sql-server – 执行SQL查询时在结果表中显示NULL值

2023年6月21日 345次阅读

我有一个执行SQL文件的脚本,并在控制台中打印结果(现在).问题是我需要区分NULL值和Result表中返回的空字符串.

这是查询在Management Studio中返回的内容：

《sql-server – 执行SQL查询时在结果表中显示NULL值》

您可以看到它包含字符串,空字符串和NULL值.

这是查询在PowerShell IDE中返回的内容：

《sql-server – 执行SQL查询时在结果表中显示NULL值》

NULL和empty之间没有区别.

最后几列也被剪切,只打印了前10列.

我该如何解决这个问题？

这是我的代码：

$ConnectionString = "Data Source=...;Initial Catalog=...;User Id=..;Password=.."
$FolderToSQLFiles = "C:\SQLFilesTestFolder";

#function that executes sql queries and return result tables
function GetSQLresults {
    Param(
        [Parameter(Mandatory=$True, ValueFromPipelineByPropertyName=$True, Position=0)] $SQLqueryText, # sql query text returned from file
    )

    $objConnection = New-Object System.Data.SqlClient.SqlConnection;
    $objConnection.ConnectionString = $ConnectionString

    $objConnection.Open();

    $ObjCmd = New-Object System.Data.SqlClient.SqlCommand;
    $ObjCmd.CommandText = $SQLqueryText;
    $ObjCmd.Connection = $objConnection;
    $ObjCmd.CommandTimeout = 0;

    $objAdapter = New-Object System.Data.SqlClient.SqlDataAdapter;
    $objAdapter.SelectCommand = $ObjCmd;
    $objDataSet = New-Object System.Data.DataSet;

    $objAdapter.Fill($objDataSet);

    $ResultSets = @(); #adding all result tables to array

    for ($i=0; $i -lt $objDataSet.Tables.Count; $i++) {
        $tmpResultTable = $objDataSet.Tables[$i] | Format-Table | Out-String;
        $ResultSets += $tmpResultTable;
    }

    return $ResultSets 

    $query = $null;

    $objDataSet = $null;

    $objConnection.Close();
    $objConnection = $null;
}

Get-ChildItem $FolderToSQLFiles -Filter *.sql | Foreach-Object {
    $tmpSQLfilePath = $_.FullName #getting the sql file full path
    $tmpSQLfileContent = (Get-Content $tmpSQLfilePath) -join "`n"  #getting the content of the sql

    GetSQLresults -SQLqueryText $tmpSQLfileContent  #passing the sql query to the executing funciton
}

最佳答案 我会在SELECT子句中添加另一个计算列(Col006_Description)：

SELECT ..., CASE WHEN Col006 IS NULL THEN '(null)' WHEN Col006 = '' THEN '(empty)' ELSE '' END AS Col006_Description, ...
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