<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8">
<meta name="generator" content="pdf2htmlEX">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<link rel="stylesheet" href="https://static.pudn.com/base/css/base.min.css">
<link rel="stylesheet" href="https://static.pudn.com/base/css/fancy.min.css">
<link rel="stylesheet" href="https://static.pudn.com/prod/directory_preview_static/62880c8816e0ca7141e6d23a/raw.css">
<script src="https://static.pudn.com/base/js/compatibility.min.js"></script>
<script src="https://static.pudn.com/base/js/pdf2htmlEX.min.js"></script>
<script>
try{
pdf2htmlEX.defaultViewer = new pdf2htmlEX.Viewer({});
}catch(e){}
</script>
<title></title>
</head>
<body>
<div id="sidebar" style="display: none">
<div id="outline">
</div>
</div>
<div id="pf1" class="pf w0 h0" data-page-no="1"><div class="pc pc1 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/62880c8816e0ca7141e6d23a/bg1.jpg"><div class="c x0 y1 w2 h2"><div class="t m0 x1 h3 y2 ff1 fs0 fc0 sc0 ls0 ws0">SQL</div><div class="t m0 x2 h3 y3 ff1 fs0 fc1 sc0 ls0 ws0">SQL</div><div class="t m0 x3 h4 y4 ff2 fs0 fc0 sc0 ls0 ws0">语言基础</div><div class="t m0 x4 h4 y3 ff2 fs0 fc1 sc0 ls0 ws0">语言基础</div><div class="t m0 x5 h5 y5 ff2 fs1 fc0 sc0 ls0 ws0">查询语句</div><div class="t m0 x6 h5 y6 ff2 fs1 fc1 sc0 ls0 ws0">查询语句</div></div></div><div class="pi" data-data='{"ctm":[1.333333,0.000000,0.000000,1.333333,0.000000,0.000000]}'></div></div>
</body>
</html>
<div id="pf2" class="pf w0 h0" data-page-no="2"><div class="pc pc2 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/62880c8816e0ca7141e6d23a/bg2.jpg"><div class="c x0 y1 w2 h2"><div class="t m0 x7 h4 y7 ff2 fs0 fc0 sc0 ls0 ws0">主要内容</div><div class="t m0 x8 h4 y8 ff2 fs0 fc1 sc0 ls0 ws0">主要内容</div><div class="t m0 x8 h6 y9 ff1 fs2 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 h7 ya ff1 fs1 fc0 sc0 ls0 ws0">SQL</div><div class="t m0 xa h7 yb ff1 fs1 fc1 sc0 ls0 ws0">SQL</div><div class="t m0 xb h5 yc ff2 fs1 fc0 sc0 ls0 ws0">查询语句语法</div><div class="t m0 xc h5 yb ff2 fs1 fc1 sc0 ls0 ws0">查询语句语法</div><div class="t m0 x8 h6 yd ff1 fs2 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 h5 ye ff2 fs1 fc0 sc0 ls0 ws0">简单查询</div><div class="t m0 xa h5 yf ff2 fs1 fc1 sc0 ls0 ws0">简单查询</div><div class="t m0 x8 h6 y10 ff1 fs2 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 h5 y11 ff2 fs1 fc0 sc0 ls0 ws0">连接查询</div><div class="t m0 xa h5 y12 ff2 fs1 fc1 sc0 ls0 ws0">连接查询</div><div class="t m0 x8 h6 y13 ff1 fs2 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 h5 y14 ff2 fs1 fc0 sc0 ls0 ws0">嵌套查询</div><div class="t m0 xa h5 y15 ff2 fs1 fc1 sc0 ls0 