Sql语句操作类

虽然数据库语句在直接出现在程序中很少（都以存储过程代替），但是在搜索时会出现部分Sql语句的拼装问题。 

SqlHelper.cs

using System;
using System.Collections;
using System.Data;
using System.Data.Common;
using System.Text;
using System.Text.RegularExpressions;

namespace Beasyer.Lib
...{
    /**//// <summary>
    /// 包装ＳＱＬ的操作
    /// </summary>
    public static class SqlHelper
    ...{
       

        /**//// <summary>
        /// //追加查询条件
        /// </summary>
        /// <param name="sql">原本的SQL语句</param>
        /// <param name="where">要追加的where语句,不能带where</param>
        /// <returns></returns>
        public static string AppendWhereToSql(string sql, string where)
        ...{
            if (string.IsNullOrEmpty(sql))
            ...{
                return string.Empty;
            }
            else
            ...{
                if(string.IsNullOrEmpty(where))
                ...{
                    return sql;
                }
                else
                ...{
                    if(sql.ToLower().IndexOf("where")>0)
                    ...{
                        int whereint=sql.ToLower().IndexOf("where");
                        return sql.Substring(0,whereint+6)+where+sql.Substring(10,sql.Length-whereint-6);
                    }
                    else
                    ...{
                        return sql+" where "+where;
                    }
                }
            }
        }


        /**//// <summary>
        /// 组合两个ＳＱＬ中的条件语句反回带WHERE的语句
        /// </summary>
        /// <param name="where1"></param>
        /// <param name="where2"></param>
        /// <returns></returns>
        public static string UnionTwoWhereString(string where1, string where2)
        ...{
            where1.Trim();
            where2.Trim();
            if (where1 == null) where1 = "";
            if (where2 == null) where2 = "";
            string retStr;
            if (where1 != "" && where2 != "")
            ...{
                retStr = " WHERE" + " (" + where1 + ")and(" + where2 + ")";
            }
            else if (where1 == "" && where2 == "")
            ...{
                retStr = "";
            }
            else
            ...{
                retStr = " WHERE" + " " + where1 + where2;
            }
            return retStr;
        }

        /**//// <summary>
        /// 更换查询语句中的第一个查询字段列表
        /// </summary>
        /// <param name="insql">查询语句</param>
        /// <param name="newlist">替换列表</param>
        public static string ReplaceFirstList(string insql, string newList)
        ...{
            string sql = String.Copy(insql);
            CheckObjectHelper.ArgumentNotNullOrEmptyString(sql, "sql");
            CheckObjectHelper.ArgumentNotNullOrEmptyString(newList, "newList");
            int startPoint;
            int endPoint;
            string upSql = sql.ToUpper();
            startPoint = upSql.IndexOf("SELECT");
            if (startPoint == -1)
            ...{
                throw new ApplicationException("你提供了不正确的查询语句。（" + sql + "）");
            }
            else
            ...{
                startPoint = startPoint + 6;
            }
            endPoint = upSql.IndexOf("FROM");
            if (endPoint == -1)
            ...{
                throw new ApplicationException("你提供了不正确的查询语句。（" + sql + "）");
            }
            return sql.Replace(sql.Substring(startPoint, endPoint - startPoint), " " + newList + " ");
        }
    }
}