作者·2011-04-17 20:30

数据类型

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<DIV>分为两种类型：内置的数据类型和用户自定义的数据类型</DIV>
<DIV>内置类型包括数值型、文本型、日期时间型和XML四大类。</DIV>
<DIV><STRONG>数值型：</STRONG></DIV>
<DIV>
<TABLE style="WIDTH: 320pt; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=0 width=426 border=0>

<TBODY>
<TR style="HEIGHT: 13.5pt" height=18>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 54pt; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 13.5pt; BACKGROUND-COLOR: transparent" width=72 height=18><FONT face=宋体>类型</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 54pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=72><FONT face=宋体>名称</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 78pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=104><FONT face=宋体>简称</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 43pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=57><FONT face=宋体>字节数</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 91pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=121><FONT face=宋体>精确度</FONT></TD></TR>
<TR style="HEIGHT: 21pt; mso-height-source: userset" height=28>
<TD class=xl66 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext 0.5pt solid; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 48pt; BACKGROUND-COLOR: transparent" height=64 rowSpan=3><FONT face=宋体>整型</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>SMALLINT</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>小整型</FONT></TD>
<TD class=xl66 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>2</FONT></TD>
<TD class=xl66 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>5位</FONT></TD></TR>
<TR style="HEIGHT: 13.5pt" height=18>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 13.5pt; BACKGROUND-COLOR: transparent" height=18><FONT face=宋体>INT</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>整型</FONT></TD>
<TD class=xl66 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>4</FONT></TD>
<TD class=xl66 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>10位</FONT></TD></TR>
<TR style="HEIGHT: 13.5pt" height=18>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 13.5pt; BACKGROUND-COLOR: transparent" height=18><FONT face=宋体>BIGINT</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>大整型</FONT></TD>
<TD class=xl66 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>8</FONT></TD>
<TD class=xl66 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>19位</FONT></TD></TR>
<TR style="HEIGHT: 40.5pt; mso-height-source: userset" height=54>
<TD class=xl66 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext 0.5pt solid; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 96.75pt; BACKGROUND-COLOR: transparent" height=129 rowSpan=3><FONT face=宋体>浮点型</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>REAL</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>单精度浮点数</FONT></TD>
<TD class=xl67 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 134pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=178 colSpan=2><FONT face=宋体>实数的32位近似值，数字可以为零</FONT></TD></TR>
<TR style="HEIGHT: 27.75pt; mso-height-source: userset" height=37>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 27.75pt; BACKGROUND-COLOR: transparent" height=37><FONT face=宋体>DOUBLE</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>双精度浮点数</FONT></TD>
<TD class=xl67 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 134pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=178 colSpan=2><FONT face=宋体>实数的64位近似值，数字可以为零</FONT></TD></TR>
<TR style="HEIGHT: 28.5pt; mso-height-source: userset" height=38>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 28.5pt; BACKGROUND-COLOR: transparent" height=38><FONT face=宋体>DECFLOAT</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>十进制浮点数</FONT></TD>
<TD class=xl67 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 134pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=178 colSpan=2><FONT face=宋体>适合处理货币值，适合处理十进制浮点数</FONT></TD></TR>
<TR style="HEIGHT: 78pt; mso-height-source: userset" height=104>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext 0.5pt solid; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 78pt; BACKGROUND-COLOR: transparent" height=104><FONT face=宋体>十进制型</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>DECIMAL</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>十进制数</FONT></TD>
<TD class=xl67 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 134pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=178 colSpan=2><FONT face=宋体>可自定义小位位数的压缩型十进制数，也可写成DEC,NUMERIC,NUM，可写成DEC(p,s)，p为数字总长度，s表示小数长度</FONT></TD></TR></TBODY></TABLE></DIV>
<DIV> </DIV>
<DIV><STRONG>字符型：</STRONG></DIV>
<DIV>
<TABLE style="WIDTH: 561pt; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=0 width=748 border=0>

