Add implicit cross join support

internal/jet/clause.go

@@ -45,19 +45,25 @@ func (s *ClauseSelect) Serialize(statementType StatementType, out *SQLBuilder, o
 
 // ClauseFrom struct
 type ClauseFrom struct {
-	Table Serializer
+	Tables []Serializer
 }
 
 // Serialize serializes clause into SQLBuilder
 func (f *ClauseFrom) Serialize(statementType StatementType, out *SQLBuilder, options ...SerializeOption) {
-	if f.Table == nil {
+	if len(f.Tables) == 0 { // SELECT statement does not have to have FROM clause
 		return
 	}
 	out.NewLine()
 	out.WriteString("FROM")
 
 	out.IncreaseIdent()
-	f.Table.serialize(statementType, out, FallTrough(options)...)
+	for i, table := range f.Tables {
+		if i > 0 {
+			out.WriteString(",")
+			out.NewLine()
+		}
+		table.serialize(statementType, out, FallTrough(options)...)
+	}
 	out.DecreaseIdent()
 }
 

internal/jet/table.go

@@ -136,9 +136,6 @@ func (t *joinTableImpl) TableName() string {
 	return ""
 }
 
-func (t *joinTableImpl) AS(alias string) {
-}
-
 func (t *joinTableImpl) columns() []Column {
 	var ret []Column
 

internal/testutils/test_utils.go

@@ -8,6 +8,7 @@ import (
 	"github.com/go-jet/jet/v2/internal/utils"
 	"github.com/go-jet/jet/v2/qrm"
 	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"io/ioutil"
 	"os"
@@ -116,7 +117,12 @@ func AssertDebugStatementSql(t *testing.T, query jet.Statement, expectedQuery st
 	}
 
 	debuqSql := query.DebugSql()
-	require.Equal(t, debuqSql, expectedQuery)
+	if !assert.Equal(t, debuqSql, expectedQuery) {
+		fmt.Println("Expected: ")
+		fmt.Println(expectedQuery)
+		fmt.Println("Got: ")
+		fmt.Println(debuqSql)
+	}
 }
 
 // AssertSerialize checks if clause serialize produces expected query and args

mysql/select_statement.go

@@ -41,7 +41,7 @@ type SelectStatement interface {
 	Expression
 
 	DISTINCT() SelectStatement
-	FROM(table ReadableTable) SelectStatement
+	FROM(tables ...ReadableTable) SelectStatement
 	WHERE(expression BoolExpression) SelectStatement
 	GROUP_BY(groupByClauses ...jet.GroupByClause) SelectStatement
 	HAVING(boolExpression BoolExpression) SelectStatement
@@ -70,7 +70,9 @@ func newSelectStatement(table ReadableTable, projections []Projection) SelectSta
 		&newSelect.Limit, &newSelect.Offset, &newSelect.For, &newSelect.ShareLock)
 
 	newSelect.Select.ProjectionList = projections
-	newSelect.From.Table = table
+	if table != nil {
+		newSelect.From.Tables = []jet.Serializer{table}
+	}
 	newSelect.Limit.Count = -1
 	newSelect.Offset.Count = -1
 	newSelect.ShareLock.Name = "LOCK IN SHARE MODE"
@@ -103,8 +105,10 @@ func (s *selectStatementImpl) DISTINCT() SelectStatement {
 	return s
 }
 
-func (s *selectStatementImpl) FROM(table ReadableTable) SelectStatement {
+func (s *selectStatementImpl) FROM(tables ...ReadableTable) SelectStatement {
-	s.From.Table = table
+	for _, table := range tables {
+		s.From.Tables = append(s.From.Tables, table)
+	}
 	return s
 }
 

postgres/select_statement.go

@@ -44,7 +44,7 @@ type SelectStatement interface {
 	Expression
 
 	DISTINCT() SelectStatement
-	FROM(table ReadableTable) SelectStatement
+	FROM(tables ...ReadableTable) SelectStatement
 	WHERE(expression BoolExpression) SelectStatement
 	GROUP_BY(groupByClauses ...jet.GroupByClause) SelectStatement
 	HAVING(boolExpression BoolExpression) SelectStatement
@@ -76,7 +76,9 @@ func newSelectStatement(table ReadableTable, projections []Projection) SelectSta
 		&newSelect.Limit, &newSelect.Offset, &newSelect.For)
 
 	newSelect.Select.ProjectionList = projections
-	newSelect.From.Table = table
+	if table != nil {
+		newSelect.From.Tables = []jet.Serializer{table}
+	}
 	newSelect.Limit.Count = -1
 	newSelect.Offset.Count = -1
 
@@ -106,8 +108,10 @@ func (s *selectStatementImpl) DISTINCT() SelectStatement {
 	return s
 }
 
-func (s *selectStatementImpl) FROM(table ReadableTable) SelectStatement {
+func (s *selectStatementImpl) FROM(tables ...ReadableTable) SelectStatement {
-	s.From.Table = table
+	for _, table := range tables {
+		s.From.Tables = append(s.From.Tables, table)
+	}
 	return s
 }
 

postgres/table_test.go

@@ -99,3 +99,26 @@ CROSS JOIN db.table2`)
 CROSS JOIN db.table2
 CROSS JOIN db.table3`)
 }
+
+func TestImplicitCROSS_JOIN(t *testing.T) {
+	assertDebugStatementSql(t,
+		SELECT(table1Col1, table2Col3).
+			FROM(table1, table2),
+		`
+SELECT table1.col1 AS "table1.col1",
+     table2.col3 AS "table2.col3"
+FROM db.table1,
+     db.table2;
+`)
+	assertDebugStatementSql(t,
+		SELECT(
+			table1Col1, table2Col3,
+		).FROM(table1, table2, table3),
+		`
+SELECT table1.col1 AS "table1.col1",
+     table2.col3 AS "table2.col3"
+FROM db.table1,
+     db.table2,
+     db.table3;
+`)
+}