A lightweight, injection-proof query language that parses human-readable filter expressions into a portable AST, transpiles to SQL across ClickHouse, PostgreSQL, and StarRocks, evaluates in-memory, and ships with a Vue 3 editor — with full cross-language parity in Go, Python, and JavaScript.

Common Query Patterns

Full examples with parse → generate → run for each pattern: Query Recipes.

Installation

Go:

go get github.com/iamtelescope/flyql/golang

Python:

pip install flyql
# or
uv add flyql

JavaScript:

npm install flyql

Quick Start

Python:

from flyql import parse
from flyql.generators.clickhouse.generator import to_sql_where
from flyql.generators.clickhouse.column import Column

result = parse("status >= 400 and host like 'prod%'")

columns = {
    "status": Column("status", "UInt32"),
    "host": Column("host", "String"),
}

sql = to_sql_where(result.root, columns)

JavaScript:

import { parse } from 'flyql'
import { generateWhere, newColumn } from 'flyql/generators/clickhouse'

const result = parse("status >= 400 and host like 'prod%'")

const columns = {
    status: newColumn({ name: 'status', type: 'UInt32' }),
    host: newColumn({ name: 'host', type: 'String' }),
}

const sql = generateWhere(result.root, columns)

Go:

import (
	flyql "github.com/iamtelescope/flyql/golang"
	"github.com/iamtelescope/flyql/golang/generators/clickhouse"
)

result, err := flyql.Parse("status >= 400 and host like 'prod%'")

columns := map[string]*clickhouse.Column{
	"status": clickhouse.NewColumn(clickhouse.ColumnDef{Name: "status", Type: "UInt32"}),
	"host":   clickhouse.NewColumn(clickhouse.ColumnDef{Name: "host", Type: "String"}),
}

sql, err := clickhouse.ToSQLWhere(result.Root, columns)

Basic Query Structure

A query consists of one or more conditions connected by boolean operators (and, or, not). Conditions can be comparisons or truthy checks.

status=200 and active and not archived

More examples:

-- comparisons with or
service!=api or user="john doe"

-- regex match and negation
message~"error.*" and not debug

-- grouped conditions
(a=1 or b=2) and not (c=3 and d=4)

-- list membership
status in [200, 201] and method not in ['DELETE', 'PUT']

-- temporal functions
timestamp > ago(1h) and level = 'error'

-- timezone-aware date
date = today('Europe/Berlin')

-- start of week
created_at > startOf('week')

-- Date (calendar day) vs DateTime (instant) column types drive
-- schema-aware matcher coercion: ISO-8601 literals auto-parse and the
-- record value is compared at the declared granularity.
event_day = '2026-04-06'        -- Type.Date column: Y/M/D compare
ts > '2026-04-06T21:00:00Z'     -- Type.DateTime column: ms-granularity compare

For more examples, see the E2E report.

Syntax

Operators

FlyQL supports the following comparison operators:

List Operators

Use in and not in to check if a value is in a list:

status in [200, 201, 204]
env not in ['prod', 'staging']

Rules:

• Values are enclosed in square brackets [] and separated by commas
• Values can be mixed types: [200, 'ok', true, null]
• String values must be quoted: ['a', 'b']
• Number values are unquoted: [1, 2, 3]
• Empty list [] is allowed (in [] is always false, not in [] is always true)

Like Operators

Use like and ilike for SQL-style pattern matching:

-- starts with "error"
message like 'error%'

-- contains "prod"
host like '%prod%'

-- _ matches any single character
path like '/api/_/status'

-- case-insensitive
message ilike '%Error%'

-- negated
host not like 'test%'

Wildcards:

• % matches any sequence of characters (including empty)
• _ matches exactly one character
• \% and \_ match literal % and _

Truthy Checks

A standalone key without an operator checks if the field has a truthy value:

active
message and status

A value is considered falsy if it is:

• null / None / missing
• Empty string ""
• Zero 0
• Boolean false

Everything else is truthy.

Negation Operator

Use not to negate any expression:

-- field is falsy
not active

-- status is not 200
not status=200

-- negates the grouped expression
not (a=1 and b=2)

-- combine with other conditions
active and not archived

Double negation cancels out: not not active is equivalent to active.

Boolean Operators and Parentheses

• Boolean operators - Use and to require all conditions to be true and or to allow for either condition.
• Negation - Use not before any expression to negate it.
• Parentheses - Use ( and ) to group conditions and set the precedence of operations (parentheses must be matched on both sides to avoid errors).

Temporal Functions

FlyQL supports temporal function calls as values for time-relative filters:

-- last 1 hour
timestamp > ago(1h)

-- compound: 1 hour 30 minutes
timestamp > ago(1h30m)

-- before current time
updated_at < now()

-- today's date
date = today()

-- today in timezone
date = today('Europe/Berlin')

-- start of today
created_at > startOf('day')

-- Monday 00:00
created_at > startOf('week')

-- first of month
created_at > startOf('month', 'UTC')

• Duration units: s (seconds), m (minutes), h (hours), d (days), w (weeks)
• Timezones: IANA timezone names (e.g., 'Europe/Berlin', 'Asia/Tokyo')
• Operators: Only comparison operators (=, !=, >, >=, <, <=) work with functions
• Bare names: field=ago (no parens) is a column reference, not a function

Nested Keys

Use dot-separated paths to access nested fields in JSON, Map, or structured data:

request.url = "/api/users"
response.headers.content_type = "application/json"
metadata.labels.env = prod

When a key segment itself contains a dot, wrap it in quotes so the dot is not treated as a separator:

"app.config".debug = true
metadata."dotted.key".value = 123

Nested keys work with all operators:

request.status >= 400 and response.body ~ "error" and not request.internal

Transformers

Transformers modify column values before comparison using the pipe (|) syntax. They can be chained left-to-right:

-- convert to uppercase before comparing
message|upper = "ERROR"

-- chain multiple transformers
message|lower|len > 100

Built-in transformers:

General Query Syntax Rules

• Standalone keys - A key without an operator is treated as a truthy check.
• Comparisons - A key with an operator must have a corresponding value.
• Spaces - Spaces around operators are allowed (status=200 and status = 200 are equivalent).

Handling values

• Without spaces - If the value contains no spaces, you can write it directly (e.g., status=200).
• With spaces - If the value includes spaces, enclose it in single (') or double (") quotes (e.g., user="John Doe" or user='John Doe').
• Escaping quotes - If the value itself contains quotes, these must be properly escaped (e.g. user='John\'s Doe').

Compatibility

SQL Dialects: ClickHouse, PostgreSQL, StarRocks

Formatted SQL Output

Generators accept an opt-in format: true option that breaks WHERE at boolean operators and puts one SELECT column per line. Output is whitespace-only different from the default. See Formatted output.

Editor

FlyQL ships with a Vue 3 editor component that provides syntax highlighting, autocomplete, and schema-driven value suggestions:

import { FlyqlEditor } from 'flyql-vue'
import 'flyql-vue/flyql.css'

<FlyqlEditor v-model="query" :columns="columns" :dark="true" @submit="onSubmit" />

See the editor documentation for the full API reference.

Documentation

Full documentation: docs.flyql.dev

Contributing

See CONTRIBUTING.md for development guidelines and requirements.

Security

See SECURITY.md for reporting vulnerabilities.

License

MIT