Excel在字串資料驗證方面的局限性

Curtis Chau

更新:8月 19, 2025

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Microsoft Excel 對字串清單的長度有一個已知的限制，即清單的總長度（包括逗號等分隔符號）不能超過 255 個字元。

當您在來源欄位中手動輸入字串列表，而不是從 Excel 表格中的現有範圍中選擇資料時，就會出現此問題，如下所示。

Excel 限制問題

解決 Excel 限制問題

針對此限制的標準解決方法是在工作表的列或行中建立值列表，而不是在來源欄位中輸入字串列表。如下圖所示。

Excel 限制解決方案範例

之後，在資料驗證中使用公式引用，例如 C1:C100，並指向該範圍。

這種方法可以繞過限制，讓你建立下拉清單而不受 255 個字元的限制。

IronXL 出現問題

IronXL 使用AddStringListRule方法將字串清單套用至資料驗證。但是，由於上述 Excel 中的字元限制，保存方法仍然有效。但是，需要注意的是，如果清單超過 255 個字符，則可能會導致嚴重問題：開啟檔案時 Excel 崩潰。下面舉個例子來說明這個問題。

using IronXL;
using IronXL.DataValidations;

// Set your license key here if you have one
IronXL.License.LicenseKey = "YOUR-LICENSE-KEY";
var workBook = WorkBook.Create(ExcelFileFormat.XLSX);

var sheet = workBook.CreateWorkSheet("Validation Rule Example using");
// Apply rules from row 2 down to row 500
var validationRangeStart = "2";
var validationRangeFinish = "500";

// --- 1. Define All Column Headers ---
sheet["A1"].Value = "String List Test";
sheet["B1"].Value = "Formula List Test";
sheet["A1:B1"].Style.Font.Bold = true;

// 256
string[] arrayString = new string[]
{
    "SKU-A01-R", "SKU-A02-R", "SKU-A03-R", "SKU-A04-R", "SKU-A05-R",
    "SKU-B01-G", "SKU-B02-G", "SKU-B03-G", "SKU-B04-G", "SKU-B05-G",
    "SKU-C01-B", "SKU-C02-B", "SKU-C03-B", "SKU-C04-B", "SKU-C05-B",
    "SKU-D01-Y", "SKU-D02-Y", "SKU-D03-Y", "SKU-D04-Y", "SKU-D05-Y",
    "END-001", "END-002", "END-003", "END-004", "END-005", "END-010", "END-001"
}; // total char with seperator 257 (230 char + 26 sperator [,] )

// no problem when write to a file
var skuValidation = sheet.DataValidations.AddStringListRule(sheet[$"A{validationRangeStart}:A{validationRangeFinish}"].RangeAddress, arrayString);

// set error box
skuValidation.ShowErrorBox = true;
skuValidation.ErrorBoxTitle = "Invalid SKU";
skuValidation.ErrorBoxText = "Please select a SKU from the list.";
skuValidation.ErrorAlert = ErrorAlert.Stop;

//attempt to save the file
var fileName = "CategoryProductCatalog.xlsx";
workBook.SaveAs(fileName);

using IronXL;
using IronXL.DataValidations;

// Set your license key here if you have one
IronXL.License.LicenseKey = "YOUR-LICENSE-KEY";
var workBook = WorkBook.Create(ExcelFileFormat.XLSX);

var sheet = workBook.CreateWorkSheet("Validation Rule Example using");
// Apply rules from row 2 down to row 500
var validationRangeStart = "2";
var validationRangeFinish = "500";

// --- 1. Define All Column Headers ---
sheet["A1"].Value = "String List Test";
sheet["B1"].Value = "Formula List Test";
sheet["A1:B1"].Style.Font.Bold = true;

