对于交叉表的实现及多重表头的应用

本例所采用的交叉表的实现方式是建立在SQL的基础上，所以可能会由于使用的数据库不一致需要修改SQL，本例采用的是oracle9i，多重表头实现控件为C1FlexGrid。 首先看一个交叉表的SQL： select name, sum(case when km='英语' and type = '1' then cj else 0 end) as 英语_1, sum(case when km='英语' and type = '2' then cj else 0 end) as 英语_1, sum(case when km='数学' and type = '1' then cj else 0 end) as 数学_1, sum(case when km='数学' and type = '2' then cj else 0 end) as 数学_2, sum(case when km='语文' and type = '1' then cj else 0 end) as 语文_1, sum(case when km='语文' and type = '2' then cj else 0 end) as 语文_2 from test group by name; 数据表结构如：name km type cj

姓名	语文		数学
	其中	期末	期中	期末
张	12	2	44	55
李	24	2	55	5

交叉表效果 本SQL是将一个学生成绩按课目，期中、期末进行统计，就能够实现以人名为汇总的按课目、期数的交叉表，在这个交叉表中会有一个缺陷 1）可能由于课目并非固定而此sql就需要动态构建 2）可能并非所有课目都会有期中、期末成绩，那么就需要只对有期中或期末成绩的课目按期数做汇总 为此，需要通过动态构造交叉表，可考虑使用存储过程或程序构造sql，本人用C#写了一个通用的构造sql函数，但目前只支持3层交叉表头 ///

/// 购造交叉表，最多支持3层（如果递归将无限层，但sql长度有限制），只支持一列汇总列,增加了对数据的过滤 /// 如果添加汇总列无数据则不加入结果列中 ///

/// 基础表名 /// group列，主列 /// 需要交叉的列 /// 基础表过滤条件 /// 汇总的数据列 /// private string GetCrossSQL(string stablename, string spricols, string scrosscols, string sfilter, string sumcol) { string strSQL = ""; //第一步先获取需要交叉的字段的列表 string[] s = scrosscols.Split(','); ArrayList al_cols = new ArrayList(); for (int i = 0; i < s.Length; i++) { string s_temp = ""; s_temp = "select distinct " + s[i] + " from " + stablename + sfilter; DataTable dt_temp = this.dac.ExecuteDataTable(s_temp); al_cols.Add(dt_temp); } //第二步，构造sum语句 string sumsql = ""; switch (s.Length) { case 1: foreach (DataRow row0 in (al_cols[0] as DataTable).Rows) { string s_temp = " sum( case when " + s[0] + "='" + row0[0].ToString() + "' then " + sumcol + " else 0 end ) as " + s[0].Substring(0,2)+"_"+row0[0].ToString().Trim(); if (IsExistCol(stablename, spricols, sfilter, s_temp)) { sumsql += "," + s_temp; } } break; case 2: foreach (DataRow row0 in (al_cols[0] as DataTable).Rows) { foreach (DataRow row1 in (al_cols[1] as DataTable).Rows) { string s_temp = "sum( case when " + s[0] + "='" + row0[0].ToString() + "' and " + s[1] + "= '" + row1[0].ToString() + "' then " + sumcol + " else 0 end ) as " + s[0].Substring(0,2)+"_"+row0[0].ToString().Trim() + "#" +s[1].Substring(0,2)+"_"+ row1[0].ToString().Trim(); if (IsExistCol(stablename, spricols, sfilter, s_temp)) { sumsql += "," + s_temp; } } } break; case 3: foreach (DataRow row0 in (al_cols[0] as DataTable).Rows) { foreach (DataRow row1 in (al_cols[1] as DataTable).Rows) { foreach (DataRow row2 in (al_cols[2] as DataTable).Rows) { //sumsql += ",sum( case when " + s[0] + "='" + row0[0].ToString() + "' and " + s[1] + "= '" + row1[0].ToString() + "' and " + s[2] + "='" + row2.ToString() + "' then " + sumcol + " else 0 end ) as " + s[0].Trim() + "#" + row0[0].ToString().Trim() + "_" + s[1].Trim() + "#" + row1[0].ToString().Trim() + "_" + s[2].Trim() + "#" + row2[0].ToString().Trim(); string s_temp = "sum( case when " + s[0] + "='" + row0[0].ToString() + "' and " + s[1] + "= '" + row1[0].ToString() + "' and " + s[2] + "='" + row2[0].ToString() + "' then " + sumcol + " else 0 end ) as "+ s[0].Substring(0,2)+"_"+row0[0].ToString().Trim() + "#" +s[1].Substring(0,2)+"_"+ row1[0].ToString().Trim() + "#" +s[2].Substring(0,2)+"_"+ row2[0].ToString().Trim(); if (IsExistCol(stablename, spricols, sfilter, s_temp)) { sumsql += "," + s_temp; } } } } break; } //拼接sql strSQL = " select " + spricols + sumsql + " from " + stablename + " " + sfilter + " group by " + spricols; return strSQL; } private bool IsExistCol(string stablename, string spricols, string sfilter, string sumsql) { string strSQL = " select " + sumsql + " from " + stablename + " " + sfilter ; try { if (Convert.ToDecimal(this.dac.ExecuteScalar(CommandType.Text, strSQL).ToString()) != 0) return true; else return false; } catch (System.Exception se) { return false; } } 如上执行sql将会得到一个构造好的sql，由于本人还需要用它做多重表头，所以在考虑了字段名做了些标记，以‘#’，‘-’做表头名值转化，以下是使用C1FlexGrid实现对多重表头的构造 public void CreateGridTitle(C1.Win.C1FlexGrid.C1FlexGrid grid, DataTable dt_data) { grid.AllowAddNew = true; //第一步获取所有的数据表头，并获取最大表头行数 grid.AllowMerging = C1.Win.C1FlexGrid.AllowMergingEnum.FixedOnly; ArrayList al_title = new ArrayList(); int fixrow = 0; for (int i = 0; i < dt_data.Columns.Count; i++) { string[] s = dt_data.Columns[i].Caption.Split('#'); al_title.Add(s); if (s.Length > fixrow) fixrow = s.Length; } //插入表头 grid.Rows.Fixed = fixrow; for (int i = 0; i < grid.Cols.Count; i++) { grid.Cols[i].AllowMerging = true; } for (int i = 1; i <= dt_data.Columns.Count; i++) { for (int j = 0; j < fixrow; j++) { if (grid.Rows.Count < fixrow) grid.Rows.Add(); if ((al_title[i - 1] as string[]).Length <= j) grid[j, i] = (al_title[i - 1] as string[])[(al_title[i - 1] as string[]).Length - 1].Trim(); else grid[j, i] = (al_title[i - 1] as string[])[j].Trim(); grid.Rows[j].AllowMerging = true; } } grid.Styles.Fixed.TextAlign = C1.Win.C1FlexGrid.TextAlignEnum.CenterCenter; } 基本过程就如以上示例，根据实际情况可以对以上方法再做改进，比如可以设计一个动态配置交叉表工具。 由于太忙，没有功夫去自己研究，该方法也就提供入门指引，待日后再做细化了。

转载于:https://www.cnblogs.com/oldkingsir/archive/2008/07/10/2365647.html