 *from data where n_class in ('农业','教育','慈善','新闻','健康','环保','地方','西部','扶贫','活动','城市','视频') order by n_id desc"
set rs=server.createobject("adodb.recordset")
//注意要加引号
⑨ SQL选择语句
1、
selectcount(1)blogs_cntfromblogs.websitegroupbyuserid
2、
selectcount(distinctuserid)fromBLOGS.ROLLERUSERa
whereexists(select1fromBLOGS.WEBSITEbwhereb.userid=a.userid)
selectcount(distinctuserid)fromBLOGS.ROLLERUSERa
wherenotexists(select1fromBLOGS.WEBSITEbwhereb.userid=a.userid)