// 256
string[] arrayString = new string[]
{
    "SKU-A01-R", "SKU-A02-R", "SKU-A03-R", "SKU-A04-R", "SKU-A05-R",
    "SKU-B01-G", "SKU-B02-G", "SKU-B03-G", "SKU-B04-G", "SKU-B05-G",
    "SKU-C01-B", "SKU-C02-B", "SKU-C03-B", "SKU-C04-B", "SKU-C05-B",
    "SKU-D01-Y", "SKU-D02-Y", "SKU-D03-Y", "SKU-D04-Y", "SKU-D05-Y",
    "END-001", "END-002", "END-003", "END-004", "END-005", "END-010", "END-001"
}; // total char with seperator 257 (230 char + 26 sperator [,] )

// no problem when write to a file
var skuValidation = sheet.DataValidations.AddStringListRule(sheet[$"A{validationRangeStart}:A{validationRangeFinish}"].RangeAddress, arrayString);

// set error box
skuValidation.ShowErrorBox = true;
skuValidation.ErrorBoxTitle = "Invalid SKU";
skuValidation.ErrorBoxText = "Please select a SKU from the list.";
skuValidation.ErrorAlert = ErrorAlert.Stop;

//attempt to save the file
var fileName = "CategoryProductCatalog.xlsx";
workBook.SaveAs(fileName);

Imports IronXL
Imports IronXL.DataValidations

' Set your license key here if you have one
IronXL.License.LicenseKey = "YOUR-LICENSE-KEY"
Dim workBook = WorkBook.Create(ExcelFileFormat.XLSX)

Dim sheet = workBook.CreateWorkSheet("Validation Rule Example using")
' Apply rules from row 2 down to row 500
Dim validationRangeStart = "2"
Dim validationRangeFinish = "500"

' --- 1. Define All Column Headers ---
sheet("A1").Value = "String List Test"
sheet("B1").Value = "Formula List Test"
sheet("A1:B1").Style.Font.Bold = True

' 256
Dim arrayString() As String = { "SKU-A01-R", "SKU-A02-R", "SKU-A03-R", "SKU-A04-R", "SKU-A05-R", "SKU-B01-G", "SKU-B02-G", "SKU-B03-G", "SKU-B04-G", "SKU-B05-G", "SKU-C01-B", "SKU-C02-B", "SKU-C03-B", "SKU-C04-B", "SKU-C05-B", "SKU-D01-Y", "SKU-D02-Y", "SKU-D03-Y", "SKU-D04-Y", "SKU-D05-Y", "END-001", "END-002", "END-003", "END-004", "END-005", "END-010", "END-001" }

' no problem when write to a file
Dim skuValidation = sheet.DataValidations.AddStringListRule(sheet($"A{validationRangeStart}:A{validationRangeFinish}").RangeAddress, arrayString)

' set error box
skuValidation.ShowErrorBox = True
skuValidation.ErrorBoxTitle = "Invalid SKU"
skuValidation.ErrorBoxText = "Please select a SKU from the list."
skuValidation.ErrorAlert = ErrorAlert.Stop

'attempt to save the file
Dim fileName = "CategoryProductCatalog.xlsx"
workBook.SaveAs(fileName)

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在程式碼中，我們嘗試將名為arrayString字串清單作為字串清單的來源，以建立下拉式清單。然後，我們嘗試將其儲存為CategoryProductCatalog.xlsx 。但是，由於這些限制，當使用 Microsoft Excel 開啟該檔案時，會顯示一則訊息，指出該檔案已損壞，無法開啟。

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IronXL 的解決方案

為了妥善解決 Excel 的這項限制，IronXL 提供了AddFormulaListRule方法，可透過DataValidations屬性取得。這種方法與使用 Excel 的解決方案類似。

我們首先將數值清單寫入工作表上的一系列儲存格。然後使用AddFormulaListRule將該範圍引用為下拉清單的資料來源。這有效地繞過了限制，方法與我們對 Excel 解決方案所使用的方法相同，但這次是透過程式設計實現的。

正確使用AddFormulaListRule可以繞過 Excel 的限制，同時也確保檔案在 Excel 中開啟時仍然可讀且穩定，即使包含很長的值清單。

程式碼範例

以下是規避此問題的其他範例程式碼。在同一個工作簿中，我們首先建立一個工作表，然後定義所有列標題。我們輸入上一個範例中的字串列表，以及新的資料來示範該功能。然後，我們使用上面給出的驗證範圍來呼叫AddFormulaListRule 。最後，我們將其儲存為validationRuleExample.xlsx 。為了確保工作簿沒有損壞且可以正常使用，我們在 Excel 中開啟它。這一步驟至關重要，因為它證明了我們的程式碼已成功實現。

using IronXL;
using IronXL.DataValidations;
using System;

