From a7c1eebcbc96c8ecef15a30978091aae71f229c9 Mon Sep 17 00:00:00 2001
From: Bar Weiss <bar.weiss@datadoghq.com>
Date: Thu, 20 Mar 2025 10:32:09 +0200
Subject: [PATCH 1/2] Fix the order of LIMIT and OFFSET clauses when using the
 Presto flavor (issue #195)

Queries that have both a limit and an offset build a query with a limit clause *before* the offset clause.

```go
fmt.Println(Select("*").From("table").Offset(5).Limit(10))
// SELECT * FROM table LIMIT 10 OFFSET 5
```

This seems to generate syntax errors in Trino. [Presto documentation specifies OFFSET before LIMIT](https://prestodb.io/docs/current/sql/select.html#limit-clause) in the SELECT statement documentation too, but is not very explicit about the reverse not being supported.

If the OFFSET and LIMIT clauses are swapped, the query succeeds.

Expected:

```go
fmt.Println(Select("*").From("table").Offset(5).Limit(10))
// SELECT * FROM table OFFSET 5 LIMIT 10
```
---
 select.go      | 12 +++++++++++-
 select_test.go |  4 ++--
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/select.go b/select.go
index 8b698e0..dde2ece 100644
--- a/select.go
+++ b/select.go
@@ -457,7 +457,7 @@ func (sb *SelectBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{
 			buf.WriteLeadingString("LIMIT ")
 			buf.WriteString(sb.limitVar)
 		}
-	case PostgreSQL, Presto:
+	case PostgreSQL:
 		if len(sb.limitVar) > 0 {
 			buf.WriteLeadingString("LIMIT ")
 			buf.WriteString(sb.limitVar)
@@ -467,6 +467,16 @@ func (sb *SelectBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{
 			buf.WriteLeadingString("OFFSET ")
 			buf.WriteString(sb.offsetVar)
 		}
+	case Presto:
+		if len(sb.offsetVar) > 0 {
+			buf.WriteLeadingString("OFFSET ")
+			buf.WriteString(sb.offsetVar)
+		}
+
+		if len(sb.limitVar) > 0 {
+			buf.WriteLeadingString("LIMIT ")
+			buf.WriteString(sb.limitVar)
+		}
 
 	case SQLServer:
 		// If ORDER BY is not set, sort column #1 by default.
diff --git a/select_test.go b/select_test.go
index 1d631d2..cdebad1 100644
--- a/select_test.go
+++ b/select_test.go
@@ -229,9 +229,9 @@ func ExampleSelectBuilder_limit_offset() {
 	// Presto
 	// #1: SELECT * FROM user
 	// #2: SELECT * FROM user OFFSET ?
-	// #3: SELECT * FROM user LIMIT ? OFFSET ?
+	// #3: SELECT * FROM user OFFSET ? LIMIT ?
 	// #4: SELECT * FROM user LIMIT ?
-	// #5: SELECT * FROM user ORDER BY id LIMIT ? OFFSET ?
+	// #5: SELECT * FROM user ORDER BY id OFFSET ? LIMIT ?
 	//
 	// Oracle
 	// #1: SELECT * FROM user

From baa39209c6b3edc9581cfb322015a45435a20eb8 Mon Sep 17 00:00:00 2001
From: Bar Weiss <bar.weiss@datadoghq.com>
Date: Thu, 20 Mar 2025 10:47:05 +0200
Subject: [PATCH 2/2] Add some in-code documentation

---
 select.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/select.go b/select.go
index dde2ece..6dcbc2e 100644
--- a/select.go
+++ b/select.go
@@ -468,6 +468,10 @@ func (sb *SelectBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{
 			buf.WriteString(sb.offsetVar)
 		}
 	case Presto:
+		// There might be a hidden constraint in Presto requiring offset to be set before limit.
+		// The select statement documentation (https://prestodb.io/docs/current/sql/select.html)
+		// puts offset before limit, and Trino, which is based on Presto, seems
+		// to require this specific order.
 		if len(sb.offsetVar) > 0 {
 			buf.WriteLeadingString("OFFSET ")
 			buf.WriteString(sb.offsetVar)