layout: global title: OPEN statement displayTitle: OPEN statement license: | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Opens a cursor and executes its query, positioning it before the first row.

The OPEN statement executes the query defined in the cursor declaration, binding any parameter markers if specified. Once opened, the cursor can be used with FETCH to retrieve rows.

Syntax

OPEN cursor_name [ USING { constant_expr [ AS param_name ] } [, ...] ]

Parameters

  • cursor_name

    The name of a declared cursor. The cursor can be optionally qualified with a compound statement label to reference a cursor from an outer scope (e.g., outer_label.my_cursor).

  • USING { constant_expr [ AS param_name ] } [, ...]

    Optional clause to bind values to parameter markers in the cursor's query.

    • constant_expr

      A constant expression (literal or variable) to bind to a parameter marker. The expression must be castable to the type expected by the query.

    • AS param_name

      An optional alias for the parameter. For named parameter markers (:param_name), this specifies which parameter to bind. If not specified for positional markers (?), parameters are bound by position.

Examples

-- Open a simple cursor without parameters
> BEGIN
    DECLARE total INT;
    DECLARE my_cursor CURSOR FOR SELECT sum(id) FROM range(10);

    OPEN my_cursor;
    FETCH my_cursor INTO total;
    VALUES (total);
    CLOSE my_cursor;
  END;
45

-- Open cursor with positional parameters
> BEGIN
    DECLARE total INT;
    DECLARE param_cursor CURSOR FOR
      SELECT sum(id) FROM range(100) WHERE id BETWEEN ? AND ?;

    OPEN param_cursor USING 10, 20;
    FETCH param_cursor INTO total;
    VALUES (total);
    CLOSE param_cursor;
  END;
165

-- Open cursor with named parameters
> BEGIN
    DECLARE min_val INT;
    DECLARE named_cursor CURSOR FOR
      SELECT min(id) FROM range(100) WHERE id >= :threshold;

    OPEN named_cursor USING 25 AS threshold;
    FETCH named_cursor INTO min_val;
    VALUES (min_val);
    CLOSE named_cursor;
  END;
25

-- Open cursor using variables as parameters
> BEGIN
    DECLARE lower INT DEFAULT 5;
    DECLARE upper INT DEFAULT 15;
    DECLARE result INT;
    DECLARE var_cursor CURSOR FOR
      SELECT count(*) FROM range(100) WHERE id BETWEEN ? AND ?;

    OPEN var_cursor USING lower, upper;
    FETCH var_cursor INTO result;
    VALUES (result);
    CLOSE var_cursor;
  END;
11

-- Open cursor with various data types
> BEGIN
    DECLARE type_name STRING;
    DECLARE value_sum INT;
    DECLARE type_cursor CURSOR FOR
      SELECT typeof(:p) as type, sum(:p + id) FROM range(3);

    OPEN type_cursor USING 10 AS p;
    FETCH type_cursor INTO type_name, value_sum;
    VALUES (type_name, value_sum);
    CLOSE type_cursor;
  END;
INT|33

-- Qualified cursor name with label
> BEGIN
    outer_lbl: BEGIN
      DECLARE outer_cur CURSOR FOR SELECT max(id) FROM range(10);
      DECLARE max_val INT;

      OPEN outer_cur;

      inner_lbl: BEGIN
        DECLARE inner_cur CURSOR FOR SELECT min(id) FROM range(5);
        DECLARE min_val INT;

        OPEN inner_cur;
        FETCH outer_lbl.outer_cur INTO max_val;
        FETCH inner_cur INTO min_val;
        VALUES (max_val, min_val);
        CLOSE inner_cur;
      END;

      CLOSE outer_cur;
    END;
  END;
9|0

Notes

  • A cursor can only be opened once. Attempting to open an already-opened cursor raises a CURSOR_ALREADY_OPEN error.
  • Parameter binding behavior matches EXECUTE IMMEDIATE:
    • For positional parameters (?), expressions are bound in the order specified.
    • For named parameters (:name), the AS param_name clause specifies the binding.
    • All parameter markers in the query must be bound.
  • Variable references in the cursor's query are evaluated at OPEN time, using current variable values.
  • The cursor's result set is materialized at OPEN time. Subsequent changes to variables or tables do not affect the result set.
  • If the cursor's query raises an error during execution, the cursor remains in a closed state.

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