// Set your license key here if you have one
IronXL.License.LicenseKey = "YOUR-LICENSE-KEY";
var workBook = WorkBook.Create(ExcelFileFormat.XLSX);

var sheet = workBook.CreateWorkSheet("Validation Rule Example using");
// Apply rules from row 2 down to row 500
var validationRangeStart = "2";
var validationRangeFinish = "500";

// --- 1. Define All Column Headers ---
sheet["A1"].Value = "String List Test";
sheet["B1"].Value = "Formula List Test";
sheet["A1:B1"].Style.Font.Bold = true;

string[] arrayString2 = new string[] 
{ 
    "SKU-A01-R", "SKU-A02-R", "SKU-A03-R", "SKU-A04-R", "SKU-A05-R",
    "SKU-B01-G", "SKU-B02-G", "SKU-B03-G", "SKU-B04-G", "SKU-B05-G",
    "SKU-C01-B", "SKU-C02-B", "SKU-C03-B", "SKU-C04-B", "SKU-C05-B",
    "SKU-D01-Y", "SKU-D02-Y", "SKU-D03-Y", "SKU-D04-Y", "SKU-D05-Y",
    "END-001", "END-002", "END-003", "END-004", "END-005", "END-010", "END-001",
    "IRON01","IRON02","IRON03","IRON04","IRON05","IRON06","IRON07","IRON08","IRON09","IRON10",
    "IRON11","IRON12","IRON13","IRON14","IRON15","IRON16","IRON17","IRON18","IRON19","IRON20",
    "IRON21","IRON22","IRON23","IRON24","IRON25","IRON26","IRON27","IRON28","IRON29","IRON30",
    "IRON31","IRON32","IRON33","IRON34","IRON35","IRON36","IRON37","IRON38","IRON39","IRON40",
    "IRON41","IRON42","IRON43","IRON44","IRON45","IRON46","IRON47","IRON48","IRON49","IRON50",
    "IRON51","IRON52","IRON53","IRON54","IRON55","IRON56","IRON57","IRON58","IRON59","IRON60",
    "IRON61","IRON62","IRON63","IRON64","IRON65","IRON66","IRON67","IRON68","IRON69","IRON70",
    "IRON71","IRON72","IRON73","IRON74","IRON75","IRON76","IRON77","IRON78","IRON79","IRON80",
    "IRON81","IRON82","IRON83","IRON84","IRON85","IRON86","IRON87","IRON88","IRON89","IRON90",
    "IRON91","IRON92","IRON93","IRON94","IRON95","IRON96","IRON97","IRON98","IRON99","IRON100"
}; // total char with seperator 257 (230 char + 26 sperator [,] )

//Write the contents of your array to column A of the data sheet.
for (int i = 0; i < arrayString2.Length; i++)
{
    // Note: IronXL row and cell indices are 1-based.
    sheet[$"A{i + 1}"].Value = arrayString2[i];
}

// Create the formula string that points to our data range.
// This will look like: 'ValidationData'!$A$1:$A$100

string formula = $"'{sheet.Name}'!$A$1:$A${arrayString2.Length}";
Console.WriteLine($"Generated formula for validation: {formula}");

var sku2Validation = sheet.DataValidations.AddFormulaListRule(sheet[$"B{validationRangeStart}:B{validationRangeFinish}"], formula);

sku2Validation.ShowErrorBox = true;
sku2Validation.ErrorBoxTitle = "Invalid SKU2";
sku2Validation.ErrorBoxText = "Please select a SKU from the list.";
sku2Validation.ErrorAlert = ErrorAlert.Stop;

// --- Final Touches ---
sheet.AutoSizeColumn(0, true);
sheet.AutoSizeColumn(1, true);

var fileName = "validationRuleExample.xlsx";
workBook.SaveAs(fileName);

