feat: Add HAVING support to MySQL (#1806)

Author: kyleconroy

internal/endtoend/testdata/having/mysql/go/db.go

@@ -0,0 +1,10 @@
+CREATE TABLE weather (
+  city     text    NOT NULL,
+  temp_lo  integer NOT NULL
+);
+
+-- name: ColdCities :many
+SELECT city
+FROM weather
+GROUP BY city
+HAVING max(temp_lo) < ?;

internal/endtoend/testdata/having/mysql/go/models.go

@@ -0,0 +1,12 @@
+{
+	"version": "1",
+	"packages": [
+		{
+			"path": "go",
+			"engine": "mysql",
+			"name": "querytest",
+			"schema": "query.sql",
+			"queries": "query.sql"
+		}
+	]
+}

internal/endtoend/testdata/having/mysql/go/query.sql.go

@@ -0,0 +1,10 @@
+CREATE TABLE weather (
+  city     text    NOT NULL,
+  temp_lo  integer NOT NULL
+);
+
+-- name: ColdCities :many
+SELECT city
+FROM weather
+GROUP BY city
+HAVING max(temp_lo) < $1;

internal/endtoend/testdata/having/mysql/query.sql

@@ -0,0 +1,12 @@
+{
+	"version": "1",
+	"packages": [
+		{
+			"path": "go",
+			"engine": "postgresql",
+			"name": "querytest",
+			"schema": "query.sql",
+			"queries": "query.sql"
+		}
+	]
+}

internal/endtoend/testdata/having/mysql/sqlc.json

@@ -497,6 +497,7 @@ func (c *cc) convertSelectStmt(n *pcast.SelectStmt) *ast.SelectStmt {
 		TargetList:   c.convertFieldList(n.Fields),
 		FromClause:   c.convertTableRefsClause(n.From),
 		GroupClause:  c.convertGroupByClause(n.GroupBy),
+		HavingClause: c.convertHavingClause(n.Having),
 		WhereClause:  c.convert(n.Where),
 		WithClause:   c.convertWithClause(n.With),
 		WindowClause: windowClause,
@@ -904,7 +905,10 @@ func (c *cc) convertGroupByClause(n *pcast.GroupByClause) *ast.List {
 }
 
 func (c *cc) convertHavingClause(n *pcast.HavingClause) ast.Node {
-	return todo(n)
+	if n == nil {
+		return nil
+	}
+	return c.convert(n.Expr)
 }
 
 func (c *cc) convertIndexAdviseStmt(n *pcast.IndexAdviseStmt) ast.Node {