学习了。

关于第8条
根据【越有效地缩小范围的条件越放后】的原则，我觉得第一条sql效率高啊

xh_bz=1 就摔选到只有5%的数据了，

然后在这5%的数据里面选择dy_dj = '1KV以下'

不对么？


关于第9条，我在另一篇文章上看到，数据库（oracle）是从右到左解析的，所以应该把数据量小的放在后面，这种说法是不是跟你的有矛盾？

收藏

已阅

谢谢啊，

象这样的代码应该是全局代码并且是只初始化一次的时候才有用吧？这个例子好像没有考虑多次创建一个Car对象的实例需要花费的时间。

不错，谢谢

我也正在看ActiveRecord.

looks horrible in firefox

在MSDN中就有

好

<TABLE ID="oTable" BORDER BGCOLOR="lightslategray">
<TBODY ID="oTBody0"></TBODY>
<TBODY ID="oTBody1"></TBODY>
</TABLE>

<SCRIPT LANGUAGE="JScript">
// Declare variables and create the header, footer, and caption.
var oTHead = oTable.createTHead();
var oTFoot = oTable.createTFoot();
var oCaption = oTable.createCaption();
var oRow, oCell;
var i, j;

// Declare stock data that would normally be retrieved from a stock Web site.
var heading = new Array;

heading[0] = "Stock symbol";
heading[1] = "High";
heading[2] = "Low";
heading[3] = "Close";

var stock = new Array;

stock["0,0"] = "ABCD";
stock["0,1"] = "88.625";
stock["0,2"] = "85.50";
stock["0,3"] = "85.81";

stock["1,0"] = "EFGH";
stock["1,1"] = "102.75";
stock["1,2"] = "97.50";
stock["1,3"] = "100.063";

stock["2,0"] = "IJKL";
stock["2,1"] = "56.125";
stock["2,2"] = "54.50";
stock["2,3"] = "55.688";

stock["3,0"] = "MNOP";
stock["3,1"] = "71.75";
stock["3,2"] = "69.00";
stock["3,3"] = "69.00";

// Insert a row into the header.
oRow = oTHead.insertRow();
oTHead.bgColor = "lightskyblue";

// Insert cells into the header row.
for (i=0; i<4; i++)
{
oCell = oRow.insertCell();
oCell.align = "center";
oCell.style.fontWeight = "bold";
oCell.innerText = heading[i];
}

// Insert rows and cells into the first body.
for (i=0; i<2; i++)
{
oRow = oTBody0.insertRow();
for (j=0; j<4; j++)
{
oCell = oRow.insertCell();
oCell.innerText = stock[i + "," + j];
}
}

// Set the background color of the first body.
oTBody0.bgColor = "lemonchiffon";

// Insert rows and cells into the second body.
for (i=2; i<4; i++)
{
oRow = oTBody1.insertRow();
for (j=0; j<4; j++)
{
oCell = oRow.insertCell();
oCell.innerText = stock[i + "," + j];
}
}

// Set the background color of the second body.
oTBody1.bgColor = "goldenrod";

// Insert rows and cells into the footer row.
oRow = oTFoot.insertRow();
oCell = oRow.insertCell();
oCell.innerText = "Quotes are for example only.";
oCell.colSpan = "4";
oCell.bgColor = "lightskyblue";

// Set the innerText of the caption and position it at the bottom of the table.
oCaption.innerText = "Created using Table Object Model."
oCaption.style.fontSize = "10";
oCaption.align = "bottom";
</SCRIPT>

有趣

用例也太简单了吧？

通过使用XML实现的Schema与DataSet之间建立关系，从而使数据在异构的分布式系统中相互通信

增加理解上的难度，和维护的代价。一个新工具如果不能简化你原来的工作和减轻理解上的负担，不用也罢。

哦，解决了！有必要再继续深入了解一下交易

代码已修改，以前的错误在于不属于同一事务。

代码好像没对哦

不错