Console.WriteLine($"Successfully created '{fileName}' with 2 validation rules example.");

using IronXL;
using IronXL.DataValidations;
using System;

// Set your license key here if you have one
IronXL.License.LicenseKey = "YOUR-LICENSE-KEY";
var workBook = WorkBook.Create(ExcelFileFormat.XLSX);

var sheet = workBook.CreateWorkSheet("Validation Rule Example using");
// Apply rules from row 2 down to row 500
var validationRangeStart = "2";
var validationRangeFinish = "500";

// --- 1. Define All Column Headers ---
sheet["A1"].Value = "String List Test";
sheet["B1"].Value = "Formula List Test";
sheet["A1:B1"].Style.Font.Bold = true;

string[] arrayString2 = new string[] 
{ 
    "SKU-A01-R", "SKU-A02-R", "SKU-A03-R", "SKU-A04-R", "SKU-A05-R",
    "SKU-B01-G", "SKU-B02-G", "SKU-B03-G", "SKU-B04-G", "SKU-B05-G",
    "SKU-C01-B", "SKU-C02-B", "SKU-C03-B", "SKU-C04-B", "SKU-C05-B",
    "SKU-D01-Y", "SKU-D02-Y", "SKU-D03-Y", "SKU-D04-Y", "SKU-D05-Y",
    "END-001", "END-002", "END-003", "END-004", "END-005", "END-010", "END-001",
    "IRON01","IRON02","IRON03","IRON04","IRON05","IRON06","IRON07","IRON08","IRON09","IRON10",
    "IRON11","IRON12","IRON13","IRON14","IRON15","IRON16","IRON17","IRON18","IRON19","IRON20",
    "IRON21","IRON22","IRON23","IRON24","IRON25","IRON26","IRON27","IRON28","IRON29","IRON30",
    "IRON31","IRON32","IRON33","IRON34","IRON35","IRON36","IRON37","IRON38","IRON39","IRON40",
    "IRON41","IRON42","IRON43","IRON44","IRON45","IRON46","IRON47","IRON48","IRON49","IRON50",
    "IRON51","IRON52","IRON53","IRON54","IRON55","IRON56","IRON57","IRON58","IRON59","IRON60",
    "IRON61","IRON62","IRON63","IRON64","IRON65","IRON66","IRON67","IRON68","IRON69","IRON70",
    "IRON71","IRON72","IRON73","IRON74","IRON75","IRON76","IRON77","IRON78","IRON79","IRON80",
    "IRON81","IRON82","IRON83","IRON84","IRON85","IRON86","IRON87","IRON88","IRON89","IRON90",
    "IRON91","IRON92","IRON93","IRON94","IRON95","IRON96","IRON97","IRON98","IRON99","IRON100"
}; // total char with seperator 257 (230 char + 26 sperator [,] )

//Write the contents of your array to column A of the data sheet.
for (int i = 0; i < arrayString2.Length; i++)
{
    // Note: IronXL row and cell indices are 1-based.
    sheet[$"A{i + 1}"].Value = arrayString2[i];
}

// Create the formula string that points to our data range.
// This will look like: 'ValidationData'!$A$1:$A$100

string formula = $"'{sheet.Name}'!$A$1:$A${arrayString2.Length}";
Console.WriteLine($"Generated formula for validation: {formula}");

var sku2Validation = sheet.DataValidations.AddFormulaListRule(sheet[$"B{validationRangeStart}:B{validationRangeFinish}"], formula);

sku2Validation.ShowErrorBox = true;
sku2Validation.ErrorBoxTitle = "Invalid SKU2";
sku2Validation.ErrorBoxText = "Please select a SKU from the list.";
sku2Validation.ErrorAlert = ErrorAlert.Stop;

// --- Final Touches ---
sheet.AutoSizeColumn(0, true);
sheet.AutoSizeColumn(1, true);

var fileName = "validationRuleExample.xlsx";
workBook.SaveAs(fileName);

Console.WriteLine($"Successfully created '{fileName}' with 2 validation rules example.");

