</p> 8、说明:创建索引:create [unique] index idxname on tabname(col….)8 ~' K" `' P7 A0 n. e
删除索引:drop index idxname
( H% U# O& P# o( x% g1 s$ r 注:索引是不可更改的,想更改必须删除重新建。
" [7 M j+ }# n+ n. J7 q1 |0 a 9、说明:创建视图:create view viewname as select statement
G7 r* K1 g5 Z9 m1 j 删除视图:drop view viewname: O* d3 a# p9 Z) z" o
10、说明:几个简单的基本的sql语句
5 s ], d9 }% o3 i) G, Q4 r 选择:select * from table1 where 范围- \- r9 @8 Z) Q+ w6 G4 I
插入:insert into table1(field1,field2) values(value1,value2)! J7 d9 g1 O d5 o6 j, V" u2 Z* _) Q
删除:delete from table1 where 范围9 Y* v. @# k3 X. {6 d: k
更新:update table1 set field1=value1 where 范围9 y) a* i8 n( ?. w# n
查找:select * from table1 where field1 like ’%value1%’ ---like的语法很精妙,查资料!" `, ?6 K) s" T
排序:select * from table1 order by field1,field2 [desc]
# i9 c7 O, p4 |- o3 j 总数:select count as totalcount from table1
" v9 [, |4 y) I' V; I- p 求和:select sum(field1) as sumvalue from table1
$ B6 @' i! E. o2 D& s 平均:select avg(field1) as avgvalue from table18 p+ W4 h0 G C, Q+ [" ^% F8 G' S+ ~% `
最大:select max(field1) as maxvalue from table1& k4 ~. t6 {' i: d
最小:select min(field1) as minvalue from table1 |