Solving "#134 Duplicate 'Unique Key'" Error

Being a software engineer is quite challenging. You are often in a situation of fixing errors and making sure all the applications work without any glitches. One of the most common issues you might encounter is Error #134 Duplicate 'Unique Key' problem. It is a technical mistake that can waste your time, energy and resources.

This guide will provide you with all the information you need to understand and fix this issue with ease.

What is Error #134 Duplicate 'Unique Key' Problem?

Error #134 Duplicate 'Unique Key' Problem is one of the most common issues you might come across while working as a software engineer. It usually surfaces when you assign the same value to two or more rows in the same table. Every primary and foreign means to connect the tables must have a unique value to match.

What are the Causes of this Problem?

The most common cause of this problem is accidentally assigning the same value to two or more records in a table. This could be due to a lack of a uniqueness constraint placed on the table. In certain cases, in which a change or an update is made in the coding, this can also lead to a similar issue.

How to Troubleshoot and Fix the Error #134 Duplicate 'Unique Key' Problem

Look at All the Records: Start by having a look at all the records that have the same duplicated value. Identify the columns which have this problem and the table to which it belongs.

Check the Integrity of the Data: You need to make sure there are no integrity violations with all the values present in the columns. Also, there should not be any null values in the columns.

Check For Inconsistencies in the Data: Have a look to make sure there are no inconsistencies in the data like having the same value in a single row multiple times.

Create a Unique Constraint: This is the most important step and it usually fixes the issue permanently. Create a unique constraint on the table by altering the existing table.

Make Necessary Changes and Modifications: After creating a unique constraint, you will have to make certain modifications like adding columns for deleted or merged values and also making other necessary changes.


What do I need to check when I encounter Error #134 Duplicate 'Unique Key' Problem?

When you face the error #134 problem, you need to check all the records that have duplicated values, the columns which have this problem, and the integrity of the data. You should also check for inconsistencies in the data and then create a unique constraint.

How can I create the unique constraint?

Creating a unique constraint is the most important step and requires you to alter the existing table. To do this, you need to add 'unique constraint' in the same table utilizing the ALTER TABLE statement.

What type of modifications will I have to make after creating the unique constraint?

Once the unique constraint is created, you will have to make certain modifications like adding columns for deleted or merged values and making other necessary changes.

What should I do if the error still persists?

If the error still persists after creating the unique constraint, you may have to delete the rows with the same value exist in the same table. Once they are deleted, you may have to recreate the unique constraint to avoid this issue from occurring again.

Can I use unique index instead of unique constraint?

Yes, you can use a unique index instead of a unique constraint. It is an advanced type of constraint that allows you to enforce the uniqueness of multiple columns.

What Is Error #134 Duplicate 'Unique Key' Problem?

How to Fix Error #134 Duplicate 'Unique Key' Problem?

Using Unique Index Instead of Unique Constraint

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