MySQL Error 1110: ER_FIELD_SPECIFIED_TWICE – How to Resolve Duplicate Column Specification

August 5, 2025

MySQL throws ER_FIELD_SPECIFIED_TWICE (error 1110) when the same column appears more than once in a SELECT, INSERT, or UPDATE list, violating SQL syntax rules.

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What is MySQL error 1110 (ER_FIELD_SPECIFIED_TWICE)?

MySQL Error 1110: ER_FIELD_SPECIFIED_TWICE occurs when the same column is listed twice in a SELECT, INSERT, or UPDATE clause. Remove or alias the duplicate column name to fix the issue.

Error Highlights

Typical Error Message

Column '%s' specified twice

Error Type

Syntax Error

Language

MySQL

Symbol

ER_FIELD_SPECIFIED_TWICE

Error Code

1110

SQL State

Explanation

Example H2

Example H3

What is MySQL error 1110 (ER_FIELD_SPECIFIED_TWICE)?<\/h2>Error code 1110 with condition name ER_FIELD_SPECIFIED_TWICE signals that MySQL detected a duplicate column name in the query list.<\/p>

The server stops execution because returning or updating the same column twice can create ambiguous results and break deterministic behavior.<\/p>

What Causes This Error?<\/h3>Duplicate columns in a SELECT list generate the error when MySQL cannot decide which value to return.<\/p>

INSERT ...

SELECT and UPDATE statements that name the same column multiple times halt at parse time for the same reason.<\/p>

How to Fix MySQL Error 1110: ER_FIELD_SPECIFIED_TWICE<\/h3>Locate the repeated column name and either remove the extra reference or supply an alias using AS.<\/p>

Verify joins and subqueries that pull overlapping column names, especially when using SELECT * along with explicit columns.<\/p>

Common Scenarios and Solutions<\/h3>Joining two identical tables often returns columns with the same name; prefix the field with table alias or change the output name.<\/p>

INSERT ...

SELECT where the target list already contains that column requires aligning column order or excluding duplicates.<\/p>

Best Practices to Avoid This Error<\/h3>Always enumerate needed columns instead of SELECT * to prevent unintended duplication.<\/p>

Run queries in a linting SQL editor like Galaxy, which highlights duplicate column references before execution.<\/p>

Common Causes

Selecting * With Explicit Columns<\/h3>Using SELECT * and then naming specific columns can include the same field twice, triggering error 1110.<\/p>

Self-Join Without Aliasing<\/h3>A self-join that selects the same column from both sides without aliasing duplicates the column in the result set.<\/p>

Copy-Insert Mismatch<\/h3>An INSERT ...

SELECT statement may list a column twice when the SELECT clause already contains it, causing the server to fail.<\/p>

Update Clause Typos<\/h3>UPDATE statements that mistakenly set the same column more than once violate syntax rules and produce the error.<\/p>.

Related Errors

FAQs

Can I ignore Error 1110 in MySQL?<\/h3>No. The server halts query execution. You must remove or rename the duplicate column.<\/p>

Does adding an alias always fix the problem?<\/h3>Aliasing works when you genuinely need the same column twice, otherwise drop the extra reference.<\/p>

Will SELECT * ever be safe?<\/h3>It is safe only if no other columns are listed. Mixing SELECT * with named columns often introduces duplicates.<\/p>

How does Galaxy help avoid Error 1110?<\/h3>Galaxy’s SQL editor flags duplicate column names in real time and its AI copilot rewrites queries to eliminate the conflict.<\/p>

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