g1 E8 `9 e/ v5 o 9 |$ o D1 e) X0 M6 D
Rasmussen # C' ?4 q: f3 s
8 B1 K; X; p) h2 F. K) p- H . R' T6 G7 Y- r0 F: I& x . g. _8 m+ g; u! N { Storgt 67 - I3 @8 T# A. K; U : p: Y. p% O( m0 T2 e& B2 h
! c, k; x3 T% p+ x+ f. L
- R. s$ V! k" v/ I/ s& ?5 u4 G# C" a0 a </P><>运行下面的SQL将Person表中LastName字段为"Rasmussen"的FirstName更新为"Nina":</P><>UPDATE Person SET FirstName = 'Nina' ; `" |5 A. `1 D
WHERE LastName = 'Rasmussen' ) o1 G* y7 x9 Q. w; d( Y 8 X, |; A% u y3 r8 u( {5 i$ q
更新后"erson"表中的数据为: m& v, D) U8 \; {- A
</P><>LastName ( o6 V2 p1 U e ! B1 o1 V7 f0 `4 @0 Y P: b( M
FirstName 3 E) _$ j: `2 u5 b& N l
/ r! \9 D2 w5 s3 z' h# y Address 9 d4 m6 T4 K. ~* Z3 ?2 ~4 z+ X 3 `# _: H( B& @
City 6 l7 q9 S' k* d
0 D' v8 N& a5 W: W' ]- w. I
: \3 q: K3 [" q6 x/ iNilsen 5 f# U5 s% I; y: H/ A s
) @1 a5 F! ? b# x" D
Fred 9 D* \' X+ S2 r! }& z
$ [0 J# [9 q/ h
Kirkegt 56 ; G/ X+ d$ Z W" H4 |
. F/ D5 ?1 y* i4 c- g
Stavanger ' M# P5 Q) Z( w % N$ J* _) Z$ j& a0 E 1 i4 `, `) n4 p- |; C) L
Rasmussen 4 Y) k3 i! y s2 D8 q 6 P0 C* r) |- L+ d2 _' | Nina - M% |) S+ M9 \- N+ J4 ]' Q ! Y" G L7 S) B/ e' k+ z Storgt 67 , U& `# j0 `; L) Q 4 y) E3 |+ _- ]+ ^; l$ M
& {/ k) P4 o; w3 C
/ s& G5 h3 l& k u) g! |
</P><>同样的,用UPDATE语句也可以同时更新多个字段:</P><>UPDATE Person ' H. e4 _: ]- F( t/ f( {SET Address = 'Stien 12', City = 'Stavanger' ; ^( f$ X/ p, W# G( N
WHERE LastName = 'Rasmussen' # B; y5 f: l% L& a& O
</P><>更新后"erson"表中的数据为:</P><>LastName . l- L) V# b C
3 Q- l8 m$ t3 @+ P
FirstName " T6 ]5 w) N+ w; U3 w% f: N
6 Y9 F* a6 c, H E& E5 \ Address 8 Q" L9 T' E. T& w3 h
7 P( c6 i0 O) S' D$ r City ' E7 M5 ^ ~6 r! G! G$ F+ _ 1 M a# s5 s! \1 l, n 5 T9 r* N) d: O- \) T
Nilsen 2 M9 v. u+ T, }( r* j0 `5 n 3 E& t' W& g( \% x! H) K6 J Fred & d& |9 z+ ^7 Y1 H
% m* o! R; g, b0 ?2 l9 R7 L/ w6 u Kirkegt 56 ! ^. ~& S) _3 R& b
9 @ u2 ^$ \7 b
Stavanger O7 ]' u; N! \. A* J5 b+ R- H% o
, {2 h, K+ K& q) m# a. U/ A ! V: {' h8 U7 d5 }$ r
Rasmussen 7 i0 C( l3 H* a* J
3 w; X& N! M4 K& ~" O. Q. a* Z Nina 9 Q3 u6 D$ o% Y5 r: J4 j8 y: r
9 Z# `' ]/ T# P Stien 12 ( ~ Z- q3 r; `2 u
( G+ n% n7 d6 m1 M( p2 r! J4 M Stavanger 4 W% g) r0 T& o J
</P>
<>Create Table5 [( y, u$ L, N: x! j' C- F
用途: * U( I+ o' ]3 @0 ~ </P><> 建立新的资料表。</P><>语法: 4 S: r; I; D9 v" Y$ U" |' R
</P><>CREATE TABLE table_name W4 q" I" V1 z9 n/ V( 0 }1 R3 R" H2 C0 ~, [column_name1 data_type, 4 A3 O% l) ]3 W& F# k. }: d2 Q' L
column_name2 data_type, & Z. f. n+ ~1 y2 e" N! q0 m
....... 1 x) i: H1 T" P5 t" T- L( V
) ) y! f( w+ b1 |6 B- s7 h2 r ' F- ]5 ?$ g8 Y5 s$ ?+ p" k( E例: H: \' f( V% u* y. {& l) d" m </P><>创建一张叫"erson"的表,该表有4个字段"LastName", "FirstName", "Address", "Age": 3 Y _1 L7 h! A/ | </P><>CREATE TABLE Person 9 c2 Y: J/ L2 P* B R7 b( 8 X! O8 u/ W* g/ M
LastName varchar, ! s1 }! `& m+ F/ s- g
FirstName varchar, " Z0 `) Y, L' f( MAddress varchar, ' M7 k! T7 v0 k! T- gAge int & T) k" Y+ S- g; y) 2 `5 c# G- j# W' I
</P><>如果想指定字段的最大存储长度,你可以这样:</P><>CREATE TABLE Person 5 R K" U G0 c+ B! s& @
( 4 b- r& A! v1 V2 F/ a, u
