How to fix Error 479 on Windows Server 2025 / Windows 11

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Why This Error Happens

Error 479 occurs when a TABLESAMPLE clause in a T-SQL query receives an invalid numeric argument for either the ROWS count or the REPEATABLE seed value. SQL Server 2025 strictly validates that these parameters must be positive, non-zero numeric values, so passing a zero, negative number, NULL, or a value derived from a bad variable/expression triggers this exception. This is typically a query-authoring issue rather than a server configuration problem, often introduced by dynamic SQL, ORM-generated queries, or a miscalculated variable being passed into the sampling clause.

Step-by-Step Resolution Guide

Step 1: Locate the Offending Query

  • Check the SQL Server Error Log or Extended Events session for the exact statement text associated with Error 479.
  • Use SELECT * FROM sys.dm_exec_query_stats cross-applied with sys.dm_exec_sql_text to identify recently executed queries containing TABLESAMPLE.
  • Confirm the table name referenced in the error message (%.*ls) to narrow down which object is affected.

Step 2: Inspect and Correct the TABLESAMPLE Syntax

  • Verify the ROWS value is a positive integer greater than 0, e.g., TABLESAMPLE (1000 ROWS) instead of TABLESAMPLE (0 ROWS).
  • If using REPEATABLE, ensure the seed value is a positive bigint, e.g., TABLESAMPLE (10 PERCENT) REPEATABLE (42).
  • Remove any negative signs, NULL substitutions, or unvalidated user input being concatenated into dynamic SQL that builds the clause.

Step 3: Validate Variable Inputs in Dynamic or Parameterized Queries

  • If the ROWS/REPEATABLE value comes from a variable, add a guard clause before execution:
  IF @SampleSize <= 0 SET @SampleSize = 1000;
  • For application-generated queries (ORMs like Entity Framework or Hibernate), check the application layer/config file (commonly under C:\inetpub\wwwroot\App_Data\ or the app’s appsettings.json) for hardcoded sampling parameters that may be defaulting to 0 or negative.

Step 4: Update SQL Server 2025 Cumulative Updates

  • Navigate to Microsoft SQL Server Management Studio > Help > About to confirm your build number.
  • Apply the latest Cumulative Update (CU) via the Microsoft Update Catalog, as early SQL Server 2025 builds had edge-case bugs in seed validation logic for TABLESAMPLE.
  • Restart the SQL Server service via services.msc or Restart-Service MSSQLSERVER in PowerShell after patching.

Alternative or Verification Steps

  • Re-run the corrected query in SQL Server Management Studio (SSMS) and confirm it returns sampled rows without throwing Error 479.
  • If the issue persists despite valid values, run DBCC CHECKTABLE ('YourTableName') to rule out underlying metadata corruption on the target table.