Identifier Types

Part of Entiqon / Database / Token / Types

The identifier package classifies SQL expressions into broad syntactic categories. This classification is purely syntactic, not semantic, and is used internally by token resolvers and helpers.

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Purpose

• Provide a dependency-free enum (identifier.Type) to represent the form of a SQL expression.
• Enable higher-level tokens (Field, Table, …) and builders (SelectBuilder, …) to share consistent semantics without cycles.
• Support helpers such as ClassifyExpression to normalize input into one of the defined categories.

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Categories

The following categories are supported:

Constant	Description	Example
Invalid	Could not classify	""
Subquery	Parenthesized SELECT	(SELECT * FROM users)
Computed	Other parenthesized expression	(a + b)
Aggregate	Aggregate function	SUM(qty), COUNT(*)
Function	Any other function or call	JSON_EXTRACT(data, '$.id')
Literal	Quoted string or numeric constant	'abc', "xyz", 42
Identifier	Plain table or column name (default fallback)	users, id

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Example

package main

import (
    "fmt"

    "github.com/entiqon/db/token/types/identifier"
)

func main() {
    var t identifier.Type

    // Functions render as capitalized names
    t = identifier.Function
    fmt.Println(t)

    // Subqueries render as capitalized names
    t = identifier.Subquery
    fmt.Println(t)

    // Invalid or unknown types are handled safely
    fmt.Println(identifier.Invalid)
    fmt.Println(identifier.Type(99))

    // Output:
    // Function
    // Subquery
    // Invalid
    // Unknown
}

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License

Released under the MIT License.
Copyright © 2025 Entiqon Contributors