Parse charset introducer for string literals for expressions

enginetest/enginetests.go

@@ -2608,6 +2608,32 @@ func TestCreateTable(t *testing.T, harness Harness) {
 
 		require.Equal(t, s, testTable.Schema())
 	})
+
+	t.Run("create table statement with charset introducer in column definition", func(t *testing.T) {
+		ctx := NewContext(harness)
+		ctx.SetCurrentDatabase("mydb")
+
+		TestQueryWithContext(t, ctx, e, `CREATE TABLE types_with_defaults (
+  pk int NOT NULL,
+  col1 blob DEFAULT (_utf8mb4'abc'),
+  col2 json DEFAULT (json_object(_utf8mb4'a',1)),
+  col3 text DEFAULT (_utf8mb4'abc'),
+  PRIMARY KEY (pk)
+)`, []sql.Row(nil), nil, nil)
+
+		db, err := e.Analyzer.Catalog.Database(ctx, "mydb")
+		require.NoError(t, err)
+
+		_, ok, err := db.GetTableInsensitive(ctx, "types_with_defaults")
+		require.NoError(t, err)
+		require.True(t, ok)
+
+		RunQuery(t, e, harness, "INSERT INTO types_with_defaults (pk) VALUES (1)")
+		TestQueryWithContext(t, ctx, e, "SELECT * FROM types_with_defaults", []sql.Row{{1, "abc", sql.MustJSON(`{"a":1}`), "abc"}}, nil, nil)
+
+		_, _, err = e.Query(ctx, "CREATE TABLE unsupported_charset (pk int NOT NULL, col1 blob DEFAULT (_latin1'abc'))")
+		require.Error(t, err)
+	})
 }
 
 func TestDropTable(t *testing.T, harness Harness) {

sql/parse/parse.go

@@ -3386,7 +3386,20 @@ func unaryExprToExpression(ctx *sql.Context, e *sqlparser.UnaryExpr) (sql.Expres
 			return expression.NewLiteral(exprLiteral.Value(), sql.LongBlob), nil
 		}
 		return expr, nil
+	case "_utf8mb4 ", "_utf8mb3 ", "_utf8 ":
+		expr, err := ExprToExpression(ctx, e.Expr)
+		if err != nil {
+			return nil, err
+		}
+		// must be string type
+		if !sql.IsText(expr.Type()) {
+			return nil, sql.ErrInvalidType.New(expr.Type().String() + " after character set introducer")
+		}
+		return expr, nil
 	default:
+		if strings.HasPrefix(strings.ToLower(e.Operator), "_") {
+			return nil, sql.ErrUnsupportedFeature.New("unsupported character set: " + e.Operator)
+		}
 		return nil, sql.ErrUnsupportedFeature.New("unary operator: " + e.Operator)
 	}
 }