Query Gravity Forms entries of specific form and some extra meta values.

lookup-gf-entries-meta.sql

SELECT
	entry.id AS entry_id,
	entry.date_created AS entry_created_on,
	entry.form_id AS form_id,
	form.title AS form_title,
	user.display_name AS user_display_name,
	emtry_meta_km.meta_value AS number_kilometers,
	emtry_meta_office_id.meta_value AS office_id,
	emtry_meta_date.meta_value AS period,
	office.code AS office_code,
	office.name AS office_name
FROM
	wp_gf_entry AS entry
		LEFT JOIN
	wp_gf_form AS form
			ON entry.form_id = form.id
		LEFT JOIN
	wp_users AS user
			ON entry.created_by = user.ID
		LEFT JOIN
	wp_gf_entry_meta AS emtry_meta_km
			ON (
				emtry_meta_km.entry_id = entry.id
					AND
				emtry_meta_km.meta_key = '1'
			)
		LEFT JOIN
	wp_gf_entry_meta AS emtry_meta_office_id
			ON (
				emtry_meta_office_id.entry_id = entry.id
					AND
				emtry_meta_office_id.meta_key = 'lookup_office_id'
			)
		LEFT JOIN
	wp_gf_entry_meta AS emtry_meta_date
			ON (
				emtry_meta_date.entry_id = entry.id
					AND
				emtry_meta_date.meta_key = 'lookup_year'
			)
		LEFT JOIN
	wp_lookup_offices AS office
			ON emtry_meta_office_id.meta_value = office.id
WHERE
	entry.form_id = 6
;