SQL Server 游标生成工具 技术原理和源代码分享
经常做ERP报表，涉及存储过程中读取数据，多个表之间关联的数据读取，用到游标。经典的读取用户表的游标例子
Declare @Age int Declare @Name varchar(20) Declare Cur Cursor For Select Age,Name From T_User Open Cur Fetch next From Cur Into @Age,@Name While @@fetch_status=0 Begin Update T_User Set [Name]=@Name,Age=@Age Fetch Next From Cur Into @Age,@Name End Close Cur Deallocate Cur
在实际应用时，经常需要找到这个模板，然后再根据实际的表结果，重写一遍。经常遇到以下二个问题
1 上面的例子脚本不知道放在哪里了，或是有很多例子脚本，不方便很快找出来
2 重写游标的例子，经常重复，又没有技术难度可言。比如读取工作单生产计划，读取用户。
经过思考，于是写个游标生成工具，把上面的模板代码，应用到代码生成器中。
注意上图中的Script Cursor，这是用来生成游标模板的。选择一个数据库，树左边选择表名，勾选字段值，点击执行
DECLARE @UserID NVARCHAR(10) DECLARE @UserName NVARCHAR(50) DECLARE Cur CURSOR FOR SELECT [UserID],[UserName] FROM [USER] OPEN Cur FETCH next FROM Cur INTO @UserID,@UserName WHILE @@fetch_status=0 BEGIN FETCH next FROM Cur INTO @UserID,@UserName END CLOSE Cur DEALLOCATE Cur
源代码不到50行，全文如下
List<ColumnInfo> fieldlist = this.GetFieldlist(); StringBuilder builder=new StringBuilder(); string typeName = string.Empty; foreach (ColumnInfo columnInfo in fieldlist) { switch (columnInfo.TypeName) { case "datetime": case "int": case "image": case "bit": typeName = columnInfo.TypeName; break; case "nvarchar": case "nchar": case "varchar": case "char": typeName =string.Format("{0}({1})", columnInfo.TypeName,columnInfo.Length); break; } builder.AppendLine(string.Format("Declare @{0} {1}", columnInfo.ColumnName, typeName)); } var columns = string.Join(",", (from column in fieldlist select "["+column.ColumnName+"]").ToArray()); string fetchNex= string.Join(",", (from column in fieldlist select "@"+column.ColumnName).ToArray()); string update= string.Join(",", (from column in fieldlist select "@"+column.ColumnName+"=["+ column.ColumnName+"]").ToArray()); builder.AppendLine(string.Format("Declare Cur Cursor For Select {0} From [{1}] ", columns, this.tablename)); builder.AppendLine("Open Cur"); builder.AppendLine(string.Format("Fetch next From Cur Into {0} ", fetchNex)); builder.AppendLine("While @@fetch_status=0 "); builder.AppendLine("Begin"); //builder.AppendLine(string.Format(" Update [{0}] Set {1} ",this.tablename,update)); builder.AppendLine(string.Format(" Fetch next From Cur Into {0} ", fetchNex)); builder.AppendLine("End "); builder.AppendLine("Close Cur "); builder.AppendLine("Deallocate Cur");
有以下几点需要注意
1 生成的脚本中，字段名称，表名称，均要加上方括号，以避免名称重突。
2 最后生成的SQL源代码，还需要应用下面的方法，将SQL关键字大写。
将SQL查询语句的关键字大写的方法来自CSDN下载区，全文如下
private static Regex RegexSQLCapitalize = new