LastName varchar(30), % P+ N+ M/ b& y2 f3 I) f
FirstName varchar(30), 5 C8 s6 }7 G' @+ P ]Address varchar(120), 8 L" J- c; k: _Age int(3) , i0 z; H( B& Z: V" X
) 4 W0 A' l" c" G9 {% p </P><>下表中列出了在SQL的一些数据类型:</P><>Data Type ; F- V/ Y8 U1 _ l' v: r3 N
4 F% M: ~2 m% k0 ^4 M2 h. Z* [
Description * e' n2 @) I; O 8 i! M( P. B/ f* {6 [ 4 D/ P, h! D2 V0 Hinteger(size)5 V L4 v8 O8 f# L0 E! @6 {
int(size) 0 [9 P% r5 {; R3 u% u- w; Lsmallint(size)1 X* Y+ k3 f1 `
tinyint(size) 3 B3 [0 d e2 {# e- k- O
7 s% `& \: t* e4 k& ~
Hold integers only. The maximum number of digits are specified in parenthesis. / v! K0 S+ `1 v# C; B' b# N. H 4 e0 B9 m; [8 n: A2 N4 ?+ ~0 Z4 [; k3 J
; b3 u2 @9 L2 Y, j" ?# d' u* P5 e2 F- x
decimal(size,d) 4 X' W% {, K+ znumeric(size,d) ( i+ j: W$ r' [& O p+ J
5 N9 ]# \$ n% o) R H1 k" C Hold numbers with fractions. The maximum number of digits are specified in "size". The maximum number of digits to the right of the decimal is specified in "d". 9 b3 Y2 o: h: N7 F6 d
0 b$ r$ i8 d2 K( c( N2 H & O; Y# U6 G; _2 q; w, G
char(size) ; n2 F. D) x, |+ f
; E# r5 I ]+ A" u' \# `
Holds a fixed length string (can contain letters, numbers, and special characters). The fixed size is specified in parenthesis. ( Q4 v7 m! t) T9 Y2 a, ?5 j
/ N8 n/ C! X; ~# `* S( \
7 ]" \# F* F8 }0 T8 L6 S% p1 u" K Holds a variable length string (can contain letters, numbers, and special characters). The maximum size is specified in parenthesis. ( j% @4 @( K5 u, s. ?
+ b8 f. k7 c R
: |4 _, P V% G" \/ L
date(yyyymmdd) 3 A/ g% R0 g+ N7 \ $ H% h3 `& ]) t3 m Holds a date 3 g& m1 @- \; ^4 j7 Q$ v) r3 C: J
4 G' k8 _- O: m1 D' o
/ \5 E& V. X+ H, z4 V
5 \# f4 O9 N) E& H! O* | </P><>在Person表中增加一个名为City的字段:</P><>ALTER TABLE Person ADD City varchar(30) " \5 f" [; K: C
</P><>增加后表中数据如下:</P><>LastName 4 W, ^( o7 j. H" g9 Z# c( r
# [; A; D& k* q% p! J u9 v
FirstName 4 L, i" @$ k0 ^, O
; Z" _3 h! \' N- \
Address 4 n/ I9 R I2 m$ h* c8 f$ j$ y' b4 Y # X( B: U, W; g- t8 Q. R; ~
City " W, C, S4 c' G2 I2 r* k5 H( s7 m0 \ ' b2 k$ m/ G. J; _; E * W* ~: B! e+ q& r! ~" k9 S, Q
Pettersen ) Y M& L) E7 i6 Q
% F( C: J9 K) |1 f9 F4 c% `( W Kari z: k5 f9 Z8 V8 b9 H2 ~
8 |: v# M. N2 O5 I9 y Storgt 20 & r8 }5 `8 ~- R0 t) g$ M* }
! E/ l5 p$ v, b( W% ~3 f8 i
' V8 ~8 r) K: |. C3 n
/ g, f* ~) p6 E7 A& k
! [* E% }7 Y) H( g
2 w8 {% `5 `) z K9 B6 q# c# N </P><>移除Person表中原有的Address字段:</P><>ALTER TABLE Person DROP COLUMN Address ! L8 ]1 }3 h+ }7 B5 p' [: g: E
</P><>移除后表中数据如下:</P><>LastName * K/ G3 ?$ B8 [+ T
( P( T7 b$ `4 X FirstName & j# u& |8 E4 Y& @+ H ( Y5 [, W \0 Z. W5 z
City 0 M# A3 m5 l e' n! h & [ d+ n: g, k0 M8 ] + G/ Y3 k8 q, e/ U- e* o gPettersen 7 \9 ~! {$ r, y" E2 A- O5 N
: r* S# _9 s* A" W Kari % v* A% M. v- u; h/ l
</P>
<>max $ a2 |! m8 I o8 _( t' C& `用途: # o' T; F4 N- ?& T% R+ X& Q* b; u </P><> 传回选取的结果集中值的最大值。已忽略 Null 值。 . v; O. R' _9 n+ c9 ]( a/ O
</P><>语法: $ H8 Q# D" F: _: s( M </P><>SELECT MAX(column_name) FROM table_name ; H9 |" J ~0 ?
