SHOW COLUMNS

Enterprise command reference.

Command Snapshot

Field	Value
Category	DDL and Administration
Mutates Data	No
Scope	Statement
Privilege Model	Requires DDL/administrative privilege according to target object scope.

Purpose

Executes the SHOW COLUMNS SQL command with MonkDB distributed runtime semantics.

Syntax

SHOW COLUMNS { FROM | IN } table_name [ { FROM | IN } table_schema ] [ LIKE 'pattern' | WHERE expression ]

Operational Notes

• Use schema-qualified identifiers in automation and automation pipelines.
• Validate behavior in staging for cluster-impacting or governance-impacting changes.
• Confirm runtime effects through system tables and metrics before and after execution.

When to Use

• Use during planned schema and runtime administration changes.
• Use in automation pipelines with environment-specific validation and rollback strategy.

When Not to Use

• Avoid during incident windows unless the command is part of approved mitigation.
• Avoid schema changes in peak traffic windows without staged rollout.

Common Errors and Troubleshooting

Symptom	Likely Cause	Action
Permission denied / unauthorized	Missing privilege on object or cluster scope	Re-run with required grants or elevated admin role.
Analysis/parse error	Syntax variant or object shape mismatch	Compare with canonical syntax and object definition.
Runtime failure under load	Resource limits, breaker pressure, or node state transitions	Check sys.jobs, sys.operations, sys.checks, and retry after mitigation.

Cross-References

• SQL Command Catalog
• SQL Commands Index
• SQL Reference Overview

Detailed Reference

The SHOW COLUMNS command is commonly used across SQL-based databases, including MonkDB, MySQL, and others, to retrieve metadata about the columns of a specified table. Below is a detailed breakdown of its usage, syntax, parameters, and clauses.

SQL Statement

SHOW COLUMNS { FROM | IN } table_name [ { FROM | IN } table_schema ] [ LIKE 'pattern' | WHERE expression ]

Description

The SHOW COLUMNS command fetches metadata about the columns of a specified table. It provides information such as:

• Column names
• Data types
• Nullability
• Keys (e.g., primary or foreign keys)
• Default values
• Additional attributes (e.g., auto-increment)

Columns are typically displayed in alphabetical order. If more detailed information is required, querying the information_schema.columns table is recommended.

Parameters

• table_name: Specifies the name of the table whose column information is to be retrieved.
• table_schema: Specifies the schema containing the table. If omitted, the default schema (e.g., doc) is used.

Clauses

LIKE Clause

The LIKE clause filters column names based on a string pattern. For example

SHOW COLUMNS FROM table_name LIKE 'prefix%';

This retrieves columns whose names start with prefix..

WHERE Clause

The WHERE clause allows filtering based on more complex conditions. For example

SHOW COLUMNS FROM table_name WHERE data_type = 'VARCHAR';

This retrieves only columns with a VARCHAR data type.

Examples

Basic Usage

Retrieve all columns from a table

SHOW COLUMNS FROM customers;

Specifying Schema

Retrieve columns from a specific schema

SHOW COLUMNS FROM customers IN monkdb;

Using LIKE Clause and filter columns by name pattern

SHOW COLUMNS FROM orders LIKE 'order_%';

Using WHERE Clause and filter columns based on conditions

SHOW COLUMNS FROM payments WHERE data_type = 'DECIMAL';

Example Output

+-------------+----------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------------+----------+------+-----+---------+----------------+ | ID | int(11) | NO | PRI | NULL | auto_increment | | Name | char(35) | NO | | | | | Population | int(11) | NO | | 0 | | +-------------+----------+------+-----+---------+----------------+