SQL Server 游標生成工具 技術原理和源代碼分享

經常做ERP報表，涉及存儲過程中讀取數據，多個表之間關聯的數據讀取，用到游標。經典的讀取用戶表的游標例子

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

在實際應用時，經常需要找到這個模板，然后再根據實際的表結果，重寫一遍。經常遇到以下二個問題

1  上面的例子腳本不知道放在哪里了，或是有很多例子腳本，不方便很快找出來

2  重寫游標的例子，經常重復，又沒有技術難度可言。比如讀取工作單生產計划，讀取用戶。

經過思考，於是寫個游標生成工具，把上面的模板代碼，應用到代碼生成器中。

注意上圖中的Script Cursor，這是用來生成游標模板的。選擇一個數據庫，樹左邊選擇表名，勾選字段值，點擊執行

 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 

 

源代碼不到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");

有以下幾點需要注意

1  生成的腳本中，字段名稱，表名稱，均要加上方括號，以避免名稱重突。

2  最后生成的SQL源代碼，還需要應用下面的方法，將SQL關鍵字大寫。

將SQL查詢語句的關鍵字大寫的方法來自CSDN下載區，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++)
            {
                //去掉一行中的一個或多個空白
                //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");
 }

正則表達式替換字符串中的關鍵字，這個方法沒有任何依賴，可拷貝到您的項目或類庫中，為SQL 腳本增加關鍵字大寫功能。

 

3  SQL 腳本格式化功能  如果能把生成的SQL腳本格式化一下，生成美觀的SQL腳本，增加可讀性。SQL Pretty Printer可以做到，但是沒有找到API可以調用這個功能。

4 多表關聯的游標模板沒有做到。應該嘗試從多個關聯表中生成游標。不過表與表之間的關系難以自動生成，比如像下面的母子表游標詢語句

Declare Cur Cursor For Select r.Description,r.WorkCenter  FROM JobOrder  j, JobOrderRouting r
     WHERE j.JobNo=r.JobNo
Open Cur

游標要從2個關聯的表中讀取數據，如果2個表之間有外鍵關聯，可以生成2個表的外鍵關聯字段的關系，也就是上面的SQL游標可以自動生成，但是有的2個表之間沒有外鍵關聯的，還是要手工指定，相當於是個半成品的游標生成器，於是只好把這個功能點拿掉，只做最簡單的一種情況，生成一個表的若干個字段的游標查詢，沒有設計多表查詢的游標。