</P><>例:</P><>"ersons"表中原始数据如下:</P><>Name 0 Z, g2 ^9 u6 v B7 h ( m1 E C% ^1 E, h3 N
Age 4 s, i* y0 A' K. E# O 6 ?$ }; H: f8 M; b+ W3 A # N8 e; x- ~% Q: h1 }9 ]1 aHansen, Ola 9 ]) T2 k; B( x. ]
& K% u k7 Y. }0 z) x
34 G5 j! E* [# _ 1 `; H6 K0 a' B6 u - X! U/ _3 G! z) I% a" [Svendson, Tove - W2 v3 l; j x- A% f4 g ; X9 H d! x. m6 |! v- \8 M7 \$ g
45 " V8 d" K% ]8 U
Z' f' U, A1 D$ ^" g5 K* }
; P* w6 j9 B) Y! z- d" `, X
Pettersen, Kari , h/ t. P& {1 ]9 k$ t5 P6 v3 Y" R. d9 k
% y) d1 O0 \. ]! d ?. y& h 19 , |. l1 ?# I. U) R" A) L
2 s Q, \7 n8 a" ?1 W7 P 5 C8 F1 ~7 f x& m% M$ s; r. W
选取"ersons"表中的最大年龄: ; d6 H6 x" T# c
</P><>SELECT MAX(Age) FROM Persons ! L: M% Y# b1 s9 |- P' x </P><>执行结果:</P><>45 * @& m7 Y6 v/ i# }0 b7 ?4 X
5 M+ Z }7 n/ ]3 s+ u : x6 E0 ^& \. e, }+ V9 W </P><>min * M& f8 u* t' c B' r用途: , C, f* t8 C, H; I1 O1 F: a5 S
</P><> 传回选取的结果集中值的最小值。已忽略 Null 值。 1 E+ G! x1 A( p </P><>语法: $ n9 Y$ f" d: a& K7 x; n
</P><>SELECT MIN(column_name) FROM table_name 3 u3 ?: } T) U: y: P+ T5 B </P><>例:</P><>"ersons"表中原始数据如下:</P><>Name ) |' A( R( K0 Z% o7 [1 G . S8 ^) P! @/ \! \! d
Age ) c) u& {2 r/ H' w; X
; S7 h% Q7 t4 s* Y$ }. f( _
% e2 l0 D1 L t
Hansen, Ola - }# j4 X+ K1 t/ \0 P
. Z; ^! f c) r7 A( j
34 0 b1 [' b6 G" V2 o $ m/ n* X& X( G+ M1 D. o, |/ R# e
# p; F* d" P9 b. m( ]
Svendson, Tove 5 S n) ~5 o$ G# L9 A
$ [* S. A" m2 ?0 g 45 " r6 t4 L9 u; \( a- J$ q* Y ) u5 D/ d! C' L. D- o& {$ K$ L( P
, h/ @4 B$ n, t
Pettersen, Kari : q$ z9 U: {+ N$ B) J+ L " b6 d6 F* P* \, u& n
19 + T$ ]" {2 m+ _! y% H
9 F6 I0 D4 ~: K& ^9 q
' h8 L6 R" M8 I
选取"ersons"表中的最小年龄: & N; I; Q8 T' Y2 a
</P><>SELECT MIN(Age) FROM Persons 6 ~0 p. o; S$ ]& ]3 \9 L; w0 c" z </P><>执行结果:</P><>19 ! T/ O6 L( a! y8 b( R 3 V# P9 q" ]* T . U6 }2 v& Y( s: l* i4 | </P><> 2 [8 A8 x# [2 O' T. \. {& U8 ?
</P><> 8 O, ?" D+ E5 r' C- c# ^</P>