ws0">嵌套查询</div><div class="t m0 x8 h6 y16 ff1 fs2 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 h5 y17 ff2 fs1 fc0 sc0 ls0 ws0">使用库函数</div><div class="t m0 xa h5 y18 ff2 fs1 fc1 sc0 ls0 ws0">使用库函数</div><div class="t m0 x8 h6 y19 ff1 fs2 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 h5 y1a ff2 fs1 fc0 sc0 ls0 ws0">集合运算</div><div class="t m0 xa h5 y1b ff2 fs1 fc1 sc0 ls0 ws0">集合运算</div></div></div><div class="pi" data-data='{"ctm":[1.333333,0.000000,0.000000,1.333333,0.000000,0.000000]}'></div></div>
<div id="pf3" class="pf w0 h0" data-page-no="3"><div class="pc pc3 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/62880c8816e0ca7141e6d23a/bg3.jpg"><div class="c x0 y1 w2 h2"><div class="t m0 x7 h3 y1c ff1 fs0 fc0 sc0 ls0 ws0">SQL</div><div class="t m0 x8 h3 y8 ff1 fs0 fc1 sc0 ls0 ws0">SQL</div><div class="t m0 xb h4 y7 ff2 fs0 fc0 sc0 ls0 ws0">查询语句语法</div><div class="t m0 xc h4 y8 ff2 fs0 fc1 sc0 ls0 ws0">查询语句语法</div><div class="t m0 x8 h8 y1d ff1 fs3 fc2 sc0 ls0 ws0">•</div><div class="t m0 xd h9 y1e ff1 fs4 fc0 sc0 ls0 ws0">SELECT </div><div class="t m0 xe h9 y1f ff1 fs4 fc1 sc0 ls0 ws0">SELECT </div><div class="t m0 xf ha y20 ff2 fs4 fc0 sc0 ls0 ws0">查询目标</div><div class="t m0 x10 ha y1f ff2 fs4 fc1 sc0 ls0 ws0">查询目标</div><div class="t m0 x8 h8 y21 ff1 fs3 fc2 sc0 ls0 ws0">•</div><div class="t m0 xd h9 y22 ff1 fs4 fc0 sc0 ls0 ws0">FROM </div><div class="t m0 xe h9 y23 ff1 fs4 fc1 sc0 ls0 ws0">FROM </div><div class="t m0 x11 ha y24 ff2 fs4 fc0 sc0 ls0 ws0">数据库</div><div class="t m0 x12 ha y23 ff2 fs4 fc1 sc0 ls0 ws0">数据库</div><div class="t m0 x2 ha y24 ff2 fs4 fc0 sc0 ls0 ws0">1</div><div class="t m0 x2 ha y23 ff2 fs4 fc1 sc0 ls0 ws0">1</div><div class="t m0 x13 ha y24 ff2 fs4 fc0 sc0 ls0 ws0">，数据库</div><div class="t m0 x14 ha y23 ff2 fs4 fc1 sc0 ls0 ws0">，数据库</div><div class="t m0 x15 ha y24 ff2 fs4 fc0 sc0 ls0 ws0">2</div><div class="t m0 x16 ha y23 ff2 fs4 fc1 sc0 ls0 ws0">2</div><div class="t m0 x17 ha y22 ff2 fs4 fc0 sc0 ls0 ws0">，</div><div class="t m0 x18 ha y23 ff2 fs4 fc1 sc0 ls0 ws0">，</div><div class="t m0 x19 h9 y22 ff1 fs4 fc0 sc0 ls0 ws0">…</div><div class="t m0 x1a h9 y23 ff1 fs4 fc1 sc0 ls0 ws0">…</div><div class="t m0 x8 h8 y25 ff1 fs3 fc2 sc0 ls0 ws0">•</div><div class="t m0 xd h9 y26 ff1 fs4 fc0 sc0 ls0 ws0">[WHERE </div><div class="t m0 xe h9 y27 ff1 fs4 fc1 sc0 ls0 ws0">[WHERE </div><div class="t m0 x1b ha y28 ff2 fs4 fc0 sc0 ls0 ws0">条件表达式</div><div class="t m0 x1c ha y27 ff2 fs4 fc1 sc0 ls0 ws0">条件表达式</div><div class="t m0 x1d h9 y26 ff1 fs4 fc0 sc0 ls0 ws0">]</div><div class="t m0 x1e h9 y27 ff1 fs4 fc1 sc0 ls0 ws0">]</div><div class="t m0 x8 h8 y29 ff1 fs3 fc2 sc0 ls0 ws0">•</div><div class="t m0 xd h9 y2a ff1 fs4 fc0 sc0 ls0 ws0">[GROUP BY </div><div class="t m0 xe h9 y2b ff1 fs4 fc1 sc0 ls0 ws0">[GROUP BY </div><div class="t m0 x1f ha y2c ff2 fs4 fc0 sc0 ls0 ws0">分组列名 </div><div class="t m0 x20 ha y2b ff2 fs4 fc1 sc0 ls0 ws0">分组列名 </div><div class="t m0 x21 h9 y2a ff1 fs4 fc0 sc0 ls0 ws0">[HAVING [</div><div class="t m0 x22 h9 y2b ff1 fs4 fc1 sc0 ls0 ws0">[HAVING [</div><div class="t m0 x23 ha y2c ff2 fs4 fc0 sc0 ls0 ws0">组选择条件表达式</div><div class="t m0 x24 ha y2b ff2 fs4 fc1 sc0 ls0 ws0">组选择条件表达式</div><div class="t m0 x25 h9 y2a ff1 fs4 fc0 sc0 ls0 ws0">]]]</div><div class="t m0 x26 h9 y2b ff1 fs4 fc1 sc0 ls0 ws0">]]]</div><div class="t m0 x8 h8 y2d ff1 fs3 fc2 sc0 ls0 ws0">•</div><div class="t m0 xd h9 y2e ff1 fs4 fc0 sc0 ls0 ws0">[ORDER BY </div><div class="t m0 xe h9 y2f ff1 fs4 fc1 sc0 ls0 ws0">[ORDER BY </div><div class="t m0 x20 ha y30 ff2 fs4 fc0 sc0 ls0 ws0">排序项 </div><div class="t m0 x20 ha y2f ff2 fs4 fc1 sc0 ls0 ws0">排序项 </div><div class="t m0 x27 ha y30 ff2 fs4 fc0 sc0 ls0 ws0">[</div><div class="t m0 x28 ha y2f ff2 fs4 fc1 sc0 ls0 ws0">[</div><div class="t m0 x6 ha y2e ff2 fs4 fc0 sc0 ls0 ws0">序</div><div class="t m0 x29 ha y2f ff2 fs4 fc1 sc0 ls0 ws0">序</div><div class="t m0 x2a h9 y2e ff1 fs4 fc0 sc0 ls0 ws0">]</div><div class="t m0 x4 h9 y2f ff1 fs4 fc1 sc0 ls0 ws0">]</div><div class="t m0 x2b hb y2e ff3 fs4 fc0 sc0 ls0 ws0">…</div><div class="t m0 x2c hb y2f ff3 fs4 fc1 sc0 ls0 ws0">…</div><div class="t m0 x18 h9 y2e ff1 fs4 fc0 sc0 ls0 ws0">];</div><div class="t m0 x2d h9 y2f ff1 fs4 fc1 sc0 ls0 ws0">];</div><div class="t m0 x8 h8 y31 ff1 fs3 fc2 sc0 ls0 ws0">•</div><div class="t m0 xd ha y32 ff2 fs4 fc0 sc0 ls0 ws0">其中查询目标可以用下列格式<span class="_ _0"></span>表示：</div><div class="t m0 xe ha y33 ff2 fs4 fc1 sc0 ls0 ws0">其中查询目标可以用下列格式<span class="_ _0"></span>表示：</div><div class="t m0 x8 h8 y34 ff1 fs3 fc2 sc0 ls0 ws0">•</div><div class="t m0 xd ha y35 ff2 fs4 fc0 sc0 ls0 ws0">　　</div><div class="t m0 xe ha y36 ff2 fs4 fc1 sc0 ls0 ws0">　　</div><div class="t m0 x2e h9 y37 ff1 fs4 fc0 sc0 ls0 ws0">[ALL|DISTINCT][</div><div class="t m0 x2f h9 y36 ff1 fs4 fc1 sc0 ls0 ws0">[ALL|DISTINCT][</div><div class="t m0 x30 ha y35 ff2 fs4 fc0 sc0 ls0 ws0">别名</div><div class="t m0 x5 ha y36 ff2 fs4 fc1 sc0 ls0 ws0">别名</div><div class="t m0 x31 h9 y37 ff1 fs4 fc0 sc0 ls0 ws0">.]<</div><div class="t m0 x32 h9 y36 ff1 fs4 fc1 sc0 ls0 ws0">.]<</div><div class="t m0 x33 ha y35 ff2 fs4 fc0 sc0 ls0 ws0">表达式</div><div class="t m0 x34 ha y36 ff2 fs4 fc1 sc0 ls0 ws0">表达式</div><div class="t m0 x35 h9 y37 ff1 fs4 fc0 sc0 ls0 ws0">>[,<</div><div class="t m0 x36 h9 y36 ff1 fs4 fc1 sc0 ls0 ws0">>[,<</div><div class="t m0 x37 ha y35 ff2 fs4 fc0 sc0 ls0 ws0">表达式</div><div class="t m0 x38 ha y36 ff2 fs4 fc1 sc0 ls0 ws0">表达式</div><div class="t m0 x39 h9 y37 ff1 fs4 fc0 sc0 ls0 ws0">>]</div><div class="t m0 x3a h9 y36 ff1 fs4 fc1 sc0 ls0 ws0">>]</div><div class="t m0 x3b hb y37 ff3 fs4 fc0 sc0 ls0 ws0">…</div><div class="t m0 x3c hb y36 ff3 fs4 fc1 sc0 ls0 ws0">…</div><div class="t m0 x8 h8 y38 ff1 fs3 fc2 sc0 ls0 ws0">•</div><div class="t m0 xd ha y39 ff2 fs4 fc0 sc0 ls0 ws0">表达式可以是由属性、库函数<span class="_ _0"></span>和常量用算术运算符组成的公式</div><div class="t m0 xe ha y3a ff2 fs4 fc1 sc0 ls0 ws0">表达式可以是由属性、库函数<span class="_ _0"></span>和常量用算术运算符组成的公式</div></div></div><div class="pi" data-data='{"ctm":[1.333333,0.000000,0.000000,1.333333,0.000000,0.000000]}'></div></div>
<div id="pf4" class="pf w0 h0" data-page-no="4"><div class="pc pc4 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/62880c8816e0ca7141e6d23a/bg4.jpg"><div class="c x0 y1 w2 h2"><div class="t m0 x7 h4 y7 ff2 fs0 fc0 sc0 ls0 ws0">语法说明</div><div class="t m0 x8 h4 y8 ff2 fs0 fc1 sc0 ls0 ws0">语法说明</div><div class="t m0 x8 hc y3b ff1 fs5 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 hd y3c ff1 fs6 fc0 sc0 ls0 ws0">SELECT<span class="_ _1"></span> [ALL | DISTINCT] c<span class="_ _1"></span>olumn1[,colum<span class="_ _1"></span>n2]</div><div class="t m0 xa hd y3d ff1 fs6 fc1 sc0 ls0 ws0">SELECT<span class="_ _1"></span> [ALL | DISTINCT] c<span class="_ _1"></span>olumn1[,colum<span class="_ _1"></span>n2]</div><div class="t m0 x8 hc y3e ff1 fs5 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 hd y3f ff1 fs6 fc0 sc0 ls0 ws0">FROM table1[,table2]</div><div class="t m0 xa hd y40 ff1 fs6 fc1 sc0 ls0 ws0">FROM table1[,table2]</div><div class="t m0 x8 hc y41 ff1 fs5 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 hd y42 ff1 fs6 fc0 sc0 ls0 ws0">[WHERE<span class="_ _1"></span> <conditions>]</div><div class="t m0 xa hd y43 ff1 fs6 fc1 sc0 ls0 ws0">[WHERE<span class="_ _1"></span> <conditions>]</div><div class="t m0 x8 hc y44 ff1 fs5 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 hd y45 ff1 fs6 fc0 sc0 ls0 ws0">[GROUP BY <<span class="_ _1"></span>column-list>]</div><div class="t m0 xa hd y46 ff1 fs6 fc1 sc0 ls0 ws0">[GROUP BY <<span class="_ _1"></span>column-list>]</div><div class="t m0 x8 hc y47 ff1 fs5 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 hd y48 ff1 fs6 fc0 sc0 ls0 ws0">[HAVING <conditions><span class="_ _1"></span>]</div><div class="t m0 xa hd y49 ff1 fs6 fc1 sc0 ls0 ws0">[HAVING <conditions><span class="_ _1"></span>]</div><div class="t m0 x8 hc y4a ff1 fs5 fc2 sc0 ls0 ws0">•</div><div class="t m0 x9 hd y2e ff1 fs6 fc0 sc0 ls0 ws0">[ORDER B<span class="_ _1"></span>Y <column-l<span class="_ _1"></span>ist> ][ASC | DE<span class="_ _1"></span>SC] ] ;</div><div class="t m0 xa hd y4b ff1 fs6 fc1 sc0 ls0 ws0">[ORDER B<span class="_ _1"></span>Y <column-l<span class="_ _1"></span>ist> ][ASC | DE<span class="_ _1"></span>SC] ] ;</div><div class="t m0 x3d hd y4c ff1 fs6 fc0 sc0 ls0 ws0">SELEC<span class="_ _1"></span>T [ALL|DISTINCT]<span class="_ _1"></span> <</div><div class="t m0 x8 hd y4d ff1 fs6 fc1 sc0 ls0 ws0">SELEC<span class="_ _1"></span>T [ALL|DISTINCT]<span class="_ _1"></span> <</div><div class="t m0 x3e he y4e ff2 fs6 fc0 sc0 ls0 ws0">目标列表达式</div><div class="t m0 x21 he y4d ff2 fs6 fc1 sc0 ls0 ws0">目标列表达式</div><div class="t m0 x3f hd y4c ff1 fs6 fc0 sc0 ls0 ws0">>[,<</div><div class="t m0 x40 hd y4d ff1 fs6 fc1 sc0 ls0 ws0">>[,<</div><div class="t m0 x41 he y4e ff2 fs6 fc0 sc0 ls0 ws0">目标列表达式</div><div class="t m0 x42 he y4d ff2 fs6 fc1 sc0 ls0 ws0">目标列表达式</div><div class="t m0 x43 hd y4c ff1 fs6 fc0 sc0 ls0 ws0">>]</div><div class="t m0 x44 hd y4d ff1 fs6 fc1 sc0 ls0 ws0">>]</div><div class="t m0 x45 hf y4c ff3 fs6 fc0 sc0 ls0 ws0">……</div><div class="t m0 x46 hf y4d ff3 fs6 fc1 sc0 ls0 ws0">……</div><div class="t m0 x3d hd y4f ff1 fs6 fc0 sc0 ls0 ws0"> </div><div class="t m0 x8 hd y50 ff1 fs6 fc1 sc0 ls0 ws0"> </div><div class="t m0 x47 hd y4f ff1 fs6 fc0 sc0 ls0 ws0">FROM <</div><div class="t m0 x48 hd y50 ff1 fs6 fc1 sc0 ls0 ws0">FROM <</div><div class="t m0 x49 he y51 ff2 fs6 fc0 sc0 ls0 ws0">表名或视图名</div><div class="t m0 x4a he y50 ff2 fs6 fc1 sc0 ls0 ws0">表名或视图名</div><div class="t m0 x29 hd y4f ff1 fs6 fc0 sc0 ls0 ws0">>[,<</div><div class="t m0 x4b hd y50 ff1 fs6 fc1 sc0 ls0 ws0">>[,<</div><div class="t m0 x32 he y51 ff2 fs6 fc0 sc0 ls0 ws0">表名或视图名</div><div class="t m0 x4c he y50 ff2 fs6 fc1 sc0 ls0 ws0">表名或视图名</div><div class="t m0 x4d hd y4f ff1 fs6 fc0 sc0 ls0 ws0">>]</div><div class="t m0 x4e hd y50 ff1 fs6 fc1 sc0 ls0 ws0">>]</div><div class="t m0 x4f hf y4f ff3 fs6 fc0 sc0 ls0 ws0">……</div><div class="t m0 x50 hf y50 ff3 fs6 fc1 sc0 ls0 ws0">……</div><div class="t m0 x3d hd y52 ff1 fs6 fc0 sc0 ls0 ws0"> </div><div class="t m0 x8 hd y53 ff1 fs6 fc1 sc0 ls0 ws0"> </div><div class="t m0 x47 hd y52 ff1 fs6 fc0 sc0 ls0 ws0">[WHERE <</div><div class="t m0 x48 hd y53 ff1 fs6 fc1 sc0 ls0 ws0">[WHERE <</div><div class="t m0 x51 he y54 ff2 fs6 fc0 sc0 ls0 ws0">条件表达式</div><div class="t m0 x52 he y53 ff2 fs6 fc1 sc0 ls0 ws0">条件表达式</div><div class="t m0 x5 hd y52 ff1 fs6 fc0 sc0 ls0 ws0">>]</div><div class="t m0 x6 hd y53 ff1 fs6 fc1 sc0 ls0 ws0">>]</div><div class="t m0 x3d hd y55 ff1 fs6 fc0 sc0 ls0 ws0"> </div><div class="t m0 x8 hd y56 ff1 fs6 fc1 sc0 ls0 ws0"> </div><div class="t m0 x47 hd y55 ff1 fs6 fc0 sc0 ls0 ws0">[GROUP BY <</div><div class="t m0 x48 hd y56 ff1 fs6 fc1 sc0 ls0 ws0">[GROUP BY <</div><div class="t m0 x2 he y57 ff2 fs6 fc0 sc0 ls0 ws0">列名</div><div class="t m0 x53 he y56 ff2 fs6 fc1 sc0 ls0 ws0">列名</div><div class="t m0 x54 hd y55 ff1 fs6 fc0 sc0 ls0 ws0">1> [HAVING <</div><div class="t m0 x55 hd y56 ff1 fs6 fc1 sc0 ls0 ws0">1> [HAVING <</div><div class="t m0 x56 he y57 ff2 fs6 fc0 sc0 ls0 ws0">条件表达式</div><div class="t m0 x57 he y56 ff2 fs6 fc1 sc0 ls0 ws0">条件表达式</div><div class="t m0 x58 hd y55 ff1 fs6 fc0 sc0 ls0 ws0">>]]</div><div class="t m0 x59 hd y56 ff1 fs6 fc1 sc0 ls0 ws0">>]]</div><div class="t m0 x3d hd y58 ff1 fs6 fc0 sc0 ls0 ws0"> </div><div class="t m0 x8 hd y59 ff1 fs6 fc1 sc0 ls0 ws0"> </div><div class="t m0 x47 hd y58 ff1 fs6 fc0 sc0 ls0 ws0">[ORDER</div><div class="t m0 x48 hd y59 ff1 fs6 fc1 sc0 ls0 ws0">[ORDER</div></div></div><div class="pi" data-data='{"ctm":[1.333333,0.000000,0.000000,1.333333,0.000000,0.000000]}'></div></div>
<div id="pf5" class="pf w0 h0" data-page-no="5"><div class="pc pc5 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/62880c8816e0ca7141e6d23a/bg5.jpg"><div class="c x0 y1 w2 h2"><div class="t m0 x7 h10 y1c ff4 fs0 fc0 sc0 ls0 ws0">SELECT</div><div class="t m0 x8 h10 y8 ff4 fs0 fc1 sc0 ls0 ws0">SELECT</div><div class="t m0 x5a h4 y7 ff2 fs0 fc0 sc0 ls0 ws0">语句的组件 </div><div class="t m0 x5b h4 y8 ff2 fs0 fc1 sc0 ls0 ws0">语句的组件 </div><div class="t m0 x2e h11 y5a ff2 fs7 fc1 sc0 ls0 ws0">组 件<span class="_ _2"> </span>说 明</div><div class="t m0 x8 h11 y5b ff5 fs7 fc1 sc0 ls0 ws0">SELECT<span class="_ _3"> </span><span class="ff2">指明要检索的数据的列</span></div><div class="t m0 x8 h11 y5c ff5 fs7 fc1 sc0 ls0 ws0">FROM<span class="_ _4"> </span><span class="ff2">指明从哪（几）个表中进行检索</span></div><div class="t m0 x8 h11 y5d ff5 fs7 fc1 sc0 ls0 ws0">WHERE<span class="_ _5"> </span><span class="ff2">指明返回数据必须满足的条件</span></div><div class="t m0 x8 h11 y5e ff5 fs7 fc1 sc0 ls0 ws0">GROUP BY<span class="_ _6"> </span><span class="ff2">指明返回的列数据通过某些条件来形成组</span></div><div class="t m0 x8 h11 y5f ff5 fs7 fc1 sc0 ls0 ws0">HAVING<span class="_ _7"> </span><span class="ff2">指明返回的集合必须满足的条件</span></div><div class="t m0 x8 h11 y60 ff5 fs7 fc1 sc0 ls0 ws0">ORDER BY<span class="_ _6"> </span><span class="ff2">指明返回的行的排序顺序</span></div></div></div><div class="pi" data-data='{"ctm":[1.333333,0.000000,0.000000,1.333333,0.000000,0.000000]}'></div></div>
