To understand the process, I will do a simple one line estimate example.

FIRST TO CREATE THE ESTIMATE
The following SQL statement will create a new estimate:

INSERT INTO "EstimateLine" ("CustomerRefListID", "RefNumber", "EstimateLineItemRefListID",
"EstimateLineDesc", "EstimateLineRate", "EstimateLineAmount", "EstimateLineSalesTaxCodeRefListID",
"FQSaveToCache") VALUES ('470001-1071525403', '201', '250000-933272656',
'Building permit No 201', 100.00000, 100.00, '20000-999022286', 0)

which results in the following estimate in the QuickBooks 2006 Premier USA Edition - Sample Rock Castle Construction company file:

NEXT, TO CREATE  A SALES ORDER FROM A ESTIMATE
When we're ready to create the Sales Order we can read the EstimateLine table and insert it into the SalesOrderLine table like this:

INSERT INTO "SalesOrderLine" ("CustomerRefListID", "RefNumber", "Memo", "SalesOrderLineItemRefListID",
"SalesOrderLineDesc", "SalesOrderLineRate", "SalesOrderLineAmount", "SalesOrderLineSalesTaxCodeRefListID",
"FQSaveToCache")
Select "CustomerRefListID", "RefNumber", {fn CONCAT('Estimate ', "RefNumber")} as "Memo","EstimateLineItemRefListID",
"EstimateLineDesc", "EstimateLineRate", "EstimateLineAmount", "EstimateLineSalesTaxCodeRefListID",
"FQSaveToCache" from EstimateLine where "RefNumber"='201' and "EstimateLineSeqNo"=1

Note: This is one complete SQL statement, for multiple estimate lines you would set FQSaveToCache to 1 instead (using: 1 as "FQSaveToCache") and loop the EstimateLineSeqNos until the last one setting FQSaveToCache to 0.

The Estimate now appears as a Sales Order in QuickBooks with "Estimate 201" in the memo field the same way QuickBooks creates a Sales Order from a Estimate.

See: How do I create Estimates? for more on multiple lines.