Regex("\\badd\\b|\\baggregate\\b|\\baction\\b|\\balter\\b|\\bas\\b|\\basc\\b|\\basymmetric\\b|\\bauthorization\\b|\\bbegin\\b|\\bbinary\\b|\\bbit\\b|\\bby\\b|\\bcascade\\b|\\bcase\\b|\\bcatalog\\b|\\bcharacter\\b|\\bchar\\b|\\bcheck\\b|\\bcheckpoint\\b|\\bclose\\b|\\bclustered\\b|\\bconstraint\\b|\\bcollate\\b|\\bcolumn\\b|\\bcommit\\b|\\bcontains\\b|\\bcontinue\\b|\\bcreate\\b|\\bcross\\b|\\bcursor\\b|\\bdatabase\\b|\\bdeallocate\\b|\\bdesc\\b|\\bdecimal\\b|\\bdeclare\\b|\\bdefault\\b|\\bdelete\\b|\\bdesc\\b|\\bdistinct\\b|\\bdouble\\b|\\bdrop\\b|\\belse\\b|\\bend\\b|\\bescape\\b|\\bexcept\\b|\\bexec\\b|\\bexecute\\b|\\bexternal\\b|\\bfetch\\b|\\bfloat\\b|\\bforeign\\b|\\bfor\\b|\\bfrom\\b|\\bfunction\\b|\\bget\\b|\\bgroup\\b|\\bgoto\\b|\\bgrant\\b|\\bhaving\\b|\\bidentity\\b|\\binto\\b|\\bindex\\b|\\binsert\\b|\\binstead\\b|\\bint\\b|\\bkey\\b|\\bname\\b|\\bof\\b|\\bon\\b|\\bopen\\b|\\boption\\b|\\border\\b|\\boutput\\b|\\bprimary\\b|\\breturn\\b|\\brollback\\b|\\bschema\\b|\\bselect\\b|\\bsize\\b|\\bsymmetric\\b|\\bset\\b|\\bserver\\b|(\\btable\\b)|\\bthen\\b|\\btop\\b|\\btime\\b|\\btimestamp\\b|\\bto\\b|\\btrigger\\b|\\bprocedure\\b|\\btype\\b|\\bunion\\b|\\bunique\\b|\\bupdate\\b|\\buse\\b|\\bvalues\\b|\\bvalue\\b|\\bvarchar\\b|\\bview\\b|\\bwhen\\b|\\bwhile\\b|\\bwhere\\b|\\bwith\\b|\\bnvarchar\\b|\\bnchar\\b|\\bdatetime\\b|\\bfloat\\b|\\bdate\\b|\\bdatediff\\b|\\bdateadd\\b|\\bdatename\\b|\\bdatepart\\b|getdate|\\breferences\\b|\\babs\\b|\\bavg\\b|\\bcast\\b|\\bconvert\\b|\\bcount\\b|\\bday\\b|\\bisnull\\b|\\blen\\b|\\bmax\\b|\\bmin\\b|\\bmonth\\b|\\byear\\b|\\breplace\\b|\\bsubstring\\b|\\bsum\\b|\\bupper\\b|\\buser\\b|\\ball\\b|\\bany\\b|\\band\\b|\\bbetween\\b|\\bexists\\b|\\bin\\b|\\binner\\b|\\bis\\b|\\bjoin\\b|\\bleft\\b|\\blike\\b|\\bnot\\b|\\bnull\\b|\\bor\\b|\\bright\\b|\\btry\\b|\\bcatch\\b", RegexOptions.IgnoreCase); public static string CapitalizeSQLClause(string source) { //先按行划分 Regex rowReg = new Regex("\r\n"); string[] strRows = rowReg.Split(source); StringBuilder strBuilder = new StringBuilder(); int rowsCount = strRows.Length; for (int i = 0; i < rowsCount; i++) { //去掉一行中的一个或多个空白 //strRows[i] = Regex.Replace(strRows[i], @"\s+", " "); //按空格划分 string[] strWords = strRows[i].Split(new char['\0']); int wordsCount = strWords.Length; for (int j = 0; j < wordsCount; j++) { strBuilder.Append(" "); if (RegexSQLCapitalize.IsMatch(strWords[j])) { MatchCollection mc = RegexSQLCapitalize.Matches(strWords[j]); int mcCount = mc.Count; for (int k = 0; k < mcCount; k++) { strWords[j] = strWords[j].Replace(mc[k].Value, mc[k].Value.ToUpper()); } strBuilder.Append(strWords[j]); } else { strBuilder.Append(strWords[j]); } strBuilder.Append(" "); } strBuilder.Append("\r\n"); } return strBuilder.ToString().Replace("\r\n\r\n", "\r\n"); }
正则表达式替换字符串中的关键字，这个方法没有任何依赖，可拷贝到您的项目或类库中，为SQL 脚本增加关键字大写功能。
3 SQL 脚本格式化功能 如果能把生成的SQL脚本格式化一下，生成美观的SQL脚本，增加可读性。SQL Pretty Printer可以做到，但是没有找到API可以调用这个功能。
4 多表关联的游标模板没有做到。应该尝试从多个关联表中生成游标。不过表与表之间的关系难以自动生成，比如像下面的母子表游标询语句
Declare Cur Cursor For Select r.Description,r.WorkCenter FROM JobOrder j, JobOrderRouting r WHERE j.JobNo=r.JobNo Open Cur
游标要从2个关联的表中读取数据，如果2个表之间有外键关联，可以生成2个表的外键关联字段的关系，也就是上面的SQL游标可以自动生成，但是有的2个表之间没有外键关联的，还是要手工指定，相当于是个半成品的游标生成器，于是只好把这个功能点拿掉，只做最简单的一种情况，生成一个表的若干个字段的游标查询，没有设计多表查询的游标。