Imports IronXL
Imports IronXL.DataValidations
Imports System

' Set your license key here if you have one
IronXL.License.LicenseKey = "YOUR-LICENSE-KEY"
Dim workBook = WorkBook.Create(ExcelFileFormat.XLSX)

Dim sheet = workBook.CreateWorkSheet("Validation Rule Example using")
' Apply rules from row 2 down to row 500
Dim validationRangeStart = "2"
Dim validationRangeFinish = "500"

' --- 1. Define All Column Headers ---
sheet("A1").Value = "String List Test"
sheet("B1").Value = "Formula List Test"
sheet("A1:B1").Style.Font.Bold = True

Dim arrayString2() As String = {"SKU-A01-R", "SKU-A02-R", "SKU-A03-R", "SKU-A04-R", "SKU-A05-R", "SKU-B01-G", "SKU-B02-G", "SKU-B03-G", "SKU-B04-G", "SKU-B05-G", "SKU-C01-B", "SKU-C02-B", "SKU-C03-B", "SKU-C04-B", "SKU-C05-B", "SKU-D01-Y", "SKU-D02-Y", "SKU-D03-Y", "SKU-D04-Y", "SKU-D05-Y", "END-001", "END-002", "END-003", "END-004", "END-005", "END-010", "END-001", "IRON01", "IRON02", "IRON03", "IRON04", "IRON05", "IRON06", "IRON07", "IRON08", "IRON09", "IRON10", "IRON11", "IRON12", "IRON13", "IRON14", "IRON15", "IRON16", "IRON17", "IRON18", "IRON19", "IRON20", "IRON21", "IRON22", "IRON23", "IRON24", "IRON25", "IRON26", "IRON27", "IRON28", "IRON29", "IRON30", "IRON31", "IRON32", "IRON33", "IRON34", "IRON35", "IRON36", "IRON37", "IRON38", "IRON39", "IRON40", "IRON41", "IRON42", "IRON43", "IRON44", "IRON45", "IRON46", "IRON47", "IRON48", "IRON49", "IRON50", "IRON51", "IRON52", "IRON53", "IRON54", "IRON55", "IRON56", "IRON57", "IRON58", "IRON59", "IRON60", "IRON61", "IRON62", "IRON63", "IRON64", "IRON65", "IRON66", "IRON67", "IRON68", "IRON69", "IRON70", "IRON71", "IRON72", "IRON73", "IRON74", "IRON75", "IRON76", "IRON77", "IRON78", "IRON79", "IRON80", "IRON81", "IRON82", "IRON83", "IRON84", "IRON85", "IRON86", "IRON87", "IRON88", "IRON89", "IRON90", "IRON91", "IRON92", "IRON93", "IRON94", "IRON95", "IRON96", "IRON97", "IRON98", "IRON99", "IRON100"}

'Write the contents of your array to column A of the data sheet.
For i As Integer = 0 To arrayString2.Length - 1
	' Note: IronXL row and cell indices are 1-based.
	sheet($"A{i + 1}").Value = arrayString2(i)
Next i

' Create the formula string that points to our data range.
' This will look like: 'ValidationData'!$A$1:$A$100

Dim formula As String = $"'{sheet.Name}'!$A$1:$A${arrayString2.Length}"
Console.WriteLine($"Generated formula for validation: {formula}")

Dim sku2Validation = sheet.DataValidations.AddFormulaListRule(sheet($"B{validationRangeStart}:B{validationRangeFinish}"), formula)

sku2Validation.ShowErrorBox = True
sku2Validation.ErrorBoxTitle = "Invalid SKU2"
sku2Validation.ErrorBoxText = "Please select a SKU from the list."
sku2Validation.ErrorAlert = ErrorAlert.Stop

' --- Final Touches ---
sheet.AutoSizeColumn(0, True)
sheet.AutoSizeColumn(1, True)

Dim fileName = "validationRuleExample.xlsx"
workBook.SaveAs(fileName)

Console.WriteLine($"Successfully created '{fileName}' with 2 validation rules example.")

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