I have chosen Azure as the database. Here is an example of the SQL before and after formatting.
DECLARE @start_date DATE='04-01-2021'
DECLARE @end_date DATE='04-30-2021'
DECLARE @supplier INT=10486 --Enter Supplier Number
SELECT
invoice_hdr.invoice_no,
invoice_hdr.bill2_name
FROM oe_line
INNER JOIN invoice_hdr ON oe_line.order_no=invoice_hdr.order_no
WHERE
oe_line.supplier_id=@supplier
AND CAST(invoice_hdr.invoice_date AS DATE)>=@start_date
AND CAST(invoice_hdr.invoice_date AS DATE)<=@end_date
DECLARE @start_date DATE='04-01-2021' DECLARE @end_date DATE='04-30-2021' DECLARE @supplier INT=10486 --Enter Supplier Number
SELECT
invoice_hdr.invoice_no,
invoice_hdr.bill2_name
FROM oe_line
INNER JOIN invoice_hdr ON oe_line.order_no=invoice_hdr.order_no
WHERE
oe_line.supplier_id=@supplier
AND CAST(invoice_hdr.invoice_date AS DATE)>=@start_date
AND CAST(invoice_hdr.invoice_date AS DATE)<=@end_date