How to Extract Column Names from an Oracle Table?

Extracting Column Names in Oracle: A Comprehensive Guide

MySQL's information_schema.COLUMNS table isn't directly mirrored in Oracle. This article details how to retrieve column names from an Oracle 11g table, addressing schema and tablespace distinctions, and highlighting security best practices.

Oracle Query Solution

Oracle utilizes the USER_TAB_COLS (or ALL_TAB_COLS for cross-schema access) table to store column metadata. To fetch column names from the 'users' table, owned by 'my_schema', excluding specified columns, use this query:

<code class="language-sql">SELECT column_name
FROM ALL_TAB_COLS
WHERE table_name = 'USERS'
AND owner = 'my_schema'
AND column_name NOT IN ('PASSWORD', 'VERSION', 'ID')</code>

Clarifying Tablespaces and Schemas

It's crucial to understand that in Oracle, tablespaces and schemas are distinct concepts. Tablespaces are storage locations, while schemas represent ownership and organizational structures for database objects. The tablespace is irrelevant when querying column names; only the schema (owner) matters.

Hibernate Criteria API (No Direct HQL Equivalent)

While a direct HQL equivalent doesn't exist, the Hibernate Criteria API offers a comparable approach:

<code class="language-java">Criteria criteria = session.createCriteria(User.class);
criteria.setProjection(Projections.property("columnName"));
criteria.add(Restrictions.eq("tableName", "users"));
criteria.add(Restrictions.in("columnName", new String[] {"name", "email"})); // Excludes columns</code>

Preventing SQL Injection Vulnerabilities

Directly embedding values into SQL queries is highly risky. Always use prepared statements or parameterized queries to prevent SQL injection attacks and safeguard your database. This is crucial for any dynamic queries where table or column names are user-supplied.

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