dialects/dialect.go

@@ -335,8 +335,14 @@ func ColumnString(dialect Dialect, col *schemas.Column, includePrimaryKey bool)
 		if _, err := bd.WriteString(" DEFAULT "); err != nil {
 			return "", err
 		}
-		if _, err := bd.WriteString(col.Default); err != nil {
-			return "", err
+		if col.Default == "" {
+			if _, err := bd.WriteString("''"); err != nil {
+				return "", err
+			}
+		} else {
+			if _, err := bd.WriteString(col.Default); err != nil {
+				return "", err
+			}
 		}
 	}
 

integrations/session_schema_test.go

@@ -526,8 +526,9 @@ func TestModifyColum(t *testing.T) {
 		SQLType: schemas.SQLType{
 			Name: "VARCHAR",
 		},
-		Length:   16,
-		Nullable: false,
+		Length:         16,
+		Nullable:       false,
+		DefaultIsEmpty: true,
 	})
 	_, err := testEngine.Exec(alterSQL)
 	assert.NoError(t, err)