Add Join, LeftJoin, RightJoin and FullJoin

README.md

@@ -161,9 +161,7 @@ fmt.Printf("Most expensive offer: $%.2f\n", minAmount)
 
 #### Joins
 
-There are no helper methods to construct a JOIN clause.
-
-Consider using the "old style" syntax for INNER JOINs:
+There are helper methods to construct a JOIN clause: `Join`, `LeftJoin`, `RightJoin` and `FullJoin`.
 
 ```go
 var (
@@ -177,8 +175,7 @@ err := sqlf.From("offers o").
     Select("price").To(&price).
     Where("is_deleted = false").
     // Join
-    From("products p").
-    Where("p.id = o.product_id").
+    LeftJoin("products p", "p.id = o.product_id").
     // Bind a column from joined table to variable
     Select("p.name").To(&productName).
     // Print top 10 offers
@@ -200,7 +197,7 @@ var (
     name  string
     value string
 )
-err := sqlf.From("t1 FULL JOIN t2 ON t1.num = t2.num AND t2.value IN (?, ?)", "xxx", "yyy").
+err := sqlf.From("t1 CROSS JOIN t2 ON t1.num = t2.num AND t2.value IN (?, ?)", "xxx", "yyy").
     Select("t1.num").To(&num).
     Select("t1.name").To(&name).
     Select("t2.value").To(&value).

bench_test.go

@@ -221,3 +221,18 @@ func BenchmarkWith(b *testing.B) {
 		q.Close()
 	}
 }
+
+func BenchmarkIn(b *testing.B) {
+	a := make([]interface{}, 50)
+	for i := 0; i < len(a); i++ {
+		a[i] = i + 1
+	}
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		q := sqlf.From("orders").
+			Select("id").
+			Where("status").In(a...)
+		s = q.String()
+		q.Close()
+	}
+}

stmt.go

@@ -314,7 +314,10 @@ func (q *Stmt) From(expr string, args ...interface{}) *Stmt {
 /*
 Where adds a filter:
 
-	sqlf.Select("id, name").From("users").Where("email = ?", email).Where("is_active = 1")
+	sqlf.From("users").
+		Select("id, name").
+		Where("email = ?", email).
+		Where("is_active = 1")
 
 */
 func (q *Stmt) Where(expr string, args ...interface{}) *Stmt {
@@ -339,11 +342,45 @@ func (q *Stmt) In(args ...interface{}) *Stmt {
 		}
 	}
 	buf.WriteString(")")
+
 	q.addChunk(posWhere, "", bufToString(&buf.B), args, " ")
+
 	bytebufferpool.Put(buf)
 	return q
 }
 
+/*
+Join adds an INNERT JOIN clause to SELECT statement
+*/
+func (q *Stmt) Join(table, on string) *Stmt {
+	q.join("JOIN ", table, on)
+	return q
+}
+
+/*
+LeftJoin adds a LEFT OUTER JOIN clause to SELECT statement
+*/
+func (q *Stmt) LeftJoin(table, on string) *Stmt {
+	q.join("LEFT JOIN ", table, on)
+	return q
+}
+
+/*
+RightJoin adds a RIGHT OUTER JOIN clause to SELECT statement
+*/
+func (q *Stmt) RightJoin(table, on string) *Stmt {
+	q.join("RIGHT JOIN ", table, on)
+	return q
+}
+
+/*
+FullJoin adds a FULL OUTER JOIN clause to SELECT statement
+*/
+func (q *Stmt) FullJoin(table, on string) *Stmt {
+	q.join("FULL JOIN ", table, on)
+	return q
+}
+
 // OrderBy adds the ORDER BY clause to SELECT statement
 func (q *Stmt) OrderBy(expr ...string) *Stmt {
 	q.addChunk(posOrderBy, "ORDER BY", strings.Join(expr, ", "), nil, ", ")
@@ -555,6 +592,22 @@ func (q *Stmt) Clone() *Stmt {
 	return stmt
 }
 
+// join adds a join clause to a SELECT statement
+func (q *Stmt) join(joinType, table, on string) (index int) {
+	buf := bytebufferpool.Get()
+	buf.WriteString(joinType)
+	buf.WriteString(table)
+	buf.Write(joinOn)
+	buf.WriteString(on)
+	buf.WriteByte(')')
+
+	index = q.addChunk(posFrom, "", bufToString(&buf.B), nil, " ")
+
+	bytebufferpool.Put(buf)
+
+	return index
+}
+
 // addChunk adds a clause or expression to a statement.
 func (q *Stmt) addChunk(pos int, clause, expr string, args []interface{}, sep string) (index int) {
 	// Remember the position
@@ -653,6 +706,7 @@ var (
 	space            = []byte{' '}
 	placeholder      = []byte{'?'}
 	placeholderComma = []byte{'?', ','}
+	joinOn           = []byte{' ', 'O', 'N', ' ', '('}
 )
 
 const (

stmt_test.go

@@ -209,3 +209,27 @@ func TestClone(t *testing.T) {
 	assert.NotEqual(t, q.Args(), q2.Args())
 	assert.NotEqual(t, q.String(), q2.String())
 }
+
+func TestJoin(t *testing.T) {
+	q := sqlf.From("orders o").Select("id").Join("users u", "u.id = o.user_id")
+	defer q.Close()
+	assert.Equal(t, "SELECT id FROM orders o JOIN users u ON (u.id = o.user_id)", q.String())
+}
+
+func TestLeftJoin(t *testing.T) {
+	q := sqlf.From("orders o").Select("id").LeftJoin("users u", "u.id = o.user_id")
+	defer q.Close()
+	assert.Equal(t, "SELECT id FROM orders o LEFT JOIN users u ON (u.id = o.user_id)", q.String())
+}
+
+func TestRightJoin(t *testing.T) {
+	q := sqlf.From("orders o").Select("id").RightJoin("users u", "u.id = o.user_id")
+	defer q.Close()
+	assert.Equal(t, "SELECT id FROM orders o RIGHT JOIN users u ON (u.id = o.user_id)", q.String())
+}
+
+func TestFullJoin(t *testing.T) {
+	q := sqlf.From("orders o").Select("id").FullJoin("users u", "u.id = o.user_id")
+	defer q.Close()
+	assert.Equal(t, "SELECT id FROM orders o FULL JOIN users u ON (u.id = o.user_id)", q.String())
+}