Changing selectExprNeedsAlias to consider string literal quotes

sql/plan/str_expr.go

@@ -2,6 +2,7 @@ package plan
 
 import (
 	"github.com/dolthub/go-mysql-server/sql"
+	"github.com/dolthub/go-mysql-server/sql/expression"
 	"github.com/dolthub/go-mysql-server/sql/transform"
 )
 
@@ -20,6 +21,14 @@ func AliasSubqueryString(e sql.Expression) string {
 	if err != nil {
 		panic(err)
 	}
+
+	// String literal values are quoted when their String() method is called, so to avoid that, we
+	// check if we're dealing with a string literal and use it's raw value if so.
+	if literal, ok := e.(*expression.Literal); ok {
+		if s, ok := literal.Value().(string); ok {
+			return s
+		}
+	}
 	return e.String()
 }
 

sql/planbuilder/project.go

@@ -242,6 +242,18 @@ func selectExprNeedsAlias(e *ast.AliasedExpr, expr sql.Expression) bool {
 			return true
 		}
 	})
+	if complex {
+		return true
+	}
+
+	// If the expression's string representation is quoted, trim the quotes before comparing it to the input expression.
+	// InputExpression is assigned in the Vitess layer, and it always trims quotes at that time, too.
+	exprString := expr.String()
+	if strings.HasPrefix(exprString, "'") && strings.HasSuffix(exprString, "'") {
+		exprString = exprString[1 : len(exprString)-1]
+	}
 
-	return complex || e.InputExpression != expr.String()
+	// If the expression's input value does not match expr.String(), then we know that it is not
+	// referenceable and will need an alias.
+	return e.InputExpression != exprString
 }

sql/types/typecheck_test.go

@@ -17,8 +17,9 @@ package types
 import (
 	"testing"
 
-	"github.com/dolthub/go-mysql-server/sql"
 	"github.com/stretchr/testify/assert"
+
+	"github.com/dolthub/go-mysql-server/sql"
 )
 
 func TestIsGeometry(t *testing.T) {