C#拼接SQL语句，SQL Server 2005+，多行多列大数据量情况下，使用ROW_NUMBER实现的高效分页排序

/// <summary>
/// 单表（视图）获取分页SQL语句
/// </summary>
/// <param name="tableName">表名或视图名</param>
/// <param name="key">唯一键</param>
/// <param name="fields">获取的字段</param>
/// <param name="condition">查询条件（不包含WHERE）</param>
/// <param name="collatingSequence">排序规则（不包含ORDER BY）</param>
/// <param name="pageSize">页大小</param>
/// <param name="pageIndex">页码（从1开始）</param>
/// <returns>分页SQL语句</returns>
public static string GetPagingSQL(
string tableName,
string key,
string fields,
string condition,
string collatingSequence,
int pageSize,
int pageIndex)
{
string whereClause = string.Empty;
if (!string.IsNullOrEmpty(condition))
{
whereClause = string.Format("WHERE {0}", condition);
}

if (string.IsNullOrEmpty(collatingSequence))
{
collatingSequence = string.Format("{0} ASC", key);
}

StringBuilder sbSql = new StringBuilder();

sbSql.AppendFormat("SELECT {0} ", PrependTableName(tableName, fields, ','));
sbSql.AppendFormat("FROM ( SELECT TOP {0} ", pageSize * pageIndex);
sbSql.AppendFormat(" [_RowNum_] = ROW_NUMBER() OVER ( ORDER BY {0} ), ", collatingSequence);
sbSql.AppendFormat(" {0} ", key);
sbSql.AppendFormat(" FROM {0} ", tableName);
sbSql.AppendFormat(" {0} ", whereClause);
sbSql.AppendFormat(" ) AS [_TempTable_] ");
sbSql.AppendFormat(" INNER JOIN {0} ON [_TempTable_].{1} = {0}.{1} ", tableName, key);
sbSql.AppendFormat("WHERE [_TempTable_].[_RowNum_] > {0} ", pageSize * (pageIndex - 1));
sbSql.AppendFormat("ORDER BY [_TempTable_].[_RowNum_] ASC ");

return sbSql.ToString();
}

/// <summary>
/// 给字段添加表名前缀
/// </summary>
/// <param name="tableName">表名</param>
/// <param name="fields">字段</param>
/// <param name="separator">标识字段间的分隔符</param>
/// <returns></returns>
public static string PrependTableName(string tableName, string fields, char separator)
{
StringBuilder sbFields = new StringBuilder();

string[] fieldArr = fields.Trim(separator).Split(separator);
foreach (string str in fieldArr)
{
sbFields.AppendFormat("{0}.{1}{2}", tableName, str.Trim(), separator);
}

return sbFields.ToString().TrimEnd(separator);
}

假设有如下产品表：

CREATE TABLE [dbo].[Tbl_Product]
(
[ID] [int] IDENTITY(1, 1)
NOT NULL ,
[ProductId] [varchar](50) NOT NULL ,
[ProductName] [nvarchar](50) NOT NULL ,
[IsDeleted] [int] NOT NULL
CONSTRAINT [DF_Tbl_Product_IsDeleted] DEFAULT ( (0) ) ,
CONSTRAINT [PK_Tbl_Product] PRIMARY KEY CLUSTERED ( [ProductId] ASC )
WITH ( PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF,
IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON,
ALLOW_PAGE_LOCKS = ON ) ON [PRIMARY]
)
ON [PRIMARY]

1. Tbl_Product->ID（序号，非空，自增）
2. Tbl_Product->ProductId（产品Id，主键）
3. Tbl_Product->ProductName（产品名称，非空）
4. Tbl_Product->IsDeleted（虚拟删除标记，非空）

调用BasicFunction.GetPagingSQL("Tbl_Product", "ID", "ID,ProductId,ProductName", "IsDeleted=0", "ProductName ASC, ID DESC", 5, 5)，BasicFunction为分页排序方法所在的静态类，生成的分页排序SQL语句如下（已手动调整了格式）：

SELECT Tbl_Product.ID ,
Tbl_Product.ProductId ,
Tbl_Product.ProductName
FROM ( SELECT TOP 25
[_RowNum_] = ROW_NUMBER() OVER ( ORDER BY ProductName ASC, ID DESC ) ,
ID
FROM Tbl_Product
WHERE IsDeleted = 0
) AS [_TempTable_]
INNER JOIN Tbl_Product ON [_TempTable_].ID = Tbl_Product.ID
WHERE [_TempTable_].[_RowNum_] > 20
ORDER BY [_TempTable_].[_RowNum_] ASC

• 查询的字段列表，去掉了不关心的字段（这里为IsDeleted，因为条件里面IsDeleted=0，查出来的产品都是没被删除的）；
• 排序依据，在调用该方法时，应尽量确保排序的依据可以唯一确定记录在结果集中的位置（这里添加了辅助排序依据，ID DESC，如果产品重名，添加的晚的排在前面）；
• 性能优化的一点儿建议：如果字段的值是统计出来的，通常是在视图中，且结果集很大，且需要对结果集分页排序，可以使用临时表规避不稳定的查询效率（关于不稳定的查询效率，会在之后的文章中示例）；
• 另外一点儿建议，使用ROW_NUMBER时，切记一定要和“TOP n”一起使用，n等于int.MaxValue都比不加“TOP n”时要快。

摘自：http://www.cnblogs.com/return8023/archive/2012/05/20/2510983.html