<TBODY>
<TR style="HEIGHT: 13.5pt" height=18>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 54pt; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 13.5pt; BACKGROUND-COLOR: transparent" width=72 height=18><FONT face=宋体>类型</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 83pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=111><FONT face=宋体>名称</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 87pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=116><FONT face=宋体>简称</FONT></TD>
<TD class=xl69 style="BORDER-RIGHT: black 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 222pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=296 colSpan=2><FONT face=宋体>长度</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 115pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=153><FONT face=宋体>备注</FONT></TD></TR>
<TR style="HEIGHT: 13.5pt" height=18>
<TD class=xl66 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext 0.5pt solid; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 107.25pt; BACKGROUND-COLOR: transparent" height=143 rowSpan=4><FONT face=宋体>单字节</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>char</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>长字符串</FONT></TD>
<TD class=xl69 style="BORDER-RIGHT: black 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" colSpan=2><FONT face=宋体>介于1到254字节之间,没指定为1个字节</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>　</FONT></TD></TR>
<TR style="HEIGHT: 42.75pt; mso-height-source: userset" height=57>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 42.75pt; BACKGROUND-COLOR: transparent" height=57><FONT face=宋体>varchar</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>变长字符串</FONT></TD>
<TD class=xl71 style="BORDER-RIGHT: black 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 222pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=296 colSpan=2><FONT face=宋体>需指定最大长度,最大32672,需额外用4个字节存储实际长度，如长度varchar(20)为20，则实际为20+4个字节的空间</FONT></TD>
<TD class=xl82 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; WIDTH: 115pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=153><FONT face=宋体>数据须放在单个表空间页面上,4k的不能超过1024*4-4</FONT></TD></TR>
<TR style="HEIGHT: 24pt; mso-height-source: userset" height=32>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 24pt; BACKGROUND-COLOR: transparent" height=32><FONT face=宋体>long varchar</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>大型变长字符串</FONT></TD>
<TD class=xl69 style="BORDER-RIGHT: black 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" colSpan=2><FONT face=宋体>不需指定最大长度，最大可存储32700个字节</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>不受表空间页大小限制</FONT></TD></TR>
<TR style="HEIGHT: 27pt" height=36>
<TD class=xl68 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: #d4d0c8; BORDER-LEFT: windowtext; BORDER-BOTTOM: #d4d0c8; HEIGHT: 27pt; BACKGROUND-COLOR: transparent" height=36><FONT face=宋体>CLOB</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>大对象字符串</FONT></TD>
<TD class=xl69 style="BORDER-RIGHT: black 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" colSpan=2><FONT face=宋体>须指定长度,例CLOB(n[K|M|G]),最大2G字节</FONT></TD>
<TD class=xl82 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; WIDTH: 115pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=153><FONT face=宋体>存放在表空间,表中存放的是一个指针</FONT></TD></TR>
<TR style="HEIGHT: 13.5pt" height=18>
<TD class=xl66 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext 0.5pt solid; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 54pt; BACKGROUND-COLOR: transparent" height=72 rowSpan=4><FONT face=宋体>双字节</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>graphic</FONT></TD>
<TD class=xl73 style="BORDER-RIGHT: black 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 309pt; BORDER-BOTTOM: black 0.5pt solid; BACKGROUND-COLOR: transparent" width=412 colSpan=3 rowSpan=4><FONT face=宋体>分别与前面的CHAR,VARCHAR,LONG VARCHAR和CLOB对应，只是都存储双字节字符，存储的长度都减少一半</FONT></TD>
<TD class=xl83 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext 0.5pt solid; BORDER-BOTTOM: black 0.5pt solid; BACKGROUND-COLOR: transparent" rowSpan=4><FONT face=宋体>　</FONT></TD></TR>
<TR style="HEIGHT: 13.5pt" height=18>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 13.5pt; BACKGROUND-COLOR: transparent" height=18><FONT face=宋体>vargraphic</FONT></TD></TR>
<TR style="HEIGHT: 13.5pt" height=18>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 13.5pt; BACKGROUND-COLOR: transparent" height=18><FONT face=宋体>longpraphic</FONT></TD></TR>
<TR style="HEIGHT: 13.5pt" height=18>
<TD class=xl68 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: #d4d0c8; BORDER-LEFT: windowtext; BORDER-BOTTOM: #d4d0c8; HEIGHT: 13.5pt; BACKGROUND-COLOR: transparent" height=18><FONT face=宋体>DBCLOB</FONT></TD></TR>
<TR style="HEIGHT: 27.75pt; mso-height-source: userset" height=37>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext 0.5pt solid; BORDER-BOTTOM: windowtext 0.5pt solid; HEIGHT: 27.75pt; BACKGROUND-COLOR: transparent" height=37><FONT face=宋体>二进制</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>BLOB</FONT></TD>
<TD class=xl65 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent"><FONT face=宋体>二进制大对象</FONT></TD>
<TD class=xl67 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; BORDER-LEFT: windowtext; WIDTH: 222pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=296 colSpan=2><FONT face=宋体>需制定长度，例BLOB(n[K|M|G]),表中存放的也是指针，指向实际的数据</FONT></TD>
<TD class=xl82 style="BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext; BORDER-LEFT: windowtext; WIDTH: 115pt; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" width=153><FONT face=宋体>存放图片、视频、音频等容量大的内容</FONT></TD></TR></TBODY></TABLE></DIV>
<DIV> </DIV>
<DIV><STRONG>日期时间型：</STRONG></DIV>
<DIV>包括DATE,TIME和TIMESTAMP三种</DIV>
<DIV>date  叫日期型，可表示公元1年到9999年中任何一天，显示的是固定长度的10位字符串，</DIV>
<DIV>          在硬盘上占用4个字节，压缩字符串形式储存</DIV>
<DIV>time  时间性 ，可表示一天中的时、分、秒，显示出来的是固定长度的8位字符串，在硬盘上占用3个字节位，压缩字符串保存</DIV>
<DIV>timestamp 时间戳型，可表示年月日、时分秒，可精确到微妙级别</DIV>
<DIV> </DIV>
<DIV><STRONG>XML类型：</STRONG></DIV>
<DIV>可用XQuery直接对XML这种层次型的数据进行操作。可直接把XML数据作为内容存放到表中</DIV>
<DIV>从V9.5开始，长度较短的XML数据直接放在表中，长度很长的XML数据单独存放在另外的表空间中</DIV>
<DIV> </DIV>
<DIV><STRONG>空值：</STRONG></DIV>
<DIV>用NULL表示，可放在任意的数据类型中表示不存在</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>

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