How to Fix SQL Server Error Code 1060?

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If you’ve encountered SQL Server Error Code 1060, you’re likely seeing a message similar to: “Duplicate column name.” This error can be puzzling, especially when you’re working with large datasets or dynamically generated queries. But don’t worry — this article will walk you through what causes this issue, how to fix it, and how to prevent it in the future.

What Is SQL Server Error Code 1060?

SQL Server Error Code 1060 typically occurs when there’s a duplicate column name specified in a query. This usually happens in a SELECT clause, but it can also occur during CREATE TABLE or ALTER TABLE statements.

Here’s the standard error message associated with it:

“Error 1060: Duplicate column name ‘column_name'”

This means that the query or table schema you’re trying to execute or define includes the same column name more than once, which SQL Server doesn’t allow.

Common Scenarios That Cause This Error

Understanding the root cause is crucial. Let’s explore common scenarios that might trigger Error 1060:

  • Joining tables that have columns with the same name without aliasing them.
  • Importing data into a table where column names clash with existing ones.
  • Dynamic SQL queries generating duplicated column headers.

Steps to Fix SQL Server Error 1060

The solution varies depending on the context of the error. Below are step-by-step instructions for fixing it in different scenarios.

1. Use Column Aliases

If you’re using a JOIN operation, the simplest solution is to use aliases for columns with identical names.

SELECT 
   a.ID, 
   a.Name AS EmployeeName, 
   b.Name AS DepartmentName
FROM Employees a
JOIN Departments b ON a.DeptID = b.ID;

This way, you avoid having two columns named Name in your final result set.

2. Check for Duplicates in Table Definitions

If you’re creating a table and encounter this error, review your DDL statement and remove or rename the duplicate columns:

CREATE TABLE Employees (
   ID INT,
   Name VARCHAR(50),
   Name VARCHAR(100) -- This will cause Error 1060
);

To fix it, eliminate the duplicate or give it a different name:

CREATE TABLE Employees (
   ID INT,
   FirstName VARCHAR(50),
   LastName VARCHAR(100)
);

3. Validate Dynamic SQL Strings

When building queries dynamically, debug your SQL strings before execution. Applications generating SQL dynamically are more prone to logical mistakes, including inserting duplicate columns by accident.

You can do this by outputting the final SQL string and analyzing it:

PRINT @sqlQuery
-- or
SELECT @sqlQuery

This lets you verify whether a column name is repeated in the query.

Troubleshooting Tips

If the above steps don’t resolve your issue, try the following:

  • Run the problematic query in SQL Server Management Studio and check the result set or error line.
  • Use the SQL Server Profiler to trace the query if it’s being run by an application.
  • Check stored procedures or views that may be generating overlapping columns through nested queries.

Preventing Error 1060 in the Future

To avoid encountering Error 1060 again:

  • Always use column aliases for disambiguation, especially when joining multiple tables.
  • Standardize naming conventions across different tables and modules in your database.
  • Avoid SELECT * in queries where tables have overlapping column names.

Conclusion

SQL Server Error Code 1060 is a classic case of a simple mistake with potentially confusing consequences. Whether you’re coding stored procedures or building dynamic SQL, keeping your column names unique and well-aliased can save you a lot of time and debugging effort.

Next time you come across the dreaded “duplicate column name” error, you’ll not only know exactly what causes it but also how to fix and prevent it efficiently. A little diligence now will save you hours of troubleshooting down the line.