How to Resolve Ambiguous Column 'id' Errors in SQL Queries?

Ambiguous column "id" in SQL query

When querying multiple tables containing the same column name (e.g. "id"), the table source of the column must be specified to avoid ambiguity. By default, SQL cannot determine which "id" column to retrieve.

There are two ways to solve this problem:

1. Table name prefix method:

   • Prefix column names with the full table name to clearly identify their source.

   <code class="language-sql">SELECT tbl_names.id, tbl_section.id, name, section
   FROM tbl_names, tbl_section
   WHERE tbl_names.id = tbl_section.id</code>

2. table alias:

   • Assign an alias to each table and prefix the column names with the alias.

   <code class="language-sql">SELECT n.id, s.id, n.name, s.section
   FROM tbl_names n
   JOIN tbl_section s ON s.id = n.id</code>

Table aliasing is the preferred method because it simplifies the query syntax and ensures clarity and conciseness. Table aliasing is also required for certain operations, such as outer joins that do not support traditional ANSI-